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J? H PHYSICAL SCI. LIB. 
 
 Ly^ ^^ff j WATER POLLUTION CONTROL RESEARCH SERIES # 1 3030ELY 5-7 
 
 ^V/A^flBI'^ REC-R2-72- 
 
 DWR NO. 174 
 
 ^')1 
 
 BIO-ENGINEERING ASPECTS OF AGRI CULTU RAL DRAINAGE 
 SAN JOAQUIN VALLEY, CALIFORNIA 
 
 .V1AY14REC'U 
 NOV 1 3 1974 
 OEC 1 3 m4 
 
 _ 1975 
 gl^RECT) 
 
 rPOSSlBlLITY OF REDUCING NITROGEN 
 
 •OCT 4 ^^ 
 
 DRAINAGE WATER BY ON FARM PRACT 
 
 Jan 5 1 37 7 
 
 IN 
 CES 
 
 JUNE 1972 
 
 NVIRONMENTAL PROTECTION AGENCY»RESEARCH AND MONITORIN 
 
 UNITED STATES BUREAU OF R ECL A M ATI O N 
 
BIO-ENGINEERING ASPECTS OF AGRICULTURAL DRAINftGE 
 SAN JOAQUIN VALLEY, CALIFORNIA 
 
 The Bio-Engineering Aspects of Agricultural Drainage reports describe 
 the results of a unique interagency study of the occurrence of nitro- 
 gen and nitrogen removal treatment of subsurface agricultural waste- 
 waters of the San Joaquin Valley, California. 
 
 The three principal agencies involved in the study are the Water 
 Quality Office of the Environmental Protection Agency, the United 
 States Bureau of Reclamation, and the California Department of 
 Water Resources. 
 
 Inquiries pertaining to the Bio-Engineering Aspects of Agricultural 
 Drainage reports should be directed to the author agency, but may 
 be directed to any one of the three principal agencies. 
 
 THE REPORTS 
 
 It is planned that a series of twelve reports will be issued describ- 
 ing the results of the interagency study. 
 
 There will be a sununary report covering all phases of the study. 
 
 A group of four reports will be prepared on the phase of the study 
 related to predictions of subsurface agricultural wastewater quality-- 
 one report by each of the three agencies, and a summary of the three 
 reports. 
 
 Another group of four reports will be prepared on the treatment 
 methods studies and on the biostimulatory testing of the treatment 
 plant effluent. There will be three basic reports and a summary 
 of the three reports. ^This report, "POSSIBILITY OF REDUCING NITROGEN 
 IN DRAINAGE WATER BY ON FARM PRACTICES," is one of the three basic 
 reports of this group. 
 
 The other fchre* planned xep^^s will, covei;>;. (p.) technique;^ to reduce 
 nitrogen dufing tranisport "ot Sto'rag^, (2) removal of nitVate by an 
 algal system, and (3) desalinatibn df subsurface agricultural waste- 
 waters. 
 
BIO-ENGINEERING ASPECTS OF AGRICULTURAL DRAINAGE 
 SAN JOAQUIN VALLEY, CALIFORNIA 
 
 POSSIBILITY OF REDUCING 
 
 NITROGEN IN DRAINAGE WATER BY 
 
 ON FARM PRACTICES 
 
 Prepared by the 
 
 United States Bureau of Reclamation 
 Robert J. Pafford, Jr., Director 
 Region 2 
 
 The agricultural drainage study was conducted under the direction 
 of: 
 
 Robert J. Pafford, Jr., Regional Director, Region 2 
 
 UNITED STATES BUREAU OF RECLAMATION 
 
 2800 Cottage Way, Sacramento, California 95825 
 
 Paul DeFalco, Jr., Regional Director, Pacific Southwest Region 
 WATER QUALITY OFFICE, ENVIRONMENTAL PROTECTION AGENCY 
 100 California Street, San Francisco, California 94111 
 
 John R. Teerink, Deputy Director 
 
 CALIFORNIA DEPARTMENT OF WATER RESOURCES 
 
 1416 Ninth Street, Sacramento, California 95814 
 
 June 1972 
 
 For sale by the Superintendent of Documents, U.S. Oovernment Printing Office, Washington, D.C. 20403 
 Price $1.26 domestic postpaid or $1 QPO Bookstore 
 
REVIEW NOTICE 
 
 This report has been reviwed by 
 the Water Quality Office, Environ- 
 mental Protection Agency and the 
 California Department of Water 
 Resources, and has been approved 
 for publication. Approval does 
 not signify that the contents 
 necessarily reflect the views and 
 policies of the Water Quality Office, 
 Environmental Protection Agency, or 
 the California Department of Water 
 Resources. 
 
 The mention of trade names or 
 commercial products does not 
 constitute endorsement or recom- 
 mendation for use by either of the 
 two federal agencies or the Cali- 
 fornia Department of Water Resources. 
 
 XI 
 
ABSTRACT 
 
 A nitrogen balance study of the San Luis Service Area determined 
 that the average annual nitrogen contributions from all sources 
 other than residual soil nitrogen were approximately equal to the 
 nitrogen removal by crops and volatilization losses. This would 
 indicate that, although in many instances the residual nitrogen 
 would replace some of the contributed nitrogen, especially fertil- 
 izers, animal and municipal wastes, the amount of nitrates moved 
 to the drains would be directly proportional to the amounts of 
 soluble, native nitrogen in the soil. 
 
 A soil sampling study at several sites throughout the area indica- 
 ted that there was a wide range in the concentrations of nitrates, 
 anunonia and organic nitrogen in the soils and subsoil. There were 
 extremely high concentrations of nitrates in those soils located 
 on the interfan positions between the larger streams. 
 
 Fertilizer studies in lysimeters show that in medium to heavy 
 textured soils under normal irrigation and fertilizer management 
 practices very little nitrogen fertilizer is leached to the drains. 
 Nitrate type fertilizer contributed more nitrogen to the drainage 
 effluent than ammonia and slow release sulfur coated urea fertili- 
 zers. 
 
 It was concluded that the best possibilities to reduce nitrogen in 
 drains by on farm practices will be to establish Farm Advisory 
 Programs to encourage the most efficient farm management and 
 fertilizer practices and, if found feasible, to design drain systems 
 to promote denitrif ication and reduce the area swept by the drain 
 flow lines. 
 
BACKGROUND 
 
 This report is one of a series which presents the findings of inten- 
 sive interagency investigations of practical means to control the 
 nitrate concentration in subsurface agricultural waste water prior 
 to its discharge into other water. The primary participants in the 
 program are the Federal Water Quality Administration, the United 
 States Bureau of Reclamation, and the California Department of 
 Water Resources, but several other agencies also are cooperating in 
 the program. These three agencies initiated the program because 
 they are responsible for providing a system for disposing of sub- 
 surface agricultural waste water from the San Joaquin Valley of 
 California and protecting water quality in California's water bodies, 
 Other agencies cooperated in the program by providing particular 
 knowledge pertaining to specific parts of the overall task. 
 
 The need to ultimately provide subsurface drainage for larg6 areas 
 of agricultural land in the western and southern San Joaquin Valley 
 has been recognized for some time. In 19 54, the Bureau of Reclam- 
 ation included a drain in its feasibility report of the San Luis 
 Unit, In 1957, the California Department of Water Resources initi- 
 ated an investigation to assess the extent of salinity and high 
 ground water problems and to develop plans for drainage and export 
 facilities. The Burns-Porter Act, in 1960, authorized S^n Joaquin 
 Valley drainage facilities as a part of the California Water Plan. 
 
 The authorizing legislation for the San Luis Unit of the Bureau of 
 Reclamation's Central Valley Project, Public Law 86-488, passed in 
 June 1960, included drainage facilities to serve project lands. 
 This Act required that the Secretary of Interior either provide for 
 constructing the San Luis Drain to the Delta or receive satisfactory 
 assurance that the State of California would provide a master drain 
 for the San Joaquin Valley that would adequately serve the San Luis 
 Unit. 
 
 Investigations by the Bureau of Reclamation and the Department of 
 Water Resources revealed that serious drainage problems already 
 exist and that areas requiring subsurface drainage would probably 
 exceed 1,000,000 acres by the year 2020, Disposal or tne drainage 
 into the Sacramento-San Joaquin Delta near Antioch, California, was 
 found to be the least costly alternative plan. 
 
 Preliminary data indicated the drainage water would be relatively 
 high in nitrogen. The Federal Water Quality Administration con- 
 ducted a study to determine the effect of discharging such drainage 
 water on the quality of water in the San Francisco Bay and Delta, 
 Upon completion of this study in 1967, the Administration's report 
 concluded that the nitrogen content of untreated drainage waters 
 could have significant adverse effects upon the fish and recreation 
 values of the receiving waters. The report recommended a three- 
 year research program to establish the economic feasibility of 
 nitrate-nitrogen removal. 
 
As a consequence, the three agencies formed the Interagency Agri- 
 cultural Wastewater Study Group and developed a three-year cooper- 
 ative research program which assigned specific areas of responsibil- 
 ity to each of the agencies. The scope of the investigation in- 
 cluded an inventory of nitrogen conditions in the potential drain- 
 age areas, possible control of nitrates at the source, prediction 
 of drainage quality, changes in nitrogen in transit and methods 
 of nitrogen removal from drain waters, including biological- 
 chemical processes and desalination. 
 
TABLE OF CONTENTS 
 
 Section Page 
 
 I Conclusion 1 ^ 
 
 II Introduction 3 ^ 
 
 III Literature Review 5 
 
 IV Methods and Procedure 7 
 
 Nitrogen Balance Study 7 ^ 
 
 Sources of Nitrogen Contribution 7 
 
 Nitrogen Fertilizers 9>^ 
 
 Mineralization of Organic Nitrogen 9 
 
 Irrigation Water 9 
 
 Rainfall 9 
 
 Leguminous Plants 9 
 
 Livestock 10 
 
 Municipal and Industrial 10 
 
 Nitrogen Losses from the Soil IQ-/ 
 
 Removal by Crops 10 
 
 Volatilization 10 
 
 Denitrif ication 11 
 
 Deep Percolation and Drainage 11 
 
 Lysimeter Studies 11 
 
 Transect Studies 15 
 
 Nitrate Concentrations in the Groundwater 17</ 
 
 V Results and Discussion 19 '^ 
 
 Nitrogen Budget 19 
 
 General 19 
 
 Nitrogen Contributions 21 
 
 Fertilizers 21"- 
 
 Irrigation Water 21 
 
 Wells 22 
 
 Canal Water 23 
 
 Stream and Flood Flow 23 
 
 Leguminous Plants 24 
 
 Rainfall 25 
 
 vii 
 
TABLE OF CONTENTS (Continued) 
 
 Section Page 
 
 Livestock 25 
 
 Municipal and Industrial 26 
 
 Nitrogen Losses 27 
 
 Removal by Crops 27* 
 
 Volatilization of Animonia Fertilizer 27 
 
 Denitrif ication 29 
 
 Nitrogen Budget Summary 29 
 
 Transect Study 30 
 
 Nitrogen in the Soil * 30 
 
 Nitrogen in the Substrata 35 
 
 Nitrogen in Groundwater 55 ' 
 
 0-50 Foot Well Depth 55 
 
 50-150 Foot Well Depth 61 
 
 150-300 Foot Well Depth 61 
 
 300-600 Foot Well Depth 61 
 
 600-800 Foot Well Depth 61 
 
 Nitrogen Transformation and Movement in Lysimeters. . . 62 
 
 Sources of Nitrogen to the Drain 74 
 
 Quantity of Nitrogen in the Drainage Effluent 77 
 
 Anticipated Changes in Nitrogen Sources 77^ 
 
 Fertilizer Usage 77 
 
 Future Crop Pattern 78 
 
 Leaching Native Nitrogen 78 
 
 Increase in Municipal and Industrial Waste 79 
 
 Control of Nitrogen at the Source 80 
 
 Farm Advisory Program 80 
 
 Soil Management 80 
 
 Fertilizer Management 80 
 
 Water Management 81 
 
 Crop Management 81 
 
 Specially Designed Farm Drain Systems 81 
 
 VI References 82 
 
 viii 
 
FIGURES 
 
 Number Page 
 
 1 San Luis Service Area - Nitrogen Transect Sites 8 
 
 2 Layout Of Lysimeters - Nitrogen Movement Studies 12 
 
 3 Instrument Layout - Lysimeter Number 7 14 
 
 4 Distribution of NO3-N, NH3-N and Organic -N by 
 
 Sampling Depth 42 
 
 5 Distribution of NO3-N, NH^-N and Organic -N by 
 
 Sampling Depth 43 
 
 6 Distribution of NO3-N, NH,-N and Organic -N by 
 
 Sampling Depth 44 
 
 7 Distribution of NO3-N, NH3-N and Organic -N by 
 
 Sampling Depth 45 
 
 8 Distribution of NO,-N, NH3-N and Organic -N by 
 
 Sampling Depth 46 
 
 9 Distribution of NO3-N, NH3-N and Organic -N by 
 
 Sampling Depth 47 
 
 10 Distribution of NO3-N, NH3-N and Organic -N by 
 
 Sampling Depth 48 
 
 11 Distribution of NO3-N, NH3-N and Organic -N by 
 
 Sampling Depth 49 
 
 12 Distribution of NO3-N, NH3-N and Organic -N by 
 
 Sampling Depth 50 
 
 13 Distribution of NO3-N, NH3-N and Organic -N by 
 
 Sampling Depth 51 
 
 14 Distribution of NO3-N, NH3-N and Organic -N by 
 
 Sampling Depth 52 
 
 15 Distribution of NO3-N, NH3-N and Organic -N by 
 
 Sampling Depth 53 
 
 16 Distribution of NO3-N, NH3-N and Organic -N by 
 
 Sampling Depth 54 
 
 17 Movement of Nitrates in Soil Column 72 
 
 18 Movement of Chlorides in Soil Column 73 
 
 ix 
 
TABLES 
 Number Page 
 
 1 Nitrogen Contributed by Fertilizer 1968 22 
 
 2 Total Nitrogen Contribution from Irrigation Water 
 
 1968 and Ultimate 23 
 
 3 Average Annual Nitrogen Contribution by Local 
 
 Streams 24 
 
 4 Nitrogen Contribution from Leguminous Plants - 1968... 25 
 
 5 Nitrogen Contributions for Animals - 1968 26 
 
 6 Removal of Nitrogen by Harvested Crop - 1968 28 
 
 7 Nitrogen Budget - 1968 30 
 
 8 Quantities of Various Forms of Nitrogen at Transect 
 
 Site as Determined from 1:1 Soil-Water Extracts 31 
 
 9 Minimum, Maximum and Average NO3-N and Organic -N 
 
 Concentrations at the Various Sites by Soil Type 
 
 0-5 Feet 34 
 
 10 The Average NO3-N and Organic -N Content in Parts Per 
 
 Million in the 0-5 Foot Increment for the 5 Holes 
 Within the Various Sites 36 
 
 11 Summary of NO3-N in Parts Per Million, Standard 
 
 Deviations and Standard Error of Mean for the Five 
 Holes at each Nitrate Site 37 
 
 12 Average Pounds Per Acre and Total N in the Study Area 
 
 in 0-5 Foot Soil Depth 39 
 
 13 NO3-N, NH3-N and Organic N in PPM and Pounds Per Acre 
 
 Feet in the Soil Substrata 40 
 
 14 Total N in the 5-40 Foot Substrata by Alluvial Fan 41 
 
 15 Summary of Nitrate Nitrogen and Standard Deviations 
 
 in Milligrams per Liter for Wells and USBR Geohydro- 
 
 logic Observation Hole above the Corcoran Clay - 
 
 0-50 Foot Depth 56 
 
TABLES (Continued) 
 Number Page 
 
 16 Sununary of Nitrate Nitrogen and Standard Deviations 
 
 in Milligrams Per Liter for Wells and USER Geohydro- 
 
 logic Observation Holes above the Corcoran Clay - 
 
 50-150 Foot Depth 57 
 
 17 Summary of Nitrate Nitrogen and Standard Deviations 
 
 in Milligrams Per Liter for Wells and USER Geohydro- 
 logic Observation Holes above the Corcoran Clay - 
 150-300 Foot Depth 58 
 
 18 Summary of Nitrate Nitrogen and Standard Deviations 
 
 in Milligrams per Liter for Wells and USER Geohydro- 
 logic Observation Holes above the Corcoran Clay - 
 300-600 Foot Depth 59 
 
 19 Summary of Nitrate Nitrogen and Standard Deviations 
 
 in Milligrams Per Liter for Wells and USER Geohydro- 
 logic Observation Holes above the Corcoran Clay - 
 600-800 Foot Depth 50 
 
 20 Nitrogen Content and Percent of Fertilizer Nitrogen in 
 
 Soil Extracts from "A" Depths, December 16, 1968 - 
 August 8 , 1969 63 
 
 21 Nitrogen Content cind Percent of Fertilizer Nitrogen in 
 
 Soil Extracts from "E" Depths, December 16, 1968 - 
 August 8 , 1969 63 
 
 22 Nitrogen Content and Percent of Fertilizer Nitrogen in 
 
 Soil Extracts from "C" Depths, December 16, 1968 - 
 August 8 , 1969 64 
 
 23 Nitrogen Content and Percent Fertilizer N in the Leachate 
 
 December 16, 1968 - August 1, 1969 64 
 
 24 Total Nitrogen Content of Soil Extracts, Leachates and 
 
 Percent Fertilizer N - for the Period December 13, 
 
 1968 to August 18 , 1969 65 
 
 25 Recovery of Fertilizer Nitrogen from all Probes and 
 
 Leachate for the Period - December 16, 1968 - 
 
 August 18 , 1969 66 
 
 26 Nitrate -N Recovered in the Leachate of Soil Columns 
 
 for the Period December 16, 1968 - August 18, 1969... 66 
 
 xl 
 
TABLES (Continued) 
 Number Page 
 
 27 Recovery of Applied Fertilizer Nitrogen in the Barley 
 
 and Grain Sorghum 67 
 
 28 Recovery of Applied Fertilizer N in Barley, Grain 
 
 Sorghum and Water Samples 68 
 
 29 Recovery of Applied Fertilizer Nitrogen in the Nitrate 
 
 and Organic Nitrogen Fraction from Two Lysimeters. . . 69 
 
 30 Summary of Applied -^% Collected in the Various 
 
 Categories 70 
 
 31 Nitrogen Balance Sheet - Lysimeter Number 6 75 
 
 xii 
 
SECTION I 
 CONCLUSIONS 
 
 1. The major source of the nitrogen in the drainage effluent in 
 the San Luis Service Area is the nitrogen that is native to the 
 soils and subsoils. 
 
 2. Under normal soil, cropping, irrigation and fertilizer condi- 
 tions of this area, only a small percentage of the applied fertil- 
 izer nitrogen will reach the drainage effluent; however, in a few 
 small areas of light soils, where excessive irrigation water and 
 fertilizers were applied or the fertilizer application is ill-placed 
 and timed, larger amounts of nitrogen may be leached into the 
 drainage water. 
 
 3. There will be local areas of high nitrate concentration adjacent 
 to municipal sewage disposal plants and possibly near cattle feed 
 lots. 
 
 4. The reduction of the quantity of nitrogen reaching the drains 
 by controls at the source could be implemented by: 
 
 a. An advisory program conducted by the Extension Service and 
 other agencies to encourage: 
 
 (1) the most efficient rate, type, time and method of 
 fertilizer applications. 
 
 (2) irrigation practices to control excess deep percola- 
 tion of applied water. 
 
 (3) crop and soil management practices to minimize nitrogen 
 losses . 
 
 b. If research studies on the design of drainage systems to 
 reduce nitrogen in drainage effluent prove feasible, systems 
 should be installed to: 
 
 (1) encourage denitrif ication by maintaining anaerobic 
 conditions with submerged drains. 
 
 (2) reduce the area swept by the drain flow lines by 
 decreasing the depth and spacing of tile lines. 
 
 (1) 
 
SECTION II 
 
 INTRODUCTION 
 
 As a result of the application of large quantities of water to 
 relatively slowly permeable stratified soils, the west side of the 
 San Joaquin Valley now has large areas with groundwater at rootzone 
 depths. These areas, requiring drainage to maintain productivity, 
 will increase in size as more water is imported. Wherever sub- 
 surface drains have been installed to control this groundwater, the 
 drainage effluent has had high nitrate concentrations. Investiga- 
 tions were conducted to determine the source of this nitrogen, its 
 form and quantity in the soil, its distribution, and whether its 
 entry into the drains can be controlled or limited. 
 
 Large quantities of inorganic nitrogen fertilizers are applied 
 annually and the assumption prevails that fertilizer is the major 
 source of nitrates in the drainage water. The study reported 
 herein was designed to evaluate this assumption and to derive, if 
 possible, practical answers regarding the role of on-farm practices 
 in controlling nitrate out-put from the agricultural lands. This 
 portion of the study was confined to the San Luis Service Area, a 
 part of the west side of the San Joaquin Valley comprising about 
 569,000 acres. The area is centrally located with respect to 
 present and ultimate drainage areas and was judged to be reasonably 
 representative of the major areas contributing to drainage. 
 
 This study examines the nitrogen budget and investigates methods 
 for reducing the quantity of nitrates in the drainage effluent by 
 modifications in type or use of fertilizers, farming practices, or 
 drainage techniques. To accomplish these objectives it was necessary 
 to: 
 
 1. Identify the major sources of soil or water nitrogen 
 which contribute to the drainage effluent. 
 
 2. Determine the quantities of nitrates that these sources 
 contribute to the drainage effluent. 
 
 3. Determine if control of nitrates at the source is needed 
 and if so how can it be accomplished. 
 
 (3) 
 
SECTION III 
 
 LITERATURE REVIEW 
 
 The source, movement and fate of nitrogen in soils and water have 
 been the subject of many studies. Tisdale and Nelson (1) describe 
 the various biochemical processes of the nitrogen cycle which occur 
 in soils and their relation to soil fertility. 
 
 Stout and Burau (2) compared the accumulation of mobile nitrogen 
 in uncultivated fields with heavily irrigated fields in the Grover 
 City-Arroyo Grande Basin. They found that in permeable soils, 
 nitrate concentrations in the range of 100 p. p.m. would accumulate 
 in the water percolating to the groundwater table, whether unculti- 
 vated or cultivated, and with or without fertilization. Doneen, 
 (3) in a study of irrigated fields in the Firebaugh area, states 
 that nitrate-nitrogen in the effluent is principally from three 
 sources; (1) soil organic matter; (2) originally in the soil profile 
 or ground water before irrigation, and (3) fertilizers. The losses 
 of nitrates from the soil and groundwater are in three general 
 categories: (1) removed in the harvested crop, (2) by denitrifica- 
 tion, and (3) in the drainage water. 
 
 Various studies by Terman (4), Martin and Chapman (5), and Harding 
 (6) conclude that if ammonia or urea types of fertilizer are applied 
 to the surface of warm, moist alkaline soils which are present in 
 this area, there will be large losses of the nitrogen by volatiliza- 
 tion in the form of NH3. However, if the fertilizer is placed a 
 few inches below the soil surface either by tillage or by dissolving 
 in the irrigation water the losses can be minimized. 
 
 Significant quantities of nitrogen, primarily in the form of NH? 
 and NO?, enter the soil dissolved in the rain waters. Studies by 
 Junge (7), Gambel and Fisher (8) suggest that in the San Luis Area 
 the average concentrations of these ions are about 0.1 mg/1 eacn. 
 They believe the major sources of these N-forms are from the volatili- 
 zation of the nitrogen from the soil surface or from industrial 
 plants. 
 
 Well water will continue to be a major source of irrigation water 
 for the area. The nitrate concentrations for waters from selected 
 wells in the area were measured and are described by a U. S. Geo- 
 logical Survey open file report (9). The nitrate content of these 
 wells ranged from to 98 mg/1 with an average of about 2 mg/1. 
 An analysis of the distribution of nitrates in the water strata 
 above the Corcoran formation in the Sierran and Coast Range sediments 
 is presented in a study by the Groundwater Section of the Geology 
 Branch, U.S.B.R. in Sacramento (10). The NO^ concentration in these 
 strata ranged from less than 1 to more than 542 mg/1. There were 
 higher concentrations in the Coast Range Sediments than in the Sierran 
 and a reduction of concentrations with depth. 
 
 (5) 
 
Leguminous plants are a source of nitrogen to the soil. Bartholomew 
 and Clark (11) and Erdman (12) found that under normal conditions 
 these plants fix from a few pounds to more than 300 pounds per acre 
 annually. The majority of this nitrogen is used to produce the 
 crop which is harvested and is not returned to the soil. 
 
 The waste from animals can make an appreciable contribution to the 
 nitrogen supply of an area, especially when the animals are con- 
 centrated in feed or dairy lots. Leohr (13) gives the waste 
 characteristics of various types of livestock and humans. These 
 characteristics include the amount of nutrients and pollutants, 
 and the chemical and biochemical oxygen demand of the waste. He 
 also presents possible methods to treat or dispose of the waste. 
 
 The major loss of nitrogen from the soil occurs through the removal 
 of nitrogen by the crops. Morrison's "Feeds and Feeding" (14) lists 
 the percent of nitrogen in the various crops from which the amount 
 of removal can be estimated. The average nitrogen content of the 
 crops grown in this area varies from a high of 5.31 percent for 
 alfalfa seed to a low of ,12 percent for vineyards. The major crops, 
 cotton and grain, contain 2.92 and 1.39 percent, respectively. 
 
 (6) 
 
SECTION IV 
 
 METHODS AND PROCEDURES 
 
 This section describes the methods and procedures used in the 
 various phases of the nitrogen balance study. 
 
 Nitrogen Balance Stud y 
 
 A nitrogen balance study was made of the San Luis Service Area, the 
 boundary of which is delineated in Figure 1. The budget is impor- 
 tant in that it is to be used to identify the quantities of nitrogen 
 which might be controlled through modified farm practices. 
 
 The nitrogen balance was made by comparing the estimated annual 
 contributions to the crop root zone of the soil with estimated 
 annual losses that could be identified. Because of the many com- 
 plexities of the system, it is difficult to determine if the 
 quantities of nitrogen measured in the soil are at equilibrium with 
 the contributions and losses; however, available data indicate that 
 near equilibrium exists. No attempt was made to extend the budget 
 through the substrata and groundwater, however, from data in the 
 study it is noted that in some areas the nitrogen increases down 
 to shallow groundwater, but is markedly less in the deep ground- 
 water. Anticipated changes in the nitrogen regime are also dis- 
 cussed in this study. 
 
 Sources of Nitrogen Contribution 
 
 The major sources of nitrogen, other than the naturally occurring 
 mineral forms in the soils, that contribute to the system are: 
 
 1. Nitrogen fertilizers 
 
 2. Mineralization of organic nitrogen compounds 
 
 3 . Irrigation water 
 
 4. Stream and flood flows 
 
 5. Rainfall 
 
 6. Leguminous plants 
 
 7. Livestock 
 
 8. Municipal and industrial wastes 
 
 Many authorities consider non-symbiotic nitrogen fixation to be a 
 contributor; however, very little is known about the quantities 
 supplied under field conditions because they are too small to be 
 measured (15). Therefore, this source was not included in this 
 study . 
 
 The methods used to determine the contribution of each category are 
 listed below: 
 
 (7) 
 
© 
 
 L EGEND 
 
 - Son Luis Service Area Boundary 
 
 - Alluvial Fon Boundaries 
 
 - Nitrogen Transect Sites 
 
 GEOMORPHIC AREAS 
 A.- Laguna Seca- Little Panoche Creek Interfan 
 B. - Little Panoche Creek Fan 
 C- Little Panoche -Panoche Creek Interfan 
 D- Panoche Creek Fan 
 E — Panoche -Contua Creek Interfan 
 F- Cantuo Creek Fan 
 G- Cantuo - Los Gatos Interfan 
 H- Los Gotos Creek Fan 
 I.- Los Gatos Creek — Interfan (South) 
 
 FIG. I - SAN LUIS SERVICE AREA 
 NITROGEN TRANSECT SITES 
 
 (8) 
 
Nitrogen Fertilizers : The quantity of nitrogen applied in the 
 fertilizer was determined for 1968 and estimated for the ultimate 
 development. This determination was made from the amount applied 
 per acre to each crop and the total number of acres of the various 
 crops. The average application rates were based on Farm Advisors 
 and fertilizer consultants recommendations and field sampling of 
 actual farming practices. The amount applied depended on such factors 
 as soil type, crop history, crop involved and the judgement of the 
 grower . 
 
 The acreage devoted to the various crops in 1968 was determined from 
 a crop survey made by the State of California, Department of Water 
 Resources. The projection of the acreage of the various crops under 
 ultimate development conditions was prepared by the U.S. Bureau of 
 Reclamation. 
 
 Mineralization of Organic Nitrogen : The mineralization of 
 organic nitrogen compounds is accomplished by various types of micro- 
 organisms. The amount of ammonia and nitrates released by this process 
 depends upon many factors but in general the environmental factors 
 favoring the growth of most agricultural plants are those that also 
 favor the activity of the nitrifying bacteria. The estimates of the 
 quantities of the mineral nitrogen released in these reactions were 
 based on data derived from the literature. 
 
 Irrigation Water : The quantity of nitrogen applied by the 
 irrigation water was determined from the amount of water applied 
 and the nitrate concentration of the applied water. The water applied 
 was calculated from the farm irrigation requirement multiplied by 
 the acreage of each crop. The nitrate concentration of the water 
 was determined by caJculating the weighted average of the ground- 
 water and the canal water as taken from the chemical analyses of the 
 wells in the area (9) and from State of California, Department of 
 Water Resources data. 
 
 Rainfall ; The ainount of nitrogen supplied by rainfall was 
 determined from the average precipitation in the area as taken from 
 Weather Burau data and the nitrogen concentration in the rain water. 
 This value was derived from work by Junge (7) and Gambel and Fisher 
 (8). 
 
 Leguminous Plants : Certain plants in a symbiotic relationship 
 with various species of the Rhizobium bacteria will fix elemental 
 nitrogen. Alfalfa and beans are the legumes grown in this area. 
 ! The amount of nitrogen fixed by these crops will vary greatly but 
 ; based on the work of Erdman (12), it is estimated that alfalfa will 
 ! fix an average of 194 pounds per acre and beans 40 pounds per acre 
 I per year. The acreage of these crops was determined from the 1958 
 crop survey and the estimated ultimate acreage was taken from Bureau 
 of Reclamation studies. 
 
 (9) 
 
Livestock : The nitrogen contribution by the livestock was 
 taken from the numbers of each type and the waste characteristics 
 of each species. The number of cattle in the area was determined 
 from information supplied by the major feed lots of the area for 
 the 1968 season. The sheep population was estimated from data 
 reported in the 1968 Fresno County Agricultural Report. The number 
 of other livestock in the area is not significant. The waste 
 characteristics of the animals were taken primarily from the work 
 of R. C. Loehr (13). 
 
 Municipal and Industrial : This area is sparsely inhabited with 
 the majority of the population centered in several small communities, 
 a number of large labor camps, and the Lemoore Naval Air Station. 
 There are a few agriculture oriented industries in the area. Pop- 
 ulation figures were estimated from census data supplied by the 
 Fresno County Planning Department. The amount of nitrogen waste 
 contributed by the inhabitants of the area was calculated from data 
 derived from work by Loehr (13). The industrial wastes were deter- 
 mined from field estimates made in the various communities. 
 
 Nitrogen Losses from the Soil 
 
 The main categories of nitrogen loss in this area are: 
 
 1. Removal by crops 
 
 2. Volatilization 
 
 3. Denitrif ication 
 
 4. Deep percolation and drainage 
 
 Wind and water erosion is a major factor in nitrogen removal in 
 some areas, however, in the study area losses by such physical 
 removal are not significant because of relatively level lands, low 
 rainfall, and light winds. The methods used in determining the loss 
 by each category are presented below: 
 
 Removal by Crops : The major loss of nitrogen is through removal 
 from the soil by the growing plants. The quantity removed in this 
 way was calculated from the number of acres of each crop grown as 
 determined from the 1958 crop survey and the estimated amount of 
 nitrogen in the various plant materials as determined primarily 
 from Morrison's "Feeds and Feeding" (14). 
 
 Volatilization ; The loss of nitrogen by volatilization of 
 ammonia and urea type fertilizers was calculated from the amount 
 of those fertilizers applied multiplied by 5 percent, the estimated 
 amount of N volatilized. This value was determined from the lab- 
 oratory and field studies made on the subject (4)(5) correlated 
 with local soil conditions and farming practices. 
 
 (10) 
 
Denitr if ication ; Elemental nitrogen gas and/or nitrous oxide 
 are released through denitrif ication, the biochemical reduction of 
 nitrates under anaerobic conditions. The conditions under which 
 this process occurs are so variable and difficult to measure in the 
 field that no meaningful estimate of the actual values can be made. 
 Therefore, for this study, it is recognized that losses under certain 
 conditions could be significant but no numerical values were assigned. 
 
 Deep Percolation and Drainage ; The nitrates that are present in 
 the soil system, either native, mineralized, or added, that are not 
 removed by the crop, volatilized, denitrified, or immobilized by 
 conversion to other nitrogen compounds will move with the percolating 
 water where eventually they will either be picked up in the drains or 
 moved into the groundwater. The rate nitrates enter the drains or 
 groundwater for any given period would be the difference between the 
 nitrates contributed and the amount immobilized or removed by processes 
 other than percolation divided by the time required to move the nitrates 
 through the soil profile. 
 
 Lysimeter Studies 
 
 Lysimeters were operated in Fresno at the Bureau of Reclamation Soils 
 Laboratory to study the movement of nitrogenous fertilizers in soil 
 columns. Eighteen columns made of techite (fiber glass) pipe 15 inches 
 in diameter and 6.7 feet in length were filled with four major soil 
 types developed on the westside of the San Joaquin Valley of California 
 from sediment of the Coast Range Mountains. Five columns were filled 
 with Panoche fine sandy loam, a recent alluvial, light textured, slightly 
 saline soil. Four columns were filled with Panoche silty clay loam and 
 three columns were filled with Panoche clay loam soils similar to the 
 above soils except somewhat finer in texture. Three columns were filled 
 with Oxalis Clay, a fine textured. soil, slightly to moderately compacted 
 in the subsoil, and moderately saline. Three columns were filled with 
 Lethent sandy clay loam, a basin rim soil with medium textured surface 
 over a moderately compacted fine textured subsoil with moderate to 
 strong concentration of alkaline and saline salts. The soils were screened, 
 weighed, aurid placed in the columns and tamped to approximately field 
 density. 
 
 The surface and subsurface soil material of the Panoche fine sandy loam, 
 and the Oxalis clay soils were mixed in the lysimeters. The soil material 
 from the Panoche clay loam and the Lethent soils were placed in layered 
 horizons in the same sequence as in the natural condition. A layout of 
 the lysimeters is shown as Figure 2. 
 
 (11) 
 
PANOCHE CL 
 
 PANOCHE CL 
 
 PANOCHE CL 
 
 PANOCHE FSL 
 
 LETHENT SCL 
 
 PANOCHE FSL 
 
 PANOCHE SI CL 
 
 OXALIS CLAY 
 
 PANOCHE FSL 
 
 LETHENT SCL 
 
 PANOCHE FSL 
 
 PANOCHE SI CL 
 
 OXALIS CLAY 
 
 PANOCH E FSL 
 
 LETHENT SCL 
 
 PANOCHE SI CL 
 
 PANOCHE SI CL 
 
 OXALIS CLAT 
 
 r 
 
 A- 
 
 FIG. 2 -LAYOUT OF LYSI M E TERS - Nl TROGEN MOVEMENT STUDIES 
 
 (12) 
 
The lysimeters were instrumented with tensiometers, soil extract 
 suction probes, and soil moisture and temperature cells. These 
 instruments were placed in the soil columns by drilling holes 
 through the sides of the lysimeters and inserting the instruments 
 near the center of the soil columns. Generally four mercury type 
 tensiometers were located in each lysimeter at approximately 18, 
 30, 42, and 54 inch depths. Three each of the soil extract suction 
 probes and the soil moisture and temperature cells were installed 
 at approximately 12, 24 and 60 inch depths. A typical layout of 
 one lysimeter is shown in Figure 3. When the lysimeters were filled, 
 sufficient water was applied to the columns to bring the soils to 
 field capacity and to start water draining from the lysimeters. 
 After the columns started to drain, water was added in 4-inch 
 increments every two weeks to leach the nitrates to a relatively 
 constant level. 
 
 Soil extracts were collected from the suction probes at varying 
 time periods, depending on the needs of the program, by applying 
 approximately 14 pounds of suction with a vacuum pump. Samples 
 of the effluent draining from the bottom of the lysimeters were 
 collected on the same schedule as the soil extracts. 
 
 The volumes extracted from the probes and collected in the leach- 
 ates were recorded. All of the samples were analyzed for nitrates, 
 electrical conductivity and pH. Some of the samples were analyzed 
 for chlorides, ammonia, total nitrogen and percent excess -"^N. 
 (an isotope of nitrogen with a mass number of 15) 
 
 The leaching program was continued until December 1968. At this 
 time, the nitrate concentrations in most of the lysimeters, although 
 varying with soil type, were reduced to a fairly constant level. 
 Barley was planted in the lysimeters and three different types of 
 nitrogenous fertilizers were applied - (NH4)2S04 and KNO? , both 
 fast nitrogen release types, and sulfur coated urea, a slow nitrogen 
 release type. The fertilizers were applied at a rate equivalent 
 to 100 pounds N per acre or 12 50 milligrams of N per lysimeter. 
 The (NH4)2S04 and the KNO3 fertilizers were eniched with approxi- 
 mately 10 percent ^^N and the urea with 28.2 percent ^^ti . The 
 (NH4)2S04 was applied to two lysimeters filled with Panoche clay 
 loam and two filled with Oxalis clay. The KNO3 was applied to two 
 soil columns of Panoche fine sandy loam and two of Lethent sandy 
 clay loam. Sulfur coated urea was applied to two columns of 
 Panoche fine sandy loam. A control to which no fertilizers were 
 applied was maintained for each soil type. Samples from the suc- 
 tion probes and the leachates were collected, frozen and sent to 
 
 (13) 
 
Tensionmeter 
 Hg Surface 
 
 } I I \ 1 
 
 .21 
 
 Suction Probes 
 
 a 
 
 Soil Moisture Cells 
 
 ,, 
 
 0.92 
 
 .87' 
 
 5.03' 
 
 Soil Surfoce 
 
 t/Mu^»mu%tMt 
 
 046 
 
 3.29' 
 
 4.18' 
 
 5.21 
 
 6.13' 
 
 FIG. 3- INSTRUMENT LAYOUT LYSIMETER NOT 
 
 ' 14) 
 
the University of Arizona for analysis of nitrate and atom percent 
 excess ^^H , the amount of -'-% in excess of that which occurs 
 naturally. 
 
 The barley was irrigated at approximately the rate that the farmers 
 of the area use in their normal field operations. The soils were 
 at field capacity when seeded and additional applications of water 
 totaling 19.2 inches were applied during the growing season. The 
 irrigation water applied was obtained from a well at the University 
 of California Westside Field Station near Five Points. This water 
 contained approximately 2 mg/1 of NO3 and 1,000 mg/1 of total 
 dissolved solids. 
 
 After the barley was harvested in May, eight inches of water were 
 applied to the lysimeters. This amount brought the soils to field 
 capacity and started drainage from the columns. The lysimeters 
 were planted to sorghum without additional fertilization. In 
 addition to the preirrigation of eight inches a subsequent 25.4 
 inches of water were applied during the growing season. The sorghum 
 was harvested in October 1969. 
 
 Grain from the barley and sorghum crops was weighed and analyzed 
 separately from the straw or stover. All plant samples were dried, 
 ground, and analyzed for total nitrogen by standard micro-Kjeldahl 
 procedures. After titration, the ammonia was redistilled and atom 
 percent excess % determined. 
 
 In addition to those lysimeters used in the plant studies, four 
 columns filled with Panoche silty clay loam were employed to study 
 the movement of nitrogen salts in a non-cropped, moist but unsat- 
 urated moisture regime. On January 20, 1969, Ca(N03)2 was applied 
 to the soil columns at a rate equivalent to 100 pounds of nitrogen 
 per acre. At the same time, CaCl2 was applied as a source of CI to 
 serve as a tracer element for the NO-,. Water was applied at the 
 rate of four inches every two weeks. Samples of the soil extract 
 were collected from the suction cups at four depths in the column 
 and the effluent which passed through the column was collected from 
 the bottom of the lysimeter. The samples collected were analyzed 
 for nitrates, pH, electrical conductivity and chlorides. Addition- 
 al analyses for NH4 , NO2 and organic N were run on a number of the 
 samples. When it was evident that the first application of salts 
 had moved through the columns NH4CI was applied to the columns and 
 the movement of this salt monitored as it moved downward through 
 the soil. The moisture regime was monitored by four mercury type 
 tensiometers in each lysimeter at depths of approximately 12, 24, 
 36, and 48 inches. 
 
 Transect Study 
 
 A series of borings was made along several lines transecting the 
 San Luis Service Area generally from east to west. The purpose of 
 
 (15) 
 
this study was to determine the quantity and distribution of the 
 various nitrogen forms, by area and by depth, and to determine the 
 variability of nitrogen in soils of similar type within small areas. 
 
 Thirteen sites were selected along four lines transecting the area. 
 The sites were selected to be representative of the different soil 
 series, physiographic and geomorphic positions. The soil type, 
 physiographic position, and alluvial fan location of each of the 
 sites were as follows: 
 
 Hole No. Soil Type 
 
 Physiographic Position Geomorphic Position 
 
 1 
 
 Oxalis SiC 
 
 Basin Rim 
 
 Los Gatos Creek Fan 
 
 2 
 
 Lethent SiC 
 
 Basin Rim 
 
 Los Gatos Creek Fan 
 
 3 
 
 Panoche C L 
 
 Recent Alluvial 
 
 Los Gatos Creek Fan 
 
 4 
 
 Panoche SiC 
 
 Recent Alluvial 
 
 Los Gatos Creek 
 Interfan 
 
 5 
 
 Oxalis C 
 
 Basin Rim 
 
 Los Gatos Creek 
 Interfan 
 
 6 
 
 Lethent C 
 
 Basin Rim 
 
 Los Gatos Creek 
 Interfan 
 
 7 
 
 Levis C 
 
 Basin Rim 
 
 Cantua-Panoche Creek 
 Interfan 
 
 8 
 
 Oxalis Si C 
 
 Basin Rim 
 
 Cantua-Panoche Creek 
 Interfan 
 
 9 
 
 Panoche Si C 
 
 Recent Alluvial 
 
 Cantua-Panoche Creek 
 Interfan 
 
 10 
 
 Lost Hills Si 
 
 C Older Alluvial 
 
 Cantua-Panoche Creek 
 Interfan 
 
 11 
 
 Panoche C L 
 
 Recent Alluvial 
 
 Panoche Creek Fan 
 
 12 
 
 Panoche Si C 
 
 Recent Alluvial 
 
 Panoche Creek Fan 
 
 13 
 
 Oxalis C 
 
 Basin Rim 
 
 Panoche Creek Fan 
 
 The locations of the sites are shown on Figure 1. At each of the 
 sites, five holes were bored on a line 50 feet apart. Three holes 
 were drilled to a depth of five feet, one hole to ten feet, and one 
 hole to the water table or 40 feet, whichever occurred first. The 
 soil material in each hole was logged in the field for texture, 
 moisture, permeability, lime, mottling, compaction, structure and 
 temperature . 
 
 Two sets of soil samples were collected from each hole. One of the 
 sets was stored in a freezer where it was kept frozen to prevent 
 bacterial activity until the laboratory analyses for the various 
 nitrogen constituents could be made. The other set was delivered to 
 the Regional Soils Laboratory where determinations were made for 
 calcium, magnesium, sodium, carbonates, bicarbonates, sulphates, 
 chlorides, boron, gypsum, lime, pH, saturation percentage, cation 
 exchange capacity, exchangeable sodium percentage and total dissol- 
 ved solids. Analytical methods for these tests were based on the 
 
 (16) 
 
Bureau of Reclamation laboratory instructions. (15) 
 
 Nitrogen analyses were made for nitrates, ammonia and total organic 
 nitrogen. The nitrates were determined by the specific ion meter, 
 ammonia by distillation and titrating with H2SO4 and the total 
 organic nitrogen by the standard micro-Xjeldahl procedure. 
 
 Infiltration rate and hydraulic conductivity were determined at 
 the site. The bulk density and porosity were calculated from core 
 samples taken with a split ring density sampler. The infiltration 
 rates were by means of a constant head, double ring inf iltrometer. 
 The hydraulic conductivities were determined by the auger hole 
 and shallow well pump-in methods. 
 
 A statistical analysis was made of the nitrates, ammonia, and 
 organic nitrogen data to determine the variability of these various 
 constituents within a small area of a similar soil type. The 
 arithmetic average, the standard deviation of the mean and the 
 standard error of the mean were calculated for the data from the 
 upper five feet of the thirteen sites. 
 
 The mineral analyses and the tests for the soil physical properties 
 were primarily made to obtain basic data for a prediction model 
 study. 
 
 Nitrate Concentrations in the Groundwater 
 
 Studies of the nitrate concentration in the groundwater of the area 
 have been made by various agencies. Included in these studies are 
 work by the U. S. Bureau of Reclamation, U. S. Geological Survey, 
 and State of California, Department of Water Resources. The Bureau 
 of Reclamation, California Department of Water Resources and West- 
 lands Water District entered into a cooperative agreement with the 
 U. S. Geological Survey to collect and make chemical analyses of 
 wells in the Dos Palos-Kettleman City area. Between July 15 and 
 September 20, 1968, water samples were collected from 361 wells in 
 the area. The analyses of the samples provided the majority of the 
 data for this study. These analyses, along with the descriptive 
 well data and well location are presented in the U. S. Geological 
 Survey open file report. (9) These data were supplemented with an 
 additional 180 samples collected and analyzed by the Bureau of 
 Reclamation's Fresno office. 
 
 Employing data from the wells and the U. S. B. R. geohydrologic test 
 holes nitrate in parts per million was plotted above the Corcoran 
 Clay by depth of well, geomorphic area and ty the Sierra or Coast 
 Range sediments. The arithmetic mean and standard deviation was 
 computed by well depth intervals 0-50, 50-150, 150-300, 300-600 and 
 600-800 feet, on the analyses of nitrates in wells above the Cor- 
 coran Clay. Where the number of samples in any interval was less 
 than thirty, the standard deviation was computed from the mean 
 
 (17) 
 
using one sample less (N-1) than the number used to obtain the 
 arithmetic mean (N). 
 
 (18) 
 
SECTION V 
 
 Results and Discussion 
 
 This section discusses the results and findings of the several field 
 and lysimeter investigations on nitrogen balance, residual nitrogen 
 in field soils and the movement of applied fertilizer nitrogen. 
 
 Nitrogen Budget 
 
 This nitrogen balance study was based on average soil, farming, and 
 irrigation conditions in the area. However, it should be recognized 
 that because of the large size and variable conditions of the area 
 many of the soils will deviate appreciably from the norm, therefore, 
 there will be local areas that will vary significantly from the 
 average values presented here. Precise measurements cannot be ob- 
 tained under ordinary field conditions, nevertheless these data do 
 supply information that is sufficiently quantitative to show the 
 magnitude of the main soil nitrogen losses and gains. 
 
 GENERAL 
 
 The nitrogen cycle consists of a series of continuous processes in- 
 volving the plants, animals and micro-organisms of the soil and air 
 through which the elemental nitrogen moves in the eco-system. The 
 processes involved as they effect the appearance of nitrogen in the 
 drainage water is the concern of this study. Knowledge of the 
 processes in the nitrogen cycle is essential to understanding and 
 dealing with nitrogen in the drainage effluent. 
 
 The ultimate source of nitrogen is the inert gas N2, which consti- 
 tutes about 78 percent of the earth's atmosphere. In its elemental 
 form it is useless to higher plants therefore it must be converted 
 to usable forms. Although it may be recycled and delivered in many 
 forms, the basic processes by which nitrogen is converted to usable 
 forms and gains entrance to the soils are: 
 
 1. Fixation by Rhizobia and other micro-organisms which live 
 symbiotically on the roots of legumes and certain non- 
 leguminous plants. 
 
 2. Fixation by free-living soil micro-organisms and perhaps 
 by organisms living on the leaves of tropical plants. 
 
 3. Fixation as one of the oxides of nitrogen by atmospheric 
 electrical discharges. 
 
 4. Conversion to ammonia, nitrate, urea by any of the various 
 industrial processes for the manufacture of synthetic 
 nitrogen fertilizers. 
 
 (19) 
 
Plants adsorb most of their nitrogen as NO^ or NH4 which in the 
 growth process of the plant are converted to an organic form. Much 
 of this organic nitrogen is reincorporated into the soil by plowing 
 the plant material back into the soil or through the application of 
 animal manures to the soil. These organic forms of soil nitrogen 
 occur as consolidated amino acids or proteins, free amino acids, 
 amino sugars and other complex, generally unidentified compounds. 
 These compounds decompose at various rates ranging from fresh crop 
 residues that are subject to fairly rapid decomposition to lignins 
 which are very resistant to decomposition. 
 
 Mineralization is the process by which organic nitrogen is converted 
 to inorganic or mineral nitrogen compounds. Mineralization, through 
 the effect of various types of micro-organisms essentially takes 
 place in three step-by-step reactions: aminization, ammonif ication 
 and nitrification. These steps are represented schematically by the 
 following formula : 
 
 Aminization: Proteins — ► R-NH2 -t- CO2 + energy -+ other products 
 Ammonif ication: R-NH2 -<- HO H ^ NH4+-1- R -»- OH -^ energy 
 Nitrification: 2NH4 + 3O2 ^ 2NO2 ■*■ 2H2O + 4H + 
 2NO2 +02^ 2NO3 
 
 These reactions will go to completion only if several environmental 
 factors are favorable. Generally, these are 1) adequate supply of 
 ammonium ion, 2) adequate population of nitrifying organisms, 
 3) adequate aeration, 4) favorable soil moisture and temperature 
 conditions. The most favorable conditions for these reactions to 
 take place occur in the plow zone of moist soils after they have 
 been disturbed and aerated by cultivation. 
 
 Nitrates and ammonium are the main mineral nitrogen forms that exist 
 in the soil. The nature of NH4 permits adsorption and retention 
 by soil collodial material, therefore, it is generally not subject 
 to removal by leaching waters. Nitrate nitrogen is very mobile in 
 some soils and within limits moves with the soil water, therefore, 
 under conditions of excess irrigation or rainfall, nitrates can be 
 leached through the soils and will be concentrated in the subsoils 
 or the groundwater. 
 
 As there are processes for the accumulation of nitrogen in the soils, 
 there are processes by which it is lost other than by leaching and 
 crop removal. These losses occur when nitrogen gas, nitrous oxide 
 or ammonia are released because of certain biological and chemical 
 reactions taking place on or in the soils. The three primary 
 processes which cause these losses are: 
 
 1, Denitrif ication: The biochemical reduction of nitrates 
 under anaerobic conditions. 
 
 2. Chemical reactions involving nitrates under aerobic 
 conditions. 
 
 (20) 
 
3. Volatilization of ammonia gas from the surface of 
 alkaline soils. 
 
 Although there are conflicting data and opinions, most soil scien- 
 tists believe that an appreciable amount of applied nitrogen is 
 lost in gaseous forms to the atmosphere. Biological denitrifica- 
 tion is considered to be one of the more important processes 
 accounting for these losses and nitrogen, N^ , is believed to be 
 the principle gas produced. Where nitrate occurs in zones of poor 
 aeration, significant quantities of nitrogen can be lost by this 
 process. Nitrogen balance studies have shown mineral nitrogen 
 losses of about 20 percent with cropping and 10 percent with fallow 
 (16). 
 
 Normally, ammonia losses resulting from surface volatilization can 
 be prevented or reduced greatly by placing the nitrogen fertilizers 
 several inches below the soil surface. 
 
 Nitrogen Contributions 
 
 The major sources of nitrogen, not considering that native to the 
 soils are : 
 
 Fertilizers 
 
 This is an intensively farmed area and to gain maximum yields large 
 amounts of nitrogenous fertilizers are applied. These fertilizers 
 may be classified broadly as either "natural organic" or "chemical.' 
 Today in terms of tonnage consumed, chemical sources of .nitrogen 
 are by far the most important of the fertilizer nitrogen compounds. 
 Most of the chemical fertilizers applied in this area are ammonia 
 derivatives. Information supplied by local dealers indicates that 
 the amounts of the various types of fertilizers sold in the area 
 were distributed approximately as follows: 
 
 Percent 
 
 Ammonia (all forms) 63 
 
 Ammonium Sulfate 16 
 
 Urea 9 
 
 Urea - ammonium compounds 6 
 
 Other solids (ammonium nitrate, calcium 
 
 nitrate, ammonium phosphate) 5 
 
 The amount of nitrogen applied to the study area in 1958 based on 
 the acreage and the estimated application rate of each crop is 
 presented in Table 1. The total nitrogen applied was calculated 
 to be 20,210 tons placed on 569,160 gross acres of which 555,875 
 acres were cropped. This is equivalent to an average application 
 of 73 pounds per productive acre or 54 pounds per gross acre. 
 
 Irrigation Water 
 
 Irrigation water is supplied to the area from deep wells, the 
 
 (21) 
 
TABLE 1 
 
 Nitrogen Contributed by Fertilizer 1968 
 San Luis Service Area 
 
 Crop 
 
 Cotton 
 
 Cotton (50% ground cover) 
 
 Cotton (70% ground cover) 
 
 Grain 
 
 Sugar Beets 
 
 Sorghum 
 
 Saff lower 
 
 Field Corn 
 
 Misc. Field Crop 
 
 Dry Beans 
 
 Tomatoes 
 
 Melons 
 
 Lettuce 
 
 Carrots 
 
 Misc. Truck Crops 
 
 Alfalfa & Pasture 
 
 Alfalfa Seed 
 
 Rice 
 
 Deciduous Fruits & Nuts 
 
 Vineyards 
 
 Total Cropped Area 
 Non Cropped Area 
 Total 
 
 Acres lbs, 
 
 51,119 
 
 110 
 
 48,975 
 
 55 
 
 44,300 
 
 77 
 
 230,832 
 
 70 
 
 2,661 
 
 100 
 
 3,094 
 
 130 
 
 53,440 
 
 80 
 
 749 
 
 200 
 
 492 
 
 100 
 
 439 
 
 
 
 23,890 
 
 100 
 
 26,314 
 
 100 
 
 662 
 
 150 
 
 124 
 
 120 
 
 1,063 
 
 150 
 
 6,348 
 
 40 
 
 55,581 
 
 20 
 
 825 
 
 80 
 
 5,348 
 
 120 
 
 620 
 
 45 
 
 556,875 
 
 73 
 
 112,28 5 
 
 
 
 669,160 
 
 64 
 
 Nitrogen Applied 
 per Acre Total Tons 
 
 2,810 
 
 1,350 
 
 1,70C 
 
 8,080 
 
 130 
 
 200 
 
 2,140 
 
 70 
 
 20 
 
 1,200 
 
 1,320 
 
 50 
 
 10 
 
 80 
 
 130 
 
 560 
 
 30 
 
 320 
 
 10 
 
 20,210 
 
 
 
 20,210 
 
 San Luis Canal and the Delta-Mendota Canal. The relative amounts 
 of nitrogen contributed from these sources are listed in the follow- 
 ing paragraphs. 
 
 Wells 
 
 Prior to the importation of surface water from the San Luis Project, 
 this area was irrigated entirely by water pumped from deep wells. 
 In the future there will continue to be pumping from wells although 
 at a reduced rate. In 1968 it was estimated that about 900,450 acre- 
 feet were supplied from wells. Under ultimate development and a 
 complete distribution syste, it is estimated that 460,000 acre-feet, 
 the annual "safe yield", will be pumped each year. 
 
 The nitrate content, the only significant nitrogen form present, 
 was determined for water samples taken from 360 representative 
 irrigation wells which pump from depths of 200 to 3,000 feet. The 
 nitrate -N concentration of these wells ranged from to 10 mg/1 
 
 (22) 
 
 I 
 
with the average about 0.5 mg/l. In 1968 the nitrogen contributed 
 by well water totaled 510 tons or 1.8 pounds per acre. If it is 
 assumed that the nitrogen content will not vary significantly in the 
 future, the 450,000 acre-feet that will be pumped under ultimate 
 conditions will contribute 310 tons of nitrogen annually. This 
 quantity is equivalent to about 0.9 pounds per acre. 
 
 A summary of the contribution of nitrogen from the wells is included 
 in Table 2. 
 
 TABLE 2 
 
 Total Nitrogen Contributions from Irrigation Water 
 
 1958 and Ultimate 
 
 San Luis Service Area 
 
 Source 
 
 
 Deliveries 
 
 1958 Ultimate 
 AF AF 
 
 mg/1 
 
 Total Ni 
 
 1968 
 Ibs/ac cons 
 
 trogen 
 
 Ultimat 
 mg/1 Ibs/ac 
 
 tons 
 
 Wells 
 
 Canals 
 
 Totals 
 
 1 
 
 900,450 
 
 195,600 
 
 ,095,050 
 
 460,000 
 1,240,000 
 1,700,000 
 
 0.5 
 0.8 
 
 1.8 610 
 0.6 210 
 2.4 820 
 
 0.5 0.9 
 
 0.8 4.0 
 
 4.9 
 
 310 
 1,3 50 
 1,660 
 
 Canal Water 
 
 
 
 
 
 
 The surface deliveries to the area are primarily from the San Luis 
 Canal with smaller amounts from the Delta-Mendota Canal. The source 
 of water for both canals is the San Joaquin-Sacramento River Delta 
 near Tracy. There will be no significant differences in the nitro- 
 gen content between the two canals, therefore, the deliveries from 
 both are combined for this study. During the first two years of 
 operation of the San Luis Canal, the weighted average of total N in 
 the water was 0.8 mg/1. This includes about 0.4 mg/1 of NO3-N, 0.1 
 mg/1 of NH3-N and 0.3 mg/1 of organic N. At this rate the total 
 nitrogen contribution to the area in 1958 by the 19 5,500 acre-feet 
 of canal diversions was 210 tons or an average of 0.5 pounds per 
 acre. Under ultimate development, about 1,240,000 acre-feet will 
 be delivered annually to the service area from the two canals. 
 This quantity of water, assuming the N content remains constant, will 
 add 1,3 50 tons or 4.0 pounds per acre of nitrogen to the area. The 
 total quantity of N contributed by the irrigation water was 2.4 
 pounds per acre in 1968 and will rise to 4.9 pounds per acre under 
 ultimate development. A summary of the contribution of nitrogen by 
 canal diversions and groundwater pumpage is in Table 2. 
 
 Stream and Flood Flow 
 
 The several intermittent streams that flow into the area are a 
 source of nitrogen. These streams originate in the Coast Range 
 Mountains to the west and flow for only short periods in the winter 
 
 (23) 
 
stream 
 
 Quantity 
 
 N Content 
 
 Total N 
 
 
 AF 
 
 PPM 
 
 tons 
 
 Los Gatos Group 
 
 2,000 
 
 0.5 
 
 1.3 
 
 Cantua Group 
 
 9,000 
 
 0.6 . 
 
 7.3 
 
 Panoche Group 
 
 14,000 
 
 0.5 
 
 9.5 
 
 Little Panoche 
 
 Group 7,000 
 32,000 
 
 0.5 
 
 4.7 
 
 
 22.8 
 
 and spring following the more intense storms over their watersheds. 
 For planning purposes these streams are placed into four groups 
 which include a major stream and several lesser ones. They are, 
 from north to south, the Little Panoche group, Panoche group, 
 Cantua group and the Los Gatos group. The Ground water Section of 
 the Geologry Branch of the Bureau of Reclamation at Sacramento has 
 calculated from the historical records the average flow contribution 
 of each of these groups. The nitrogen content of the streams of 
 the various groups was based on tests made by U.S.B.R. Fresno Field 
 Division personnel. Table 3 is a summary of these values. 
 
 TABLE 3 
 
 Average Annual Nitrogen Contribution by Local Streams 
 San Luis Service Area 
 
 Ibs/ac 
 
 "TW 
 
 The 22.8 tons calculated for the area of 669,160 acres would be 
 equivalent to less than 0.1 pounds per acre. Although a sizeable 
 amount it is not significant in the total budget. 
 
 Legtmiinous Plants 
 
 For many centuries the use of leguminous crops has been one of the 
 principal means of supplying nitrogen to the soil. In this process 
 various strains of the Rhizobial bacteria growing in a symbiotic 
 relationship with a host plant will fix atmospheric nitrogen in 
 nodules on the roots of the plant. The amount of nitrogen fixed by 
 this process will vary with the type of crop, soil, climate and 
 moisture conditions. 
 
 Historically, leguminous native plants were the main contributors 
 of this type of nitrogen in the area, however, with the intensive 
 cultivation of the area most of the native plants have been removed. 
 In their place, a number of cultivated legumes are grown. The 
 largest acreage by far of legximinous crops is in alfalfa. Beans, 
 the only other legume, are a relatively small acreage. Alfalfa 
 seed, which fixes less nitrogen than alfalfa hay, is the major 
 alfalfa crop grown in the area. The weighted average of the nitrogen 
 fixation in this area by the alfalfa seed and hay crops is estimated 
 at 145 pounds per acre. There were 61,929 acres of alfalfa seed and 
 hay grown in the area in 1968. This acreage at the estimated rate 
 of fixation would contribute about 4,500 tons of nitrogen to the area. 
 
 (24) 
 
The estimated amount of fixation by beans is about 40 pounds per 
 acre. At this rate, the 439 acres of beans grown would contribute 
 about 10 tons of nitrogen. 
 
 The total quantity of nitrogen fixed by leguminous crops in 1968 
 was about 4,510 tons or 13.7 pounds per gross acre. A summary of 
 the nitrogen contribution by legumes is in Table 4. 
 
 
 
 
 TABLE 
 
 _4 
 
 
 
 Nitrogen 
 
 Contri 
 
 but 
 San 
 
 ion from Legiminous Plants 
 Luis Service Area 
 
 - 1968 
 
 Crop 
 Alfalfa 
 
 Acres 
 61,929 
 
 
 N/Acre 
 lbs 
 194 
 
 
 Total N 
 
 tons 
 4,500 
 
 Ave/Acre (1) 
 lbs 
 13.6 
 
 Beans 
 
 439 
 
 
 40 
 
 
 10 
 
 0.1 
 
 4,510 
 (1) Based on gross acreage of service area 
 
 13.7 
 
 Rainfall 
 
 Nitrogen compounds are present in the atmosphere and are returned 
 to the earth in rainfall. This nitrogen is mainly in the form of 
 ammonia and nitrate with lesser amounts of nitrite, nitrous oxide, 
 and organic forms. The presence of NOt has been attributed to its 
 formation during atmospheric electrical discharges but recent studies 
 suggest that only about 10 to 20 percent of the NO3 in rainfall is 
 from this source (8). The remainder is thought to come from indust- 
 rial waste gases or from nitrogenous gases that escape the soil. 
 
 The amount of nitrogen that is returned to the soil in this manner 
 has been studied by a number of authors (7) (8). The estimated 
 concentrations for this area are approximately 0.1 part per million 
 of NO7-N. The average rainfall is about 6.6 inches per year. 
 
 The nitrogen contributed to the soil by the rainfall each year would 
 total 100 tons or 0.3 pounds per acre. 
 
 Livestock 
 
 The livestock population of the area in 1968 was estimated at 37,000 
 beef cattle and 135,000 sheep. The cattle were concentrated in three 
 feed lots. The sheep graze in the area for about half the year during 
 the fall and winter, and then are moved to higher Icinds outside the 
 district. There are no appreciable numbers of other types of live- 
 stock within the area. 
 
 (25) 
 
The amount of waste nitrogen contributed by these animals was based 
 on the calculated daily waste excreted by the animals times the 
 number of days fed or pastured in the area. The beef cattle con- 
 tributed a total of 1,890 tons or based on the gross area, 5.7 
 pounds per acre. Although some of the manure is removed from the 
 feed lots and spread on other lands, much N will be concentrated 
 in the soils below and immediately adjacent to the feed lots. 
 The sheep are grazed over a relatively large acreage, as a result 
 their waste nitrogen will be distributed fairly evenly over the 
 area. The total N contributed by the sheep was 910 tons or 2.7 
 pounds per gross acre. The total for all the animals would be 2,800 
 tons or 8.4 pounds per acre. A summary of the contribution by live- 
 stock is in Table 5. 
 
 TABLE 5 
 
 Nitrogen Contribution for Animals - 1958 
 San Luis Service Area 
 
 Animal 
 Beef Cattle 
 Sheep 
 
 Number 
 
 37,000 
 135,300 
 
 (1) 
 
 Nitrogen 
 Ibs/day/animal 
 
 Tons/yr 
 
 Ibs/AC 
 
 .as'^"' 
 
 1,890 
 
 5.7 
 
 .09<^' 
 
 910 
 2,800 
 
 2.7 
 8.4 
 
 (1) 150 days/year pastured in area 
 
 (2) 9 lbs dry manure/day |3 3.10% N 
 
 (3) 1.64 lbs dry manure/day (a 5.4% N 
 
 Municipal and Industrial 
 
 This is primarily a rural area of relatively large farm operations. 
 Other than the Lemoore Naval Air Station, the largest single 
 employer in the district, the population is concentrated in a few 
 small towns and several large farm labor camps. The industries 
 are limited to a few agriculture related enterprises such as farm 
 equipment dealers, machine shops, trucking firms, and fruit and 
 vegetable packing plants. 
 
 The 1960 population as estimated from data supplied by Fresno 
 County Planning Office was 16,450 people and the 1968 population 
 17,400. These population figures include the Lemoore Naval Air Base 
 and the towns of Mendota, Huron and Five Points. In the work by 
 R. C. Loeher (13) it is estimated that the nitrogen contribution 
 of domestic waste is between 8-12 pounds per year per capita. If 
 it is assumed that the average would be 10 pounds per capita the 
 
 (26) 
 
17,400 people would contribute 87 tons or about .3 pounds per gross 
 acre. This nitrogen is not spread uniformly over the area but it 
 is concentrated in relatively small areas at the disposal plants 
 of the towns and camps. The overall area covered by these popu- 
 lation centers is probably not greater than 3,300 acres. If the 
 total quantity of nitrogen waste is prorated to this acreage, the 
 average would be about 53 pounds per acre. It is obvious from this 
 that adjacent to the sewage disposal areas there can be relatively 
 high concentrations of nitrates introduced into the soils although 
 the overall total is small. 
 
 Nitrogen Losses 
 
 The main causes of the loss of nitrogen from the soil are removal 
 by crops, volatilization of nitrogen fertilizers and denitrification. 
 
 Removal by Crops 
 
 The major medium of nitrogen removal is through its uptake by the 
 crop and its ultimate removal by harvesting. The quantity of ni- 
 trogen removed by this means was determined from the number of acres 
 of each crop as measured by the 1968 crop survey, the estimated 
 crop yields and the nitrogen content of the crop material. These 
 latter values were determined in part from Morrison's "Feed and 
 Feeding" (14). The amount removed was broken down into the materials 
 which are removed from the area and the plant residue that is nor- 
 mally returned to the soil. At least a part of the nitrogen in 
 this latter material will again become available for plant growth 
 through mineralization Although the amount of nitrogen removed 
 by the various crops will vary, depending upon such factors as yield 
 levels, nutrient supply in the soil, fertilizer applied and manage- 
 ment practices, representative nitrogen uptake data for the various 
 crops in this area for 1968 are presented in Table 6. 
 
 The amount removed ranged from about 322 pounds in alfalfa hay to 
 37 pounds in beans. The average of all the crops is 89 pounds per 
 acre. This relatively low rate is due primarily to the high percent- 
 age of the area planted to barley which has a relatively low utili- 
 zation rate. 
 
 Volatilization of Ammonia Fertilizers 
 
 Ammonium salts when applied to an alkaline soil will react to form 
 ammonia gas which if unconfined will be released to the air. The 
 rate of this reaction will vary greatly with soil condition, pH, 
 temperature, moisture content and depth of placement. Studies (4) 
 (6) have shown that when ammonium salts or ammonia gas are placed 
 on the soil surface more than 40 percent of the material can be 
 lost to volatilization, however, if it is placed several inches be- 
 low the ground surface essentially none of the ammonia is lost. In 
 this area although there are small amounts of the fertilizer applied 
 
 (27) 
 
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by airplanes, in the water or by broadcast methods the great bulk 
 of it is drilled to several inches below the soil surface. Under 
 these conditions it is estimated that not more than 5 percent of 
 the fertilizer applied is lost. 
 
 Approximately 95 percent of 19,200 tons of the fertilizer applied 
 to the area in 1968 was in the ammonia or urea form which is subject 
 to volatilization. If 5 percent of this amount is lost, it would 
 be equivalent to 960 tons or about 3 pounds per gross acre. 
 
 Denitrification 
 
 Studies have shown that there are losses of nitrogen from soil by 
 denitrification, the biochemical reduction of nitrates under anaer- 
 obic conditions (17)(18). In calcareous soils such as are present 
 in this area the loss will primarily be in the form of nitrogen gas. 
 Water logging with its resulting exclusion of oxygen induces deni- 
 trification, therefore, in the areas of high water table and in the 
 presence of organic carbon there will be significant losses through 
 this process. Lysimeter studies indicate that under optimum con- 
 ditions almost 100 percent of the nitrate -N present can be lost 
 through denitrification. The specific quantity of nitrogen lost in 
 the field by this method in this area has been impossible to measure 
 therefore any attempt at this time to put a numerical value on 
 denitrification losses would be meaningless. 
 
 Nitrogen Budget Summary 
 
 A summary of the quantity of nitrogen contributed and removed from 
 the soil by the various processes is in Table 7. This summary in- 
 dicates annual nitrogen losses, without attributing any value to 
 denitrification, are slightly greater than the total contributions. 
 Considering the accuracy of the measurements, for all practical pur- 
 poses there are probably no significant differences between the two. 
 
 The total nitrogen removed by the plant from the soil system, in- 
 cluding that portion in the plant material that may be returned to 
 the soil, was included as a nitrogen loss item. Although some of 
 this is returned to the soil, it is in an organic form which must 
 be mineralized before it can be utilized by the plant or leached 
 by the percolating waters. 
 
 These values are based on an even distribution of nitrogen over the 
 entire acreage, however, in fact, this would not be true. Also the 
 native nitrates and the organic nitrogen that is mineralized are not 
 included in the balance study. Although the quantity of nitrogen moved 
 through the soils to the drains will be roughly equivalent to the con- 
 tribution from native nitrates and the mineralized organic nitrogen, 
 under actual field conditions these natural nitrogen sources will 
 replace some of the other types in the plant's nitrogen use. There- 
 fore, a part of the nitrogen that is leached to the drain will come 
 
 (29) 
 
TABLE 7 
 
 Nitrogen Budget 1968 - San Luis Ser vice Area 
 
 Sources Nitrogen 
 
 Nitrogen Contributions Ibs./ac. 
 
 Fertilizer 64.0 
 
 Irrigation Water 2.4 
 
 Stream Flow 0.1 
 
 Rainfall 0.3 
 
 Legximinous Plants 13.7 
 
 Livestock 8.4 
 
 Municipal & Industrial Waste 0.3 
 
 89.2 
 
 Losses 
 
 Crop Harvest 89.0 
 
 Volatilization 3.0 
 
 Denitrification 
 
 92.0 
 
 from the applied sources, principally from the fertilizer. The 
 amount of fertilizer leached will depend upon many factors, includ- 
 ing the type and amount of fertilizer, when and how applied, the 
 crop and root pattern, method and amount of irrigation, and the soil 
 type. 
 
 Transect Study 
 
 The objectives of the transect study were to determine the quantities 
 and the distribution of the various nitrogen forms, both with depth 
 and areawise and to determine the deviations in soils of similar 
 type within small areas. 
 
 Nitrogen in the Soil 
 
 The average content of NO3-N, NH3-N and organic N in parts per mil- 
 lion and the pounds per acre foot for each foot increment were deter- 
 mined from 1:1 soil-water extracts. The quantities of the first 
 five foot increments of each site are listed in Table 8. 
 
 The data indicate that the total nitrogen in the top five feet of 
 soil at the various sites ranged from a low of 4321 pounds per acre 
 at site 7, a Levis soil, to a high of 8849 pounds per acre at site 
 12, a Panoche soil. Of this quantity, the greatest portion by far 
 was the organic nitrogen. The amount in this form ranged from 4140 
 
 (30) 
 
 I 
 
TABLE 8 
 
 Quantities of Various Forms of Nitrogen at Transect Sites 
 as Determined from 1:1 Soil-Water Extracts 
 
 Depth 
 
 NO 
 
 5-N 
 
 NF 
 
 I3-N 
 
 Org 
 
 anic N 
 
 Total N 
 
 Ft 
 
 PPM 
 
 Ibs/ftp 
 
 PPM 
 
 Ibs/AF 
 
 PPM 
 
 Ibs/AF 
 
 Ibs/AF 
 
 
 
 Site #1 
 
 T19S 
 
 R18E S 23 
 
 - Oxalis Soil 
 
 
 0-1 
 
 3.4 
 
 12 
 
 6 
 
 20 
 
 520 
 
 1872 
 
 1904 
 
 1-2 
 
 18.5 
 
 67 
 
 3 
 
 12 
 
 405 
 
 1458 
 
 1537 
 
 2-3 
 
 7.9 
 
 28 
 
 3 
 
 10 
 
 306 
 
 1102 
 
 1140 
 
 3-4 
 
 4.3 
 
 15 
 
 3 
 
 12 
 
 213 
 
 757 
 
 794 
 
 4-5 
 
 12.6 
 
 45 
 
 4 
 
 15 
 
 259 
 
 932 
 
 992 
 
 
 
 157 
 
 
 69 
 
 
 6131 
 
 6357 
 
 Site #2 T19 R19 S27 - Lethent Soil 
 
 0-1 
 
 1.6 
 
 6 
 
 5 
 
 18 
 
 533 
 
 2279 
 
 2303 
 
 1-2 
 
 4.1 
 
 15 
 
 2 
 
 7 
 
 282 
 
 1015 
 
 1037 
 
 2-3 
 
 1.4 
 
 5 
 
 2 
 
 7 
 
 229 
 
 824 
 
 836 
 
 3-4 
 
 1.4 
 
 5 
 
 1 
 
 4 
 
 222 
 
 799 
 
 804 
 
 4-5 
 
 1.4 
 
 5 
 
 2 
 
 7 
 
 222 
 
 799 
 
 807 
 
 
 
 36 
 
 
 43 
 
 
 5716 
 
 5787 
 
 Site #3 T19 R17 S20 - Panoche Soil 
 
 0-1 
 
 3.2 
 
 12 
 
 5 
 
 22 
 
 3 50 
 
 1260 
 
 1294 
 
 1-2 
 
 2.3 
 
 8 
 
 5 
 
 18 
 
 380 
 
 1358 
 
 1394 
 
 2-3 
 
 0.9 
 
 3 
 
 4 
 
 14 
 
 224 
 
 805 
 
 823 
 
 3-4 
 
 1.1 
 
 4 
 
 3 
 
 11 
 
 273 
 
 983 
 
 998 
 
 4-5 
 
 1.4 
 
 5 
 
 3 
 
 11 
 
 280 
 
 1008 
 
 1024 
 
 
 
 32 
 
 
 75 
 
 
 5425 
 
 5533 
 
 Site #4 T19 R15 S15 - Panoche Soil 
 
 0-1 
 
 11.5 
 
 41 
 
 4 
 
 14 
 
 491 
 
 1758 
 
 1823 
 
 1-2 
 
 12.5 
 
 45 
 
 3 
 
 11 
 
 4 59 
 
 1552 
 
 1708 
 
 2-3 
 
 12.9 
 
 45 
 
 2 
 
 7 
 
 315 
 
 1134 
 
 1187 
 
 3-4 
 
 8.8 
 
 32 
 
 3 
 
 11 
 
 278 
 
 1001 
 
 1044 
 
 4-5 
 
 9.7 
 
 35 
 
 3 
 
 11 
 
 245 
 
 886 
 
 932 
 
 
 
 199 
 
 
 54 
 
 
 6441 
 
 6594 
 
 (31) 
 
TABLE 8 (Cont.) 
 
 Depth 
 
 NO 
 
 3-N 
 
 
 NH3 
 
 -N 
 
 Organic N 
 
 Total N 
 
 Ft 
 
 PPM 
 
 lbs 
 
 /AF 
 
 PPM 
 
 Ibs/AF 
 
 PPM 
 
 Ibs/AF 
 
 Ibs/AF 
 
 
 
 Site 
 
 #5 
 
 T17 R16 
 
 S22 - 
 
 Oxalis 
 
 Soil 
 
 
 0-1 
 
 1.4 
 
 5 
 
 
 6 
 
 22 
 
 606 
 
 2182 
 
 2209 
 
 1-2 
 
 1.1 
 
 4 
 
 
 5 
 
 18 
 
 382 
 
 1375 
 
 1397 
 
 2-3 
 
 1.8 
 
 6 
 
 
 5 
 
 18 
 
 287 
 
 1033 
 
 1057 
 
 3-4 
 
 2.5 
 
 9 
 
 
 4 
 
 14 
 
 216 
 
 778 
 
 801 
 
 4-5 
 
 5.2 
 
 19 
 43 
 
 
 4 
 
 14 
 86 
 
 250 
 
 900 
 6268 
 
 933 
 6397 
 
 
 
 Site 
 
 #6 
 
 T16 R16 
 
 S22 - 
 
 Lethent Soil 
 
 
 0-1 
 
 19.1 
 
 69 
 
 
 5 
 
 18 
 
 647 
 
 2329 
 
 2416 
 
 1-2 
 
 3.2 
 
 12 
 
 
 5 
 
 11 
 
 456 
 
 1642 
 
 1665 
 
 2-3 
 
 1.4 
 
 5 
 
 
 3 
 
 11 
 
 388 
 
 1397 
 
 1413 
 
 3-4 
 
 1.6 
 
 6 
 
 
 2 
 
 7 
 
 368 
 
 1325 
 
 1338 
 
 4-5 
 
 2.5 
 
 9 
 101 
 
 
 2 
 
 7 
 54 
 
 295 
 
 1062 
 7755 
 
 1078 
 7910 
 
 
 
 Site 
 
 #7 
 
 T15 R15 
 
 S26 - 
 
 Levis Soil 
 
 
 0-1 
 
 14.4 
 
 52 
 
 
 5 
 
 18 
 
 442 
 
 1591 
 
 1661 
 
 1-2 
 
 8.4 
 
 30 
 
 
 3 
 
 11 
 
 258 
 
 929 
 
 970 
 
 2-3 
 
 6.8 
 
 24 
 
 
 3 
 
 11 
 
 175 
 
 630 
 
 665 
 
 3-4 
 
 3.6 
 
 13 
 
 
 2 
 
 7 
 
 147 
 
 529 
 
 549 
 
 4-5 
 
 2.3 
 
 8 
 127 
 
 
 2 
 
 7 
 54 
 
 128 
 
 461 
 4140 
 
 476 
 4321 
 
 
 
 Site 
 
 #8 
 
 T15 R14 
 
 S27 - 
 
 Oxalis 
 
 Soil 
 
 
 0-1 
 
 7.7 
 
 28 
 
 
 6 
 
 22 
 
 505 
 
 1818 
 
 1868 
 
 1-2 
 
 22.1 
 
 80 
 
 
 3 
 
 11 
 
 309 
 
 1112 
 
 1203 
 
 2-3 
 
 48.1 
 
 173 
 
 
 2 
 
 7 
 
 212 
 
 763 
 
 943 
 
 3-4 
 
 53.9 
 
 194 
 
 
 2 
 
 7 
 
 210 
 
 756 
 
 957 
 
 4-5 
 
 174.0 
 
 626 
 
 1101 
 
 
 2 
 
 7 
 
 54 
 
 202 
 
 727 
 5176 
 
 1360 
 6331 
 
 
 
 Site 
 
 #9 
 
 T15 R13 
 
 S26 - 
 
 Panoche Soil 
 
 
 0-1 
 
 6.6 
 
 24 
 
 
 4 
 
 14 
 
 444 
 
 1598 
 
 1636 
 
 1-2 
 
 2.7 
 
 10 
 
 
 3 
 
 11 
 
 312 
 
 1123 
 
 1144 
 
 2-3 
 
 11.1 
 
 40 
 
 
 3 
 
 11 
 
 214 
 
 770 
 
 821 
 
 3-4 
 
 14.2 
 
 51 
 
 
 4 
 
 14 
 
 160 
 
 576 
 
 641 
 
 4-5 
 
 22.6 
 
 81 
 206 
 
 
 2 
 
 7 
 57 
 
 149 
 
 535 
 4603 
 
 624 
 4866 
 
 (32) 
 
TABLE 8 (Cont.) 
 
 Depth 
 
 NO3-N 
 
 
 NH3-N 
 
 Organic N 
 
 Total N 
 
 Ft 
 
 PPM 
 
 Ibs/AF 
 
 PPM Ibs/AF 
 
 PPM Ibs/AF 
 
 Ibs/AF 
 
 
 
 Site 
 
 #10 
 
 T14 R12 S26 - 
 
 Lost Hills Soil 
 
 
 0-1 
 
 31,2 
 
 112 
 
 
 3 11 
 
 434 1562 
 
 158 5 
 
 1-2 
 
 35.2 
 
 127 
 
 
 2 7 
 
 247 889 
 
 1023 
 
 2-3 
 
 42.7 
 
 154 
 
 
 2 7 
 
 182 655 
 
 816 
 
 3-4 
 
 52.6 
 
 189 
 
 
 1 4 
 
 175 630 
 
 823 
 
 4-5 
 
 55.3 
 
 199 
 
 
 1 4 
 
 163 587 
 
 790 
 
 
 
 781 
 
 
 33 
 
 4323 
 
 5137 
 
 Site #11 T14 R12 S13 - Panoche Soil 
 
 0-1 
 
 43.1 
 
 155 
 
 3 
 
 11 
 
 401 
 
 1444 
 
 1610 
 
 1-2 
 
 21.9 
 
 79 
 
 2 
 
 7 
 
 271 
 
 976 
 
 1052 
 
 2-3 
 
 9.5 
 
 34 
 
 1 
 
 4 
 
 168 
 
 605 
 
 543 
 
 3-4 
 
 8.1 
 
 29 
 
 1 
 
 4 
 
 150 
 
 540 
 
 573 
 
 4-5 
 
 6.3 
 
 23 
 
 1 
 
 4 
 
 149 
 
 535 
 
 563 
 
 320 
 
 30 
 
 4101 
 
 4451 
 
 Site 12 T13 R13 S23 - Panoche Soil 
 
 0-1 
 
 14.2 
 
 51 
 
 4 
 
 14 
 
 660 
 
 2376 
 
 2441 
 
 1-2 
 
 3.8 
 
 14 
 
 2 
 
 7 
 
 521 
 
 1876 
 
 1897 
 
 2-3 
 
 3.2 
 
 12 
 
 1 
 
 4 
 
 481 
 
 1732 
 
 1748 
 
 3-4 
 
 8.1 
 
 29 
 
 1 
 
 4 
 
 398 
 
 1433 
 
 1456 
 
 4-5 
 
 11.1 
 
 40 
 
 1 
 
 4 
 
 348 
 
 12 53 
 
 1297 
 
 
 
 146 
 
 
 33 
 
 
 8670 
 
 8849 
 
 
 
 Site #13 
 
 T12 R13 
 
 S25 
 
 - Oxalis 
 
 Soil 
 
 
 0-1 
 
 17.6 
 
 63 
 
 7 
 
 25 
 
 687 
 
 2473 
 
 2561 
 
 1-2 
 
 2.9 
 
 10 
 
 4 
 
 14 
 
 427 
 
 1537 
 
 1561 
 
 2-3 
 
 5.9 
 
 21 
 
 2 
 
 7 
 
 328 
 
 1181 
 
 1209 
 
 3-4 
 
 0.9 
 
 3 
 
 4 
 
 14 
 
 279 
 
 1004 
 
 1021 
 
 4-5 
 
 0.9 
 
 3 
 
 4 
 
 14 
 
 250 
 
 900 
 
 917 
 
 
 
 100 
 
 
 74 
 
 
 709 5 
 
 7269 
 
 to 8570 pounds per acre. Nitrate -N was the next largest constit- 
 uent with a range of 28 to 1101 pounds per acre. The amount 
 of NH3 in the soil was low but rather consistent with a range of 
 30 to 85 pounds per acre. 
 
 Soil organic matter is the source of the organic nitrogen which 
 comprised more than 98 percent of the total nitrogen in some of the 
 sites. Soil organic matter is an ill defined term used to cover 
 
 (33) 
 
organic materials in all stages of decomposition from humus, which 
 is relatively resistant to further decomposition, to fresh crop 
 residues that are subject to fairly rapid decomposition. Studies 
 have shown that this organic nitrogen exists about 5-10 percent 
 in the form of nucleic acids; about 30 to 40 percent in the form of 
 proteins or its derivatives and about 10 to 15 percent as amino 
 sugar. Most of the remaining nitrogen has not been characterized. 
 Although quite refractory some of this nitrogen can be converted by 
 bacterial action to NHt and/or NO3. 
 
 Although there were several exceptions, most often in the first five 
 feet of soil, the nitrate nitrogen and organic nitrogen concentrations 
 were greatest in the surface foot. This is probably due to the higher 
 rate of mineralization in the better aerated surface soil and residual 
 nitrates from fertilizer, the absorption of the NH3 fertilizer by 
 the clay complex, and the result of the organic matter incorporated 
 into the surface soils. 
 
 The distribution of the various nitrogen forms did not show any 
 distinct pattern in relation to soil series, physiographic position 
 or geomorphic area. The minimum, maximum and average NO3-N and organic 
 N contents for several soil types and physiographic positions are 
 listed in Table 9. The NO3-N concentration in the seven basin rim 
 soils ranged from a minimum of one to a maximum of 100 with an average 
 of 14 parts per million. These figures include one site which had 
 an extremely high concentration. If this site is excluded the average 
 NO3-N would be only five parts per million. 
 
 The NO3-N concentration of five recent alluvial soils ranged from a 
 minimum of 2 to a maximum of 35 with an average of about 11 parts 
 
 TABLE 9 
 
 Minimum, Maximum and Average NO3-N and Organic N 
 
 Concentrations at the Various Sites by Soil Type, 0-5 Feet 
 
 No . of Minimum Maximum Average 
 
 Sites NO3-N Org.N NO3-N Org.N NO3-N Org.N 
 
 p. p.m. p. p.m. p. p.m. 
 
 Soils 
 
 
 
 
 
 
 
 
 Basin Rim 
 
 
 
 
 
 
 
 
 Oxalis 
 
 4 
 
 2 
 
 250 
 
 100 
 
 412 
 
 20 
 
 349 
 
 Lethent 
 
 2 
 
 1 
 
 297 
 
 5 
 
 511 
 
 4 
 
 379 
 
 Levis 
 
 1 
 
 2 
 
 207 
 
 10 
 
 253 
 
 7 
 
 230 
 
 Recent Alluvial 
 
 
 
 
 
 
 
 
 Panoche 
 
 5 
 
 2 
 
 156 
 
 35 
 
 525 
 
 11 
 
 349 
 
 Old Alluvial 
 
 
 
 
 
 
 
 
 Lost Hills 
 
 1 
 
 22 
 
 225 
 
 94 
 
 248 
 
 42 
 
 240 
 
 (34) 
 
per million. These data would indicate that there is about as 
 much variation within the same soil type as there is between the 
 different soil types and physiographic positions. 
 
 The data as listed in Table 10 also indicates that there are vari- 
 ations in the NO3-N concentrations among the holes located at the 
 saune sites in similar soil material. In some sites there were 
 percentage differences ranging up to 800 percent and actual differences 
 up to 70 parts per million of nitrogen. 
 
 Statistical analyses were made on the variability of the nitrate 
 values at each of the transect sites. These determinations include 
 the averages, standard deviation and the standard error of the 
 mean of the nitrate concentrations from the five borings at each 
 site. The results of these calculations are presented in Table 11. 
 
 The organic nitrogen concentrations, although not exhibiting as 
 great a percentage range as the NO3-N, varied considerably in 
 actual values. Again there was as great or greater variation among 
 the sites of similar soil types as there was among the different 
 soil types and physiographic position. There were also differences 
 among the five holes at the same site , indicating significant 
 variations within small areas. 
 
 The NH3 content of the soil at all of the sites ranged from about 
 1 to 7 parts per million. These values were relatively consistent 
 at all of the sites. There were no appreciable differences between 
 soil type or physiographic position© 
 
 If it is assumed that the concentrations determined for the in- 
 dividual sites are representative of the whole area, the average 
 and total quantity of nitrogen in the top five feet of soil of the 
 study area would be 6,142 pounds per acre of 2,056,660 tons and is 
 segregated as shown in Table 12. 
 
 Nitrogen in the Substrata 
 
 The results of the laboratory analyses for the various forms of 
 nitrogen in the substrata of the transect sites as expressed in 
 parts per million and pounds per acre-foot are summarized in Table 
 13. The substrata as used in this study is defined as those soil 
 horizons between 5 and 40 foot depths. 
 
 Because of the apparent correlation between nitrogen concentration 
 and the fan-interfan position, this was used as a basis to determine 
 the total quantity of nitrogen in the substrata of the area. These 
 values were determined by multiplying the weighted average of the 
 nitrogen concentrations in the 5-40 feet depths of the sites 
 
 (35) 
 
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 m ON On vo m 
 
 n r-l en in CM 
 en en CM i-i m 
 
 O i-l 
 
 00 
 
 ,_! 
 
 r^ 
 
 CM 
 
 r- 
 
 CM -J 
 
 O r^ 
 
 NO 
 
 m r-l 
 
 o 
 
 r>. 
 
 CM 
 
 m 
 
 O 
 
 00 ON 
 
 o <^ 
 
 nO 
 
 CM CM 
 
 en 
 
 en 
 
 en 
 
 ■J- 
 
 CM 
 
 en en 
 
 CM i-l 
 
 <r 
 
 en (^ O m 
 
 o 
 
 ^ m 00 en 
 
 m >J <JN r-l (M 
 
 (36) 
 
TABLE 11 
 
 Summary of NO-r-N in Parts per Million, Standard Deviations and 
 Standard Error of Mean for the Five Holes at Each Nitrate Site 
 
 Depth 
 Ft. 
 
 b c d e Avg . 
 Site #1 T19S R18E S23 - Oxalis Clay 
 
 (1) 
 
 0" 
 
 (2) 
 
 am 
 
 0-1 
 1-2 
 2-3 
 3-4 
 4-5 
 
 10 
 
 2 
 
 2 
 
 2 
 
 2 
 
 67 
 
 4 
 
 10 
 
 10 
 
 2 
 
 26 
 
 2 
 
 6 
 
 3 
 
 2 
 
 12 
 
 3 
 
 2 
 
 2 
 
 3 
 
 19 
 
 15 
 
 11 
 
 4 
 
 15 
 
 4 
 19 
 
 4 
 13 
 
 3 
 
 4 
 
 27 
 
 34 
 
 10 
 
 13 
 
 4 
 
 6 
 
 6 
 
 7 
 
 Site #2 T19 R19 S27 - Lethent Soil 
 
 0-1 
 
 5 
 
 1 
 
 1 
 
 1 
 
 
 
 2 
 
 2 
 
 2 
 
 1-2 
 
 15 
 
 1 
 
 1 
 
 2 
 
 2 
 
 5 
 
 6 
 
 7 
 
 2-3 
 
 2 
 
 1 
 
 1 
 
 2 
 
 1 
 
 1 
 
 1 
 
 1 
 
 3-4 
 
 2 
 
 1 
 
 1 
 
 1 
 
 2 
 
 1 
 
 1 
 
 1 
 
 4-5 
 
 2 
 
 1 
 
 1 
 
 2 
 
 1 
 
 1 
 
 1 
 
 1 
 
 
 
 Site #3 
 
 T19 R17 
 
 S20 - 
 
 ■ Oxalis 
 
 Soil 
 
 
 
 0-1 
 
 3 
 
 3 
 
 4 
 
 4 
 
 3 
 
 3 
 
 1 
 
 1 
 
 1-2 
 
 2 
 
 2 
 
 3 
 
 2 
 
 1 
 
 2 
 
 1 
 
 1 
 
 2-3 
 
 2 
 
 1 
 
 1 
 
 1 
 
 1 
 
 1 
 
 1 
 
 1 
 
 3-4 
 
 4 
 
 1 
 
 1 
 
 1 
 
 1 
 
 1 
 
 1 
 
 2 
 
 4-5 
 
 4 
 
 1 
 
 1 
 
 1 
 
 1 
 
 1 
 
 2 
 
 2 
 
 Site #4 T19 R16 S15 - Panoche Soil 
 
 0-1 
 
 
 12 
 
 
 2 
 
 
 16 
 
 
 16 
 
 13 
 
 
 
 12 
 
 
 6 
 
 7 
 
 1-2 
 
 
 14 
 
 
 2 
 
 
 22 
 
 
 19 
 
 6 
 
 
 
 12 
 
 
 8 
 
 11 
 
 2-3 
 
 
 15 
 
 
 1 
 
 
 19 
 
 
 16 
 
 15 
 
 
 
 13 
 
 
 7 
 
 8 
 
 3-4 
 
 
 9 
 
 
 7 
 
 
 13 
 
 
 12 
 
 4 
 
 
 
 9 
 
 
 4 
 
 5 
 
 4-5 
 
 
 5 
 
 
 9 
 
 
 8 
 
 
 25 
 
 2 
 
 
 
 10 
 
 
 9 
 
 11 
 
 
 
 
 Site 
 
 #5 
 
 T17 
 
 R16 
 
 S22 - 
 
 Oxalis 
 
 So: 
 
 il 
 
 
 
 
 
 0-1 
 
 
 1 
 
 
 2 
 
 
 2 
 
 
 1 
 
 
 
 
 
 1 
 
 
 1 
 
 1 
 
 1-2 
 
 
 12 
 
 
 1 
 
 
 2 
 
 
 1 
 
 1 
 
 
 
 3 
 
 
 6 
 
 7 
 
 2-3 
 
 
 5 
 
 
 1 
 
 
 1 
 
 
 1 
 
 1 
 
 
 
 2 
 
 
 2 
 
 2 
 
 3-4 
 
 
 8 
 
 
 1 
 
 
 1 
 
 
 1 
 
 2 
 
 
 
 2 
 
 
 3 
 
 4 
 
 4-5 
 
 
 11 
 
 
 2 
 
 
 3 
 
 
 4 
 
 5 
 
 
 
 5 
 
 
 3 
 
 4 
 
 (1) 
 
 a 
 
 - Standard 
 
 deviation of 
 
 the 
 
 mean, a 
 
 ill 
 
 values 
 
 -+- 
 
 
 
 (2) 
 
 am 
 
 - Standard 
 
 error s 
 
 3f mean 
 
 I (95 
 
 1 percent ( 
 
 confidence 
 
 interval 
 
 (37) 
 
TABLE 11 (cont.) 
 
 Depth 
 
 
 
 
 
 
 
 
 (1) 
 
 (2) 
 
 Ft. 
 
 a 
 
 b 
 
 c 
 
 
 d 
 
 e 
 
 Avg. 
 
 a 
 
 am 
 
 
 
 Site #6 
 
 T16 
 
 R15 
 
 S22 - 
 
 Lethent Soil 
 
 
 
 0-1 
 
 16 
 
 17 
 
 17 
 
 
 15 
 
 30 
 
 19 
 
 6 
 
 8 
 
 1-2 
 
 2 
 
 5 
 
 4 
 
 
 2 
 
 4 
 
 3 
 
 1 
 
 1 
 
 2-3 
 
 1 
 
 2 
 
 1 
 
 
 2 
 
 1 
 
 1 
 
 1 
 
 1 
 
 3-4 
 
 2 
 
 2 
 
 1 
 
 
 2 
 
 2 
 
 2 
 
 1 
 
 1 
 
 4-5 
 
 3 
 
 2 
 
 2 
 
 
 2 
 
 2 
 
 2 
 
 1 
 
 1 
 
 
 
 Site #7 
 
 T15 
 
 R15 
 
 S26 - 
 
 Levis 
 
 Soil 
 
 
 
 0-1 
 
 16 
 
 20 
 
 7 
 
 
 13 
 
 16 
 
 14 
 
 5 
 
 6 
 
 1-2 
 
 17 
 
 11 
 
 1 
 
 
 5 
 
 8 
 
 8 
 
 5 
 
 8 
 
 2-3 
 
 11 
 
 10 
 
 1 
 
 
 2 
 
 10 
 
 7 
 
 5 
 
 6 
 
 3-4 
 
 5 
 
 6 
 
 1 
 
 
 2 
 
 5 
 
 4 
 
 2 
 
 2 
 
 4-5 
 
 3 
 
 2 
 
 1 
 
 
 2 
 
 3 
 
 2 
 
 1 
 
 1 
 
 Site #8 T15 R14 S27 - Oxalis Soil 
 
 0-1 
 
 14 
 
 6 
 
 4 
 
 10 
 
 5 
 
 8 
 
 4 
 
 5 
 
 1-2 
 
 24 
 
 28 
 
 16 
 
 29 
 
 15 
 
 22 
 
 7 
 
 8 
 
 2-3 
 
 32 
 
 30 
 
 32 
 
 120 
 
 28 
 
 48 
 
 40 
 
 50 
 
 3-4 
 
 29 
 
 48 
 
 67 
 
 42 
 
 85 
 
 54 
 
 22 
 
 27 
 
 4-5 
 
 54 
 
 130 
 
 219 
 
 303 
 
 160 
 
 175 
 
 93 
 
 115 
 
 Site #9 T15 R13 S26 - Panoche Soil 
 
 0-1 
 
 1 
 
 11 
 
 8 
 
 6 
 
 11 
 
 7 
 
 4 
 
 5 
 
 1-2 
 
 2 
 
 6 
 
 2 
 
 1 
 
 1 
 
 2 
 
 2 
 
 2 
 
 2-3 
 
 23 
 
 22 
 
 7 
 
 1 
 
 4 
 
 11 
 
 10 
 
 13 
 
 3-4 
 
 14 
 
 33 
 
 13 
 
 8 
 
 3 
 
 14 
 
 11 
 
 14 
 
 4-5 
 
 1 
 
 52 
 
 18 
 
 40 
 
 2 
 
 23 
 
 23 
 
 28 
 
 Site #10 T14 R12 S26 - Lost Hills Soil 
 
 0-1 
 
 2 
 
 4 
 
 97 
 
 14 
 
 40 
 
 31 
 
 40 
 
 50 
 
 1-2 
 
 3 
 
 26 
 
 70 
 
 20 
 
 40 
 
 32 
 
 33 
 
 40 
 
 2-3 
 
 16 
 
 46 
 
 82 
 
 26 
 
 44 
 
 43 
 
 25 
 
 31 
 
 3-4 
 
 40 
 
 50 
 
 101 
 
 29 
 
 44 
 
 53 
 
 28 
 
 35 
 
 4-5 
 
 48 
 
 48 
 
 101 
 
 33 
 
 50 
 
 57 
 
 52 
 
 65 
 
 Site #11 T14 R12 S13 - Panoche Soil 
 
 0-1 
 
 79 
 
 48 
 
 29 
 
 30 
 
 30 
 
 43 
 
 21 
 
 26 
 
 1-2 
 
 61 
 
 10 
 
 8 
 
 16 
 
 15 
 
 22 
 
 22 
 
 28 
 
 2-3 
 
 17 
 
 2 
 
 3 
 
 10 
 
 15 
 
 9 
 
 7 
 
 8 
 
 3-4 
 
 11 
 
 1 
 
 5 
 
 6 
 
 17 
 
 8 
 
 6 
 
 8 
 
 4-5 
 
 7 
 
 2 
 
 6 
 
 3 
 
 13 
 
 6 
 
 5 
 
 6 
 
 (38) 
 
TABLE 11 (cont.) 
 
 Depth 
 
 
 
 
 
 
 
 
 
 
 (1) 
 
 (2) 
 
 Ft. 
 
 
 a 
 
 b 
 
 c 
 
 d 
 
 e 
 
 
 
 Avg. 
 
 C7 
 
 Om 
 
 
 
 
 Site #12 
 
 T13 R13 
 
 S23 - 
 
 Panoche 
 
 Sc 
 
 )il 
 
 
 
 0-1 
 
 
 64 
 
 5 
 
 2 
 
 1 
 
 1 
 
 
 
 14 
 
 28 
 
 34 
 
 1-2 
 
 
 13 
 
 3 
 
 1 
 
 1 
 
 1 
 
 
 
 4 
 
 5 
 
 6 
 
 2-3 
 
 
 8 
 
 2 
 
 1 
 
 3 
 
 2 
 
 
 
 3 
 
 2 
 
 3 
 
 3-4 
 
 
 14 
 
 3 
 
 7 
 
 8 
 
 9 
 
 
 
 8 
 
 4 
 
 5 
 
 4-5 
 
 
 23 
 
 3 
 
 12 
 
 6 
 
 12 
 
 
 
 11 
 
 8 
 
 9 
 
 
 
 
 Site #13 
 
 T12 R13 
 
 S25 - 
 
 Oxalis ; 
 
 3oi 
 
 .1 
 
 
 
 0-1 
 
 
 18 
 
 14 
 
 15 
 
 19 
 
 23 
 
 
 
 18 
 
 4 
 
 5 
 
 1-2 
 
 
 2 
 
 2 
 
 2 
 
 3 
 
 5 
 
 
 
 3 
 
 1 
 
 1 
 
 2-3 
 
 
 1 
 
 1 
 
 5 
 
 22 
 
 1 
 
 
 
 6 
 
 9 
 
 11 
 
 3-4 
 
 
 1 
 
 2 
 
 1 
 
 1 
 
 1 
 
 
 
 1 
 
 1 
 
 1 
 
 4-5 
 
 
 1 
 
 2 
 
 1 
 
 1 
 
 
 
 
 
 1 
 
 1 
 
 1 
 
 
 
 
 
 TABLE 12 
 
 
 
 
 
 
 
 
 
 Average Pounds Per Acre 
 
 and 
 
 Total 
 
 N in 
 
 
 
 
 
 the 
 
 ! Study A] 
 
 rea in the 0-5 
 
 Foot 
 
 So: 
 
 il 
 
 Depth 
 
 
 
 N03- 
 
 -N 
 
 
 NH3-N 
 
 Organic 
 
 N 
 
 
 
 Total N 
 
 Ibs/ac. 
 
 Tons 
 
 Ibs/ac. 
 
 Tons 
 
 Ibs/ac. 
 
 Tons 
 
 i lbs/< 
 
 ac. 
 
 Tons 
 
 258 
 
 86, 
 
 ,370 
 
 54 
 
 L8,400 
 
 5,830 
 
 1, 
 
 9 51 
 
 ,940 6,142 
 
 2, 
 
 056,600 
 
 within the individual fans, or those sites most representative of 
 them, by the acreages of the fans. The total nitrogen and pounds 
 per acre for each of the nitrogen forms on each alluvial fan are 
 listed in Table 14. 
 
 The total nitrogen in the substrata is 8,193,080 tons or about 
 24,490 pounds per acre. Nitrate N accounts for 1,496,000 tons or 
 4,470 pounds per acre of the total. The concentration of nitrate 
 N ranged from a low of 87 pounds at site 5, a Panoche soil on the 
 Los Gatos Creek fan to a high 28,3 53 pounds per acre at site 8, an 
 Oxalis soil on the Panoche-Cantua interfan. 
 
 The total organic N in the Substrata was 6,559,2 50 tons or an 
 average of 19,730 pounds per acre. The concentration of the 
 
 (39) 
 

 
 
 TABLE 13 
 
 
 
 
 
 
 NO3- 
 
 -N, NH3-] 
 
 ^ and Org 
 
 anic N in PPM 
 
 and Pounds 
 
 
 
 
 Per 
 
 Acre in 
 
 the Soil 
 
 Substrata* 
 
 
 
 Site 
 
 Depth in 
 
 NO 3 
 
 -N 
 
 NH 
 
 3-N 
 
 Organic N 
 
 Total N 
 
 No. 
 
 feet 
 5-40 
 
 PPM** 
 3.7 
 
 lbs. 
 467 
 
 PPM** 
 2.9 
 
 lbs. 
 368 
 
 PPM** 
 144 
 
 lbs. 
 18,197 
 
 lbs. 
 
 1 
 
 19,032 
 
 2 
 
 5-12.5 
 
 1.5 
 
 40 
 
 3.0 
 
 82 
 
 199 
 
 5,383 
 
 5,505 
 
 3 
 
 5-40 
 
 0.7 
 
 87 
 
 3.2 
 
 409 
 
 232 
 
 29,284 
 
 29,780 
 
 4 
 
 5-32 
 
 41.4 
 
 4,019 
 
 2.9 
 
 277 
 
 202 
 
 19,560 
 
 23,867 
 
 5 
 
 5-40 
 
 13.4 
 
 1,693 
 
 2.0 
 
 250 
 
 152 
 
 19,109 
 
 21,052 
 
 6 
 
 *** 
 
 
 
 
 
 
 
 
 7 
 
 5-6 
 
 1.6 
 
 6 
 
 3.0 
 
 11 
 
 138 
 
 497 
 
 514 
 
 8 
 
 5-40 
 
 205.0 
 
 28,353 
 
 1.8 
 
 232 
 
 118 
 
 14,810 
 
 43,395 
 
 9 
 
 5-40 
 
 135.8 
 
 17,105 
 
 2.2 
 
 282 
 
 112 
 
 14,164 
 
 31,551 
 
 10 
 
 5-40 
 
 60.5 
 
 7,642 
 
 1.1 
 
 137 
 
 108 
 
 13,573 
 
 23,352 
 
 11 
 
 5-40 
 
 2.0 
 
 252 
 
 1.5 
 
 186 
 
 14 5 
 
 17,691 
 
 18,129 
 
 12 
 
 5-30 
 
 12.3 
 
 1,106 
 
 1.4 
 
 128 
 
 18 5 
 
 16,686 
 
 17,920 
 
 13 
 
 5-10 
 
 1.8 
 
 32 
 
 2.3 
 
 42 
 
 235 
 
 4,230 
 
 4,304 
 
 * 5-40 feet or to water table 
 
 ** Based on Apparent Specific Gravity of 1.32 
 
 *** Water Table at 5 feet 
 
 individual sites ranged from a minimum of 13,573 to a maximum of 
 29,284 pounds per acre. Although this is a large variation, the 
 percentage differences are relatively small when compared with the 
 variations that occur in the nitrate concentrations. 
 
 The distribution of the relative concentrations of NO3-N, NH3-N and 
 organic N throughout the profile at all the transect sites is shown 
 in Figures 4 through 16. 
 
 The nitrate -N generally was greatest in the upper part of the sub- 
 strata, there were exceptions and the peak concentrations occurred 
 at any depth. 
 
 The ammonia concentrations were relatively low, generally less than 
 five parts per million. Although percentage-wise there was a large 
 variation between sites, the differences in actual quantities when 
 compared to differences in the other forms were small. 
 
 Although the quantity of organic N decreased with depth, it was 
 still the dominant type except in site 8. At site 9 organic 
 N was only slightly more than NO3-N. A few Substrata contained 
 
 (40) 
 
00 -» m 
 
 ^^ ^ rsi 
 
 ^ ^ CM 
 
 J (lb 
 
 
 6 «^ 4J 
 
 •^ -H CL. 
 
 (41) 
 
SITE NO. I-OXALIS SOIL 
 
 4000-1 
 
 1000- 
 
 500 
 
 c 100- 
 
 5 - 
 
 ORGANIC N - 
 
 i 
 
 NH3-N- 
 
 
 NO3-N- 
 
 11 
 
 rnTT, 
 
 I p I I I J- r' 'i' r i' c rt t I j t 1 1 1 [ 1 » » » \ t ii 1 |r 1 i 1 [ ' i ' l' r f 
 D«pth in Feet 
 
 FIG. 4- DISTRIBUTION OF NO3-N, NH3-N AND 
 ORGANIC-N BY SAMPLING DEPTH 
 
 (42) 
 
SITE NO. 2-LETHENT SOIL 
 
 4000-1 
 
 1000- 
 
 500 
 
 100 — 
 
 ORGANIC N - 
 
 i 
 
 NH3-N- 
 
 
 
 ^ 
 
 NO3-N- 
 
 ■: 
 
 I ~ 'I'f'f'ri'i'i 1 1 1 1 I'l I I I I I 1 1 I I 1 1 1 1 1 II I 1 1 1 1 1 I 1 1 I I 
 
 Depth in Feet 
 
 FIG. 5 - DISTRIBUTION OF NO3-N, NH3-N AND 
 ORGANIC -N BY SAMPLING DEPTH 
 
 (43) 
 
SITE NO. 3-PANOCHE SOIL 
 
 4000-1 
 
 lOOO- 
 
 500- 
 
 100 
 
 ORGANIC 
 
 N-i 
 
 NH,-N- 
 
 ' p I 1 1 1 t t I rp ' r t I I ' I f i ' I j r I I I I 1 1 I » I I I I I I I 1 1 I 
 
 - N N M lO ♦ 
 
 D«pth in Feet 
 
 FIG. 6- DISTRIBUTION OF NO3-N, NH3-N AND 
 ORGANIC-N BY SAMPLING DEPTH 
 
 (44) 
 
SITE NO. 4-PANOCHE SOIL 
 
 4000—1 
 
 1000 
 
 500 - 
 
 E 
 
 100 
 
 ORGANIC N - 
 
 i 
 
 NHj-N- 
 
 
 
 rf 
 
 NO3-N- 
 
 iu 
 
 1 1 I I I'l'i- f i r ^' f r rt'i' rm 'i'f r i i'j ' ^ ^ '1 I I I I I 1 1 I 1 1 I I 
 o « o « 8 « 8 
 
 D«pth in Feet 
 
 FIG. 7- DISTRIBUTION OF NO3-N, NH3-N AND 
 ORGANIC-N BY SAMPLING DEPTH 
 
 (4S) 
 
SITE NO. 5-OXALIS SOIL 
 
 4000-1 
 
 1000- 
 
 500 
 
 J& 
 
 100- 
 
 ORGANIC N - 
 
 i 
 
 NHj-N- 
 NO3-N- 
 
 
 ^ 
 
 I p i T r ^ - vvv i 'f i n I I I I I n I I 1 1 1 1 1 I I I 1 1 I 1 1 I 1 1 I 
 
 D«pth in Feet 
 
 FIG. 8 - DISTRIBUTION OF NO3-N, NH^-N AND 
 ORGANIC-N BY SAMPLING DEPTH 
 
 (46) 
 
SITE NO 6-LETHENT SOIL 
 
 4000-1 
 
 1000- 
 
 500 
 
 100- 
 
 50 - 
 
 10- 
 
 5 '■■:■ 
 
 ORGANIC N - 
 
 i 
 
 NHj-N- 
 
 
 NO3-N — 
 
 rr 
 
 • I ' l " > V > " | II I I ; I I I I I I I I >[ I I I I J I I I T I I I I I I I I I I J 
 
 « W |l» fO ^ 
 
 D«pth In Feet 
 
 FIG. 9- DISTRIBUTION OF NO3-N, NH3-N AND 
 ORGANIC-N BY SAMPLING DEPTH 
 
 (47) 
 
SITE NO, 7- LEVIS SOIL 
 
 4O00-T 
 
 1000- 
 
 500 
 
 100- 
 
 10- 
 
 5 - 
 
 ORGANIC N - 
 
 i 
 
 NHj-N- 
 NO3-N- 
 
 
 i' I ' f 1 I I I I I I I I I 1 I I I I I I I I I I I I I [ I I » I I I I » I I 
 
 2 !G 8 S 5{ 
 
 D«pth in Feet 
 
 FIG. 10- DISTRIBUTION OF NO3-N, NH3-N AND 
 ORGANIC-N BY SAMPLING DEPTH 
 
 (48) 
 
SITE NO. 8-OXALIS SOIL 
 
 4000—1 
 
 1000- 
 
 500 
 
 100- 
 
 10- 
 
 5 - 
 
 ''"'■ 
 
 ORGANIC N - 
 
 i 
 
 NH3-N- 
 
 
 
 ^ 
 
 NO3-N- 
 
 *M 
 
 • 1 1 I I n I t'tr i' t I f I ' l I r I I I I I I I I 'l I I I I I I I I I I 1 1 1 ' 
 
 D«pth in Feet 
 
 FIG. II - DISTRIBUTION OF NO3-N, NH3-N AND 
 ORGANIC-N BY SAMPLING DEPTH 
 
 (49) 
 
SITE NO. 9-PANOCHE SOIL 
 
 4000-1 
 
 1000 — > 
 
 500 
 
 100 — 
 
 10 — 
 
 5 - 
 
 -: 2f 
 
 ORGANIC N - 
 
 
 NHj-N- 
 
 
 NO3-N- 
 
 
 pTr i* !' r I I ' l I I I 1 1 I I I I 1 1 I I 1 1 1 1 1 I I I 1 1 I I I I 1 1 I 
 
 Dtpth in Feet 
 
 FIG. 12- DISTRIBUTION OF NO3-N, NH3-N AND 
 0R6ANIC-N BY SAMPLING DEPTH 
 
 (50) 
 
SITE NO. 10 -LOST HILLS SOIL 
 
 4000-1 
 
 1000 -; 
 
 500 
 
 100 — 
 
 o 50 - 
 
 10- 
 
 5 - 
 
 ORGANIC N - 
 
 i 
 
 NHj-N- 
 NO3-N — 
 
 r: 
 
 I — Ti' f t'i' TV vrf r vvfp ' v rfp ' fr r yff f T [ » 1 < 1 | 1 1 1 i " 
 
 Dtpth in Feet 
 
 FIG. 13- DISTRIBUTION OF NO3-N, NH3-N AND 
 ORGANIC -N BY SAMPLING DEPTH 
 
 (SI) 
 
SITE NO. II- PANOCHE SOIL 
 
 4000-1 
 
 1000- 
 
 500- 
 
 JS 
 
 100 — 
 
 ORGANIC N - 
 
 i 
 
 NHj-N- 
 NO3-N- 
 
 
 I p'v t'f y ^ 'vi' i ' i ' i 'V i I y I I I 1 1 I I I I I 1 1 I I I 'v i-ri'i f t rv 
 
 D«pth in Feet 
 
 FIG. 14- DISTRIBUTION OF NO3-N, NH3-N AND 
 ORGANIC-N BY SAMPLING DEPTH 
 
 (52) 
 
SITE NO. 12 - PANOCHE SOIL 
 
 4000-1 
 
 1000- 
 
 500 
 
 100- 
 
 10 — 
 
 5 - 
 
 ORGANIC N - 
 
 i 
 
 NH3-N- 
 
 
 
 ^ 
 
 NO3-N — 
 
 ^ 
 
 ' {' ' I » 'I I ' I I I I [ I I I I [ I I I I [ I I I I J I I I T ] I I I I I I I I II 
 
 - N W {15 rO 'T 
 
 D«pth in Feet 
 
 FIG. 15- DISTRIBUTION OF NO3-N, NH3-N AND 
 ORGANIC-N BY SAMPLING DEPTH 
 
 (53) 
 
SITE NO. 13- OXALIS SOIL 
 
 4000-1 
 
 1000- 
 
 5 - 
 
 J" 
 
 ORGANIC N - 
 
 i 
 
 NH3-N- 
 NO3-N- 
 
 
 I p ' f l' f | Tf l T ^ I I I I I I I I I I I I I r [ I I I I I I I I I J I I I I I 
 
 Dtpth in Feet 
 
 FIG. 16- DISTRIBUTION OF NO3-N, NH3-N AND 
 ORGANIC-N BY SAMPLING DEPTH 
 
 (54) 
 
less than 10, however, normally they contained more than 100 parts 
 per million. The organic N concentrations were higher on the 
 alluvial fans than on the interfans and in both fan and interfan 
 areas there is an increase in concentration from north to south. 
 
 Sites No. 8, 9, and 10 have unusually high concentrations of 
 nitrates. They represent different soil series and physiographic 
 position. However, they do have a common factor in that they are 
 located on similar geomorphic units; that is, interfan areas between 
 the larger streams, Little Panoche , Panoche and Cantua Creeks. These 
 areas have been subjected to less surface flooding and consequently 
 there has been less leaching of the nitrates from the soil profile. 
 There is also the possibility that because less water has moved 
 through the soils there have been fewer saturated conditions there- 
 fore less denitrif ication has occurred to reduce the nitrate con- 
 centrations. 
 
 Nitrogen in Groundwater 
 
 About 2 5 percent of the ultimate water demand will be met from the 
 groundwater of the area, therefore, it is necessary to know the 
 amount of nitrate in this body of water in order to predict the 
 nitrate-nitrogen content of the agricultural drainage effluent. 
 Generally data from the wells above the Corcoran clay show a 
 decrease in the nitrate concentration with increasing depth. The 
 wells which have their primary yields from the Sierra sediments 
 have lower nitrate concentrations than those wells that produce 
 from the Coast Range sediments. 
 
 A description of nitrate concentrations in water above the Corcoran 
 clay by well depth interval as prepared by the Geology Branch, USER, 
 Sacramento is presented below: 
 
 0-50 foot well depth 
 
 As shown in Tables 15 through 19, the highest NO3-N values appear to 
 be in the 0-50 foot depth on the Los Gatos-Zapatos interfan in Coast 
 Range material. However, this concentration of 122 mg/1 NO3-N is 
 based on an average of only two samples. The 0-50 foot depth on the 
 Panoche-Cantua interfan has a mean of 52 mg/1 NO3-N in Coast Range 
 sediments based on 16 samples. The standard deviation for the 52 mg/1 
 mean approached 68 mg/1 indicating a wide range of NO3-N concentrations 
 within the 0-50 foot depth interval. 
 
 On the Panoche fan a mean NO-j-N concentration of about 36 mg/1 in 
 Coast Range sediments was computed for 53 samples including a very 
 high NO3-N value (560 mg/1) reported for USER geohydrologic obser- 
 vation hole No. 14S/14E/28R2. Excluding this high analysis, the mean 
 NO7-N content was 16 mg/1, with the next highest NO^-N being 150 mg/1. 
 
 (55) 
 
TABLE 15 
 
 Summary a/ of Nitrate Nitrogen and Standard Deviations in Milligrams 
 per Liter for Wells and USER Geohydrologic Observation Holes Above the 
 Corcoran Clay - 0-50 Foot Depth 
 
 0-50 Ft. well depth 
 
 Yield primarily from: 
 GEOMORPHIC UNITS No. of Sierran Coast Range 
 
 analyses sediments sediments 
 
 LOS BANCS CR. - L. PANOCHE INTERFAN 
 
 1 
 
 
 
 
 
 10. 
 
 ,2 
 
 
 
 LITTLE PANOCHE FAN 
 
 5 
 
 
 
 
 
 IB. 
 
 ,b 
 
 + 
 
 14.0 
 
 LITTLE PANOCHE - PANOCHE INTERFAN 
 
 3 
 
 
 
 
 
 /. 
 
 ,b 
 
 + 
 
 4.6 
 
 PANOCHE FAN 
 
 53b/ 
 52c/ 
 
 1 
 
 1. 
 
 .0 
 
 
 
 2b, 
 
 15. 
 
 .9 
 .6 
 
 + 
 
 76.3 
 24.8 
 
 PANOCHE - CANTUA INTERFAN 
 
 16 
 
 
 
 
 
 52, 
 
 .5 
 
 + 
 
 67.6 
 
 CANTUA FAN 
 
 14 
 
 
 
 
 
 6. 
 
 .1 
 
 + 
 
 9.3 
 
 CANTUA - LOS GATOS INTERFAN 
 
 7 
 
 
 
 
 
 22, 
 
 .7 
 
 + 
 
 29.6 
 
 LOS GATOS FAN 
 
 40 
 16 
 
 2. 
 
 .4 
 
 t 4' 
 
 ,0 
 
 30, 
 
 .1 
 
 + 
 
 77.3 
 
 LOS GATOS - ZAPATOS INTERFAN 
 
 2 
 
 
 
 
 
 122, 
 
 .4 
 
 (aver. ) 
 
 MENDOTA - FIREBAUGH AREA 
 
 1 
 2 
 
 
 
 .9 
 
 (aver 
 
 .) 
 
 
 
 0.1 
 
 TOTAL SAMPLES ABOVE 
 CORCORAN CLAY: 244 
 
 160 
 
 
 
 
 
 
 
 
 
 a/Expressed as arithmetic mean plus or minus standard deviation. 
 b/Includes analysis from USER geohydrologic observation hole No. 14S/ 
 ~ 14E-28R2 with a nitrate nitrogen value of 562 mg/1. 
 c/Excludes analysis from USBR geohydrologic observation hole No. 14S/ 
 ~ 14E-28R2. 
 
 (56) 
 
TABLE 16 
 
 Summary of Nitrate Nitrogen and Standard Deviations in Milligrams 
 
 per Liter for Wells and USER Geohydrologic Observation Holes Above the 
 
 Corcoran Clay - 50-150 Foot Depth 
 
 GEOMORPHIC UNITS 
 
 50-150 
 
 No. of 
 analyses 
 
 ft. well 
 Yield pr 
 Sierran 
 
 sediments 
 
 depth 
 
 imarily from: 
 
 Coast Range 
 
 sediments 
 
 LOS BANGS CR. - L. PANOCHE INTERFAN 
 
 LITTLE PANOCHE FAN 
 
 LITTLE PANOCHE - PANOCHE INTERFAN 
 
 PANOCHE FAN 
 
 2 
 
 
 
 1.4 (aver.) 
 
 PANOCHE - CANTUA INTERFAN 
 
 1 
 
 
 
 93.5 
 
 CANTUA FAN 
 
 1 
 
 
 
 0.1 
 
 CANTUA - LOS GATOS INTERFAN 
 
 1 
 
 
 
 0.7 
 
 LOS GATOS FAN 
 
 9 
 
 
 
 29.3 + 32.4 
 
 LOS GATOS - ZAPATOS INTERFAN 
 
 MENDOTA - FIREBAUGH AREA 
 
 3 
 
 0.5 
 
 + 0.3 
 
 
 TOTAL SAMPLES ABOVE 
 CORCORAN CLAY: 244 
 
 17 
 
 
 
 
 (E7) 
 
TABLE 17 
 
 Summary of Nitrate Nitrogen and Standard Deviation in Milligrams per 
 Liter for Wells and USER Geohydrologic Observation Holes Above the 
 Corcoran Clay - 150-300 Foot Depth 
 
 150-300 ft. well depth 
 
 Yield primarily from:" 
 
 No. of Sierran Coast Range 
 
 analyses sediments sediments 
 
 GEOMORPHIC UNITS 
 
 LOS BANCS CR. - L. PANOCHE INTERFAN 
 
 LITTLE PANOCHE FAN 
 
 LITTLE PANOCHE - PANOCHE INTERFAN 
 
 PANOCHE FAN 
 
 7 
 
 1 
 
 0. 
 
 ,5 
 
 51, 
 
 .0 
 
 + 117. 
 
 ,2 
 
 PANOCHE - CANTUA INTERFAN 
 
 1 
 
 
 
 
 .6 
 
 
 
 CANTUA FAN 
 
 CANTUA - LOS GATOS INTERFAN 
 
 LOS GATOS FAN 
 
 2 
 
 1 
 
 0, 
 
 ,3 
 
 5, 
 
 .8 
 
 (aver. 
 
 ) 
 
 LOS GATOS - ZAPATOS INTERFAN 
 
 MENDOTA - FIREBAUGH AREA 
 
 6 
 18 
 
 0, 
 
 ,3 + 0.2 
 
 0, 
 
 .4 
 
 + 0.5 
 
 
 TOTAL SAMPLES ABOVE 
 CORCORAN CLAY: 244 
 
 36 
 
 
 
 
 
 
 
 (58) 
 
TABLE 18 
 
 Summary of Nitrate Nitrogen and Standard Deviations in Milligrams per 
 Liter for Wells and USER Geohydrologic Observation Holes Above the 
 Corcoran Clay - 300-600 Foot Depth 
 
 GEOMORPHIC UNITS 
 
 300-600 ft. well depth 
 
 Yield primarily from~ 
 No . of Sierran Coast Range 
 analyses sedinents sediments 
 
 LOS BANGS CR. - L. PANOCHE INTERFAN 
 
 LITTLE PANOCHE FAN 
 
 LITTLE PANOCHE - PANOCHE INTERFAN 
 
 PANOCHE FAN 
 
 5 
 
 
 
 2 
 
 + 0.3 
 
 
 
 PANOCHE - CANTUA INTERFAN 
 
 3 
 
 
 
 9 
 
 + 0.5 
 
 
 
 CANTUA FAN 
 
 1 
 2 
 
 
 
 2 
 
 (aver 
 
 21 
 ) 
 
 
 
 CANTUA - LOS GATOS INTERFAN 
 
 LOS GATOS FAN 
 
 1 
 8 
 
 1 
 
 4 
 
 + 2.6 
 
 10 
 
 6 
 
 LOS GATOS - ZAPATOS INTERFAN 
 
 MENDOTA - FIREBAUGH 
 
 1 
 2 
 
 
 
 1 
 
 (aver. 
 
 
 ) 
 
 1 
 
 TOTAL SAMPLES ABOVE 
 CORCORAN CLAY: 244 
 
 23 
 
 
 
 
 
 
 (59) 
 
TABLE 19 
 
 Sununary of Nitrate Nitrogen and Standard Deviation in Milligrams per 
 Liter for Wells and USER Geohydrologic Observation Holes Above the 
 Corcoran Clay - 600-800 Foot Depth 
 
 GEOMORPHIC UNITS 
 
 600- 
 
 No. of 
 analyses 
 
 ■800- ft. well depth 
 
 Yield primarily from: 
 Sierran Coast Range 
 sediments sediments 
 
 LOS BANOS CR - L. PANOCHE INTERFAN 
 
 LITTLE PANOCHE FAN 
 
 LITTLE PANOCHE - PANOCHE INTERFAN 
 
 PANOCHE FAN 
 
 PANOCHE - CANTUA INTERFAN 
 
 CANTUA FAN 
 
 CANTUA - LOS GATOS INTERFAN 
 
 LOS GATOS FAN 
 
 
 5 
 2 
 
 0.2 + 0.5 
 0.5 (aver. ) 
 
 LOS GATOS - ZAPATOS INTERFAN 
 
 
 1 
 
 5.6 
 
 MENDOTA - FIREBAUGH AREA 
 
 TOTAL SAMPLES ABOVE 
 CORCORAN CLAY: 244 
 
 
 8 
 
 
 (60) 
 
Little Panoche fan has a mean NO3-N concentration of 18 mg/1 for 
 five analyses with individual analyses ranging from 4 mg/1 to 40 
 mg/1 in the 0-50 foot interval. 
 
 Generally NO3-N concentrations for the 0-50 foot depth in wells 
 which obtain their yield from Sierran sediments is comparatively low, 
 ranging from to 14 rag/1 (Los Gatos fan). Nitrate -N concentrations 
 for USER holes in Coast Range sediments in the interval are high, 
 ranging from a trace up to 460 mg/1, as mentioned above. About five 
 holes had nitrates in excess of 225 mg/1. 
 
 50-150 foot well depth 
 
 In the 50-150 foot depth range, one analysis on the Panoche -Cant ua 
 interfan was 93 mg/1 in Coast Range sediments. On the Los Gatos 
 fan the average for this depth was 29 ppm in Coast Range sediments. 
 On the other fans and interfans in this depth range, mean NO3-N was 
 less than 2 mg/1, based on a small number of analyses in both Coast 
 Range and Sierran sediments. 
 
 150-300 foot well depth 
 
 In the 150-300 foot depth interval Panoche fan had a high concen- 
 tration of nitrate in Coast Range sediments; based on seven analyses 
 the mean NO3-N concentration was about 51 mg/1 with a standard 
 deviation of 117 rag/1. The range was from 1 to 320 mg/1. For other 
 fans and sediments concentrations in this depth range were as much 
 as 7 mg/1 but were generally less than 1 mg/1. 
 
 300-600 foot well depth 
 
 In the 300-600 foot depth interval, NO3-N concentrations are generally 
 low, ranging from 0.1 to 2 mg/1, principally from Sierran aquifiers. 
 Two wells in this depth zone producing from Coast Range sediments 
 on the Cantua and Los Gatos fans had 22 and 10 rag/1, respectively 
 of NO3-N. 
 
 600-800 foot well depth 
 
 In the 600-800 depth interval, nitrate was low in both Sierran and 
 Coast Range sediments with the highest NO,-N being 6 mg/1 in Coast 
 Range sediments on the Los Gatos-Zapatos interfan. 
 
 The average NO3-N concentration, about 0.5 mg/1, of the irrigation 
 water from the wells in the area is much less than the average 
 concentration of water in the material above the Corcoran as listed 
 in Table 15 through 19. This is particularly true of the water in 
 all depths of the Coast Range sediments and in the 0-50 depth of 
 
 (61) 
 
the Sierran sediments, indicating that relatively small amounts of 
 irrigation water is obtained from these sources. Also, as many of 
 the wells are drilled below the Corcoran clay to depths of 2,000 
 feet or greater they pick up most of their water from strata not 
 shown in this report. 
 
 Nitrogen Transformation and Movement in Lysimeters 
 
 The movement of residual nitrogen and applied fertilizer nitrogen 
 in lysimeters was monitored under leaching and cropping regimes. 
 
 The initial NO3-N levels of the soils ranged from 12 ppm in the 
 Panoche clay subsoil to 115 ppm in the Lethent clay loam surface. 
 The NO3-N levels in leachates collected during initial leaching and 
 before fertilization ranged from 4,290 ppm in the Oxalis clay to 
 560 ppm in the Panoche fine sandy loam. These high levels are 
 believed due primarily to the change in the environment of the soils 
 as a result of the screening, mixing and aeration during the filling 
 of the lysimeters. These actions increased microbial activity which 
 encouraged mineralization of some of the native organic nitrogen 
 to nitrates. 
 
 After the high initial nitrate concentrations were recorded, a rapid 
 drop in the nitrate levels occurred as additional water moved through 
 the columns. When sufficient water had been applied to reduce the 
 nitrate-N levels in the soil extracts from all sampling depths of 
 the soil columns to less than 10 ppm, the NO3-N concentrations in 
 the leachates ranged from about 11 ppm for the Panoche fine sandy 
 loam to about 115 ppm for the Oxalis clay. After the barley was 
 planted and the 1% enriched fertilizer applied, periodic samples 
 were collected of the soil extracts at three depths in the columns 
 and from the leachates. Data resulting from the analyses of these 
 samples, based primarily on the atom percent excess -'■% , are presented 
 in Tables 20 through 28. These data are averages of values from 
 duplicate columns of each treatement. 
 
 Data for nitrogen content and the percentages which are attributable 
 to ferti3j.zer nitrogen in the "A" depths, 9 to 18 inches, are presented 
 in Table 20. These data show that at this depth the highest percent- 
 age of fertilizer nitrogen appeared in those soils to which KNO3 
 was applied. In Panoche fine sandy loam and Lethent sandy clay loam, 
 respectively, 81 and 65 percent of the total nitrogen collected in 
 the soil extract was fertilizer nitrogen. By comparison 14 and 27 
 percent of the nitrogen in the extract was fertilizer nitrogen when 
 (NH4)2S04 was applied to Panoche clay loeim and Oxalis clay and when 
 sulfur coated urea was applied to Panoche fine sandy loam 2 5 percent 
 of the extract from "A" depth was fertilizer nitrogen. 
 
 This would indicate that much of the ammonia-N is adsorbed by the 
 
 (62) 
 
clay complex of the soil near the soil surface. Since only 30 per- 
 cent of the sulfur coated urea was readily soluble and the remainder 
 was treated to dissolve slowly, movement of nitrogen from the urea 
 fertilizer could be expected to be approximately 30 percent of N 
 movement from KNO3 assuming appreciable hydrolosis did not occur. 
 The data are in accord with these proportions. However, the system 
 is complicated by nitrogen release from sulfur coated urea, hydrolosis 
 of urea, nitrification and soil textural differences, therefore, the 
 apparent proportionality may have resulted from compensating effects. 
 
 The nitrogen content and the percent fertilizer nitrogen in the soil 
 extract at the "B" depths, 24 to 39 inches, are listed in Table 21. 
 
 TABLE 20 
 
 Nitrogen Content and Percent of Fertilizer 
 Nitrogen in Soil Extracts from "A" Depths 
 December 16, 1968 - August 18, 1969 
 
 Soil Type Fertilizer 
 
 Wate 
 
 r Applied 
 
 Probe Depth 
 
 Total N 
 
 Fertilizer N 
 
 
 
 
 In 
 
 
 In 
 
 mg 
 
 % 
 
 Panoche CL 
 
 (NH4)2S04 
 
 
 60.6 
 
 
 16 
 
 13.2 
 
 13.6 
 
 Panoche FSL 
 
 KNO3 
 
 
 60,6 
 
 
 15 
 
 49.5 
 
 81.4 
 
 Lethent CI 
 
 KNO3 
 
 
 60.6 
 
 
 9 
 
 34.2 
 
 66.1 
 
 Panoche FSL 
 
 S:Urea-N 
 
 
 60.6 
 
 
 11 
 
 15.2 
 
 25.0 
 
 Oxalis C 
 
 (NH4)2S04 
 
 
 60.6 
 
 
 18 
 
 16.5 
 
 27.3 
 
 
 
 
 TABLE 
 
 21 
 
 
 
 
 Nitrogen Content and Percent of Fertilizer 
 Nitrogen in Soil Extracts from "B" Depths 
 December 16, 1968 - August 18, 1969 
 
 Soil Type Fertilizer 
 
 Wate 
 
 r Applied 
 
 Probe Depth 
 
 Total N 
 
 Fertilizer N 
 
 
 
 
 In 
 
 In 
 
 mg 
 
 % 
 
 Panoche CL 
 
 (NH4)2S04 
 
 
 60.6 
 
 39 
 
 23.5 
 
 2.1 
 
 Panoche FSL 
 
 KNO3 
 
 
 60.6 
 
 39 
 
 23.0 
 
 4.8 
 
 Lethent CL 
 
 Kri03 
 
 
 60.6 
 
 24 
 
 14.2 
 
 23.9 
 
 Panoche FSL 
 
 S:Urea-N 
 
 
 60.6 
 
 33 
 
 14.4 
 
 4.2 
 
 Oxalis C 
 
 (NH4)2S04 
 
 
 60.6 
 
 31 
 
 36.0 
 
 1.4 
 
 The percent of fertilizer N of the total N collected from the "B" 
 depths was less than 4.8 with the exception of the Lethent clay loam. 
 The higher percentage of fertilizer N in the Lethent columns may have 
 been because the suction probes were higher in the columns. These 
 low values for the other columns indicate that little movement of the 
 fertilizers occurred to depths of 31 to 39 inches. 
 
 (63) 
 
The nitrogen content and percent fertilizer N for the "C" depth are 
 shown in Table 22. At the most, 4.5 percent of the N collected from 
 the probe came from the applied fertilizer. The highest percentage 
 of fertilizer N was from the Lethent soil and least was from the 
 Panoche fertilized with sulfur coated urea. These low values indicate, 
 as did those of the "B" depths, that a very small percentage of the 
 applied N moved through the soil columns. 
 
 TABLE 22 
 
 Nitrogen Content and Percent < 
 
 in Soil Extracts from "C 
 
 December 16, 1968 - August 
 
 Df Fertilizer 
 " Depths 
 18, 1969 
 
 
 Soil Type Fertilizer 
 
 Panoche CL (NH4)2S04 
 Panoche FSL KNO3 
 Lethent CL KNO3 
 Panoche FSL S:Urea-N 
 Oxalis C (NH4)2S04 
 
 Water Applied 
 In 
 
 60.6 
 60.6 
 60.6 
 60.6 
 60.6 
 
 Probe Depth 
 In 
 
 63 
 62 
 60 
 58 
 56 
 
 Total N 
 mg 
 
 25.9 
 
 41.6 
 19.8 
 20.9 
 20.5 
 
 Fertilizer N 
 % 
 
 1.5 
 2.2 
 4.5 
 1.4 
 1.5 
 
 Both the total nitrogen removed in the leachate and the percent of 
 this total that was fertilizer nitrogen are listed in Table 23. The 
 total N in the leachates ranged from 163 to 1010 milligrams, however, 
 of these amounts less than 1.5 percent was from the applied fertilizer 
 N. 
 
 TABLE 23 
 
 Nitrogen Content and Percent Fertilizer 
 Nitrogen in the Leachate 
 December 16, 1968 - August 18, 1969 
 
 Soil Type 
 
 Panoche CL 
 Panoche FSL 
 Lethent CL 
 Panoche FSL 
 Oxalis C 
 
 Fertilizer 
 
 (NH4)2S04 
 
 KNO3 
 
 KNO3 
 
 S:Urea-N 
 
 (NH4)2S04 
 
 Water Applied 
 In 
 
 60.6 
 60.6 
 60.6 
 60.6 
 60.6 
 
 Total N 
 mg 
 
 244 
 503 
 163 
 302 
 
 1010 
 
 Fertilizer N 
 % 
 
 0.5 
 1.3 
 0.7 
 0.8 
 
 0.2 
 
 The total nitrogen removed in the soil extracts and leachates and 
 
 the percentage of these values that were fertilizer nitrogen are shown 
 
 in Table 24. Although the total N ranged from 231 milligrams in the 
 
 (64) 
 
Lethent clay loam to 1083 milligrams in the Panoche fine sandy loam, 
 only a small percentage of these totals were from fertilizer N. The 
 percentages of fertilizer nitrogen in the total removed varied from 
 0.7 percent in the Oxalis clay to 12.2 percent in the Lethent clay 
 loam. The higher percentages of fertilizer nitrogen recovered from 
 those columns using KNO3 are due primarily to the large quantities 
 extracted from the "A" and "B" depths in these soils. 
 
 Total Nitrogen Content of Soil Extracts, and Leachates 
 
 and Percent Fertilizer Nitrogen for the Period 
 
 December 13, 1968 to August 18, 1969 
 
 
 
 (Soil ■ 
 
 - Fertilizer) 
 
 Fertilizer 
 
 Soil Type 
 
 Fertilizer 
 
 
 N 
 
 N 
 
 
 
 mg 
 
 % of Total N 
 
 Panoche CL 
 
 (NH4)2S04 
 
 
 307 
 
 1.2 
 
 Panoche FSL 
 
 KNO3 
 
 
 619 
 
 7.9 
 
 Lethent CI 
 
 KNO3 
 
 
 231 
 
 12.2 
 
 Panoche FSL 
 
 S:Urea-N 
 
 
 353 
 
 2.0 
 
 Oxalis C 
 
 (NH4)2S04 
 
 
 1083 
 
 0.7 
 
 The fertilizer nitrogen recovered as a percentage of the total fer- 
 tilizer applied is shown in Table 25. The largest percentage, 3.91, 
 of the fertilizer N recovered was from the Panoche fine sandy loam 
 soil treated with KNO3 fertilizer. The smallest percentage, 0.30 
 or 3.8 milligrams, was from the Panoche clay loam which was treated 
 with (NH4)2S04. The most significant of these data are the amount 
 of N recovered in the leachates. This is the quantity which under 
 field conditions would enter the groundwater. The data show that 
 the largest percentage of fertilizer nitrogen was recovered from 
 the leachate of the light textured soil treated with KNO3. It was 
 a very small amount, representing 0.54 percent, 6.7 milligrams, of 
 the total fertilizer applied. The least amount, 0.09 percent, 1.1 
 milligrams, was recovered from the Panoche clay loam soil that was 
 treated with (NH4)2S04. 
 
 The total amounts of nitrate N in leachates from various soil columns 
 treated with fertilizers and similar columns in which no fertilizers 
 were applied are shown in Table 25. 
 
 The total NO3-N removed varied in the fertilized columns from 1002 
 milligrams in the Oxalis clay to 28 milligrams in the Lethent clay 
 loam and in the control columns from 788 milligrams in the Oxalis 
 clay to 44 milligrams in the Lethent clay loam. As noted in Table 
 25, the maximum amount of fertilizer nitrogen recovered in the 
 leachate was 0.54 percent or 6.7 milligrams from the Panoche fine 
 sansy loam soil treated with KNO, . Lesser amounts of fertilizer 
 
 (65) 
 
TABLE 2 5 
 
 Recovery of Fertilizer Nitrogen from All Probes 
 
 and Leachate for the Period - December 15, 
 
 1968 - August 18, 1969 
 
 
 Soil 
 Type 
 
 
 
 
 Sample 
 
 Depth 
 
 
 
 
 Fertilizer 
 
 A 
 
 B 
 
 
 C 
 
 Leachate 
 
 Total 
 
 (NH4)2S04 
 
 KNO3 
 
 KNO3 
 
 S:Urea- 
 
 (NH4)2S04 
 
 Pan.CL 
 Pan.FSL 
 Le. CL 
 Pan.FSL 
 Ox. C 
 
 % 
 
 0. 
 3. 
 
 1. 
 0. 
 0. 
 
 ,14 
 ,22 
 ,81 
 ,30 
 ,36 
 
 mg 
 
 1, 
 
 40. 
 
 22, 
 
 3, 
 
 4. 
 
 % mg 
 
 .8 0.04 0.5 
 ,3 0.09 1.1 
 ,6 0.27 3.4 
 ,8 0.05 0.6 
 ,5 0.04 0.5 
 
 % 
 
 0, 
 0, 
 0, 
 0, 
 0, 
 
 mg 
 
 ,03 0.4 
 .07 0.9 
 ,07 0.9 
 ,02 0.3 
 ,02 0.3 
 
 % mg 
 
 0.09 1.1 
 0.54 6.7 
 0.10 1.2 
 0.18 1.3 
 0.16 2.0 
 
 % 
 
 0, 
 3, 
 2, 
 0, 
 0, 
 
 mg 
 
 ,30 3.8 
 ,91 48.9 
 ,24 28.1 
 ,56 7.0 
 ,58 7.3 
 
 
 
 
 
 
 TABLE 26 
 
 
 
 
 
 
 Nitrate -N Recovered in the Leachate of Soil 
 
 Columns for the Period - December 16, 1958 - 
 
 August 18, 1969* 
 
 Soil Type 
 
 Panoche CL 
 Panoche FSL 
 Lethent CL 
 Panoche FSL 
 Oxalis C 
 
 Fertilizer 
 
 (NH4)2S04 
 
 XNO3 
 
 KNO3 
 
 S:Urea-N 
 
 (NH4)2S04 
 
 Nitrate N in Leachate 
 Control Fertilized 
 
 mg 
 
 mg 
 
 133 
 
 143 
 
 259 
 
 431 
 
 44 
 
 28 
 
 259 
 
 233 
 
 788 
 
 1002 
 
 Determined by measurements with the Orion Nitrate probe, 
 
 nitrogen were recovered from the other columns. Although large 
 differences existed between the control arid the fertilized columns 
 for two of the soils and treatments (Table 26) these differences 
 probably were due to analytical and soil variability rather than 
 contributions from the applied fertilizers. 
 
 The significance of these data showing relatively large amounts of 
 nitrogen removed from the columns is that only a very small percentage 
 came from the applied fertilizers. Since the N in the leachate did 
 not originate from the fertilizer applied during the study and the 
 amount in the applied water was small, it had to come from the 
 nitrogen in the soil at the start of the study. 
 
 The percentages of applied fertilizer nitrogen recovered by cropping 
 are listed in Table 27. The highest percentage recovery by the barley 
 was 73 percent from the Panoche fine sandy loam treated with KNO3. 
 
 (66) 
 
The lowest recovery, 4 7 percent, was from the urea treated Panoche 
 fine sandy loam. This was probably due to the slow release rate of 
 the sulfur coated urea. The recovery rates in the other treatments 
 ranged from 63 to 65 percent. 
 
 TABLE 27 
 
 Recovery of Applied Fertilizer Nitrogen in 
 the Barley and Grain Sorghum 
 
 Fertilizer Soil Type 
 
 Barley (%AFN)' 
 
 Grain Sorghum (%AFN) 
 
 Straw Grain Total Straw Seed Total 
 
 (NH4)2S04 
 
 Panoche CL 
 
 17.9 
 
 47.7 
 
 65.6 
 
 1.00 
 
 1.87 
 
 2 
 
 87 
 
 KNO3 
 
 Panoche FSL 
 
 18.8 
 
 54.3 
 
 73.1 
 
 0.78 
 
 2.89 
 
 3 
 
 67 
 
 KNO3 
 
 Lethent CI 
 
 17.4 
 
 47.9 
 
 65.3 
 
 0.76 
 
 1.51 
 
 2 
 
 28 
 
 Urea-S 
 
 Panoche FSL 
 
 8.9 
 
 38.4 
 
 47.3 
 
 3.75 
 
 9.78 
 
 13 
 
 53 
 
 (NH4)2S04 
 
 Oxalis C 
 
 24.5 
 
 38.2 
 
 52.7 
 
 1.60 
 
 1.45 
 
 3 
 
 05 
 
 *Applied fertilizer nitrogen 
 
 
 
 
 
 
 
 The percentage of recovery by grain sorghum of the applied fertilizer 
 nitrogen was greatest, 13.5 percent, in the Panoche fine sandy loam 
 treated with the sulfur coated urea. The large recovery rate in this 
 treatment was due to the great amount of residual N remaining in the 
 soil as a result of the slow release of N from sulfur coated urea. 
 The recovery rates in the other treatments ranged from 2.3 to 3.7 
 percent. 
 
 The percentages of the applied fertilizer nitrogen recovered by 
 barley, grain sorghum and in the water samples collected between 
 December 16, 1968 and August 18, 1969 are listed in Table 28. They 
 ranged from a maximum 80.6 percent in Panoche fine sandy loam treated 
 with KNO3 to a minimum of 61.4 percent in Panoche fine sandy loam 
 treated with sulfur coated urea. The recovery from the other systems 
 ranged from 66.3 to 59.8 percent. The high percentage recovery from 
 Panoche fine sandy loam soil treated with XNO3 was probably because 
 the NO3-N form of fertilizer is more mobile in the soil and thus a 
 greater root surface would be available to absorb the nitrogen. 
 
 These data do not account for a minimum of 19.4 and a maximum of 
 .38.5 percent of the applied fertilizer nitrogen. No analyses have 
 been made to determine the quantities that might be accounted for 
 by the following: (1) volatilization and denitrif ication, (2) tied 
 up in the plant roots, (3) adsorbed on the clay complex, (4) converted 
 -to an organic N form by soil bacteria, (5) remained in solution in 
 the soil columns. 
 
 A portion of the residual N could be leached from the columns at a 
 
 later date. To check this, water is still being applied to the columns 
 
 and the leachate collected, however, as this is written no additional 
 data are available. 
 
 (67) 
 
TABLE 28 
 
 Recovery of Applied Fertilizer Nitrogen in Barley, 
 Grain Sorghum, and Water Samples 
 
 Fertilizer 
 
 Soil 
 Type 
 
 Barley 
 
 Grain 
 Sorg-hum 
 
 Water 
 Samples 
 
 Total 
 
 
 
 % 
 
 ^ 
 
 % 
 
 % 
 
 (NH4)2S04 
 
 Panoche CL 
 
 65.6 
 
 2.87 
 
 0.30 
 
 SB. 17 
 
 KNO3 
 
 Panoche FSL 
 
 73.0 
 
 3.67 
 
 3.91 
 
 80.58 
 
 KNO3 
 
 Lethent CL 
 
 65.3 
 
 2,28 
 
 2.24 
 
 69.82 
 
 S:Urea-N 
 
 Panoche FSL 
 
 47.3 
 
 13.53 
 
 0.56 
 
 51.39 
 
 (NH4)2S04 
 
 Oxalis C 
 
 62.1 
 
 3.05 
 
 0.58 
 
 56.33 
 
 After the barley and grain sorghum crops were harvested, soil samples 
 were taken from one of each of the paired lysimeters. These samples 
 were analyzed for nitrate, organic N and amount of 15n. The results 
 of these tests for two of the lysimeters, one filled with Panoche 
 FSL to which NO3 fertilizer had been applied and one with Panoche 
 CI to which NH4 fertilizer had been added, are in Table 29. The 
 amounts of NO3-N remaining in the soils were small and relatively 
 consistent throughout the depths of the column. The two columns 
 had essentially the same concentration and distribution of NO3-N 
 indicating no difference as a result of the applications of different 
 types of fertilizers and soil textures. Only about 0.8 percent of 
 the applied fertilizer remained in the soil in the nitrate form. 
 
 The majority of the applied nitrogen still in the soil was in the 
 organic form and the largest amount of the l^N, representing the 
 applied nitrogen, remained in the top 15 centimeters of soil. This 
 was because the returned crop residue was concentrated in this depth. 
 The nitrogen fertilizer that remained in the organic fraction was 
 25.9 percent of that applied to the Panoche CL and 19.9 percent in 
 the Panoche FSL. 
 
 The amounts of -^^H collected from the various sampling categories 
 are listed in Table 30. These data show that an average of approxi- 
 mately 56 percent of the applied nitrogen was adsorbed up by the 
 plants. The greatest removal of fertilizer N by the crops was from 
 those lysimeters to which the nitrates were applied. There was no 
 significant difference between the recovery of nitrogen in those 
 lysimeters applied with NH4 and urea. The residual nitrogen in the 
 soil accounted for 13.1 to 30.5 percent or an average of about 24 
 percent of the applied nitrogen. The largest percentage of this 
 fraction was found in those columns to which the ammonium type 
 / fertilizer had been applied. The quantity of the applied nitrogen 
 ■> that was unaccounted for ranged from 12.4 to 24.5 percent. This 
 I amount, aside from any possible analytical error, was lost through 
 volatilization and denitrification. 
 
 (68) 
 
TABLE 29 
 
 Recovery of Applied Fertilizer Nitrogen in 
 Nitrogen Fraction from Two 
 
 the Nitrate and Organic 
 Lysimeters 
 
 Depth 
 
 Panoche CL (3) (NH4S0d) 
 
 Panoche FSL (6) (KNOg ) 
 
 cm 
 
 NO^-N 
 ppm 
 
 ppm 
 
 Organic N 
 
 -L^N mg 
 
 NO^-N 
 ppm 
 
 ppm 
 
 Organic N 
 -L^N mg 
 
 0-15 
 
 43 
 
 358 
 
 22.2 
 
 41 
 
 246 
 
 12.6 
 
 15-30 
 
 38 
 
 310 
 
 4.2 
 
 48 
 
 220 
 
 1.0 
 
 30-45 
 
 42 
 
 288 
 
 1.7 
 
 47 
 
 211 
 
 1.3 
 
 45-60 
 
 45 
 
 3 53 
 
 0.8 
 
 35 
 
 243 
 
 3.4 
 
 60-75 
 
 41 
 
 281 
 
 0.6 
 
 49 
 
 234 
 
 1.5 
 
 75-90 
 
 49 
 
 284 
 
 0.5 
 
 42 
 
 234 
 
 1.0 
 
 90-105 
 
 45 
 
 176 
 
 0.4 
 
 43 
 
 213 
 
 0.3 
 
 105-120 
 
 50 
 
 178 
 
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 (69) 
 
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 (70) 
 
The conditions in the lysimeters will be different than field con- 
 ditions. In the lysimeters, the root distribution is rather uniform 
 throughout the soil area while in the field, especially in row crops, 
 there would be areas between the rows where the root density is 
 relatively low. Under these conditions, unless special care is 
 taken in fertilizer placement, ie, in bands near the plant, and to 
 avoid excess irrigation there could be greater losses of fertilizer 
 nitrogen than indicated in the lysimeter studies. 
 
 Other lysimeter studies were conducted on the movement of nitrogen- 
 ous salts in unsaturated flows under non-cropped conditions. Cal- 
 cium nitrate and calcium chloride were applied to the columns and 
 four inches of water added every two weeks. Under the aerobic 
 conditions that existed in the upper portion of the column the N03's 
 and Cl's moved with the percolating water. However, under the ana- 
 erobic conditions in the lower saturated portion of the column the 
 nitrates were changed to a different form of N. Although part of 
 this nitrogen was probably changed to an organic form in the cell 
 material of microorganisms, most investigators attributed low re- 
 coveries primarily to denitrif ication (16). Chlorides, which are 
 not subject to change to gaseous form under these conditions, were 
 moved through the column with the percolating water and collected 
 in the leachate. The movements of the nitrates and chlorides in 
 one of the lysimeters are plotted in Figures 17 and 18. 
 
 It can also be noted from these data that approximately 36 inches 
 of applied water was required to move the chlorides through the six 
 foot soil column. The porosity of these soils is approximately 
 50 percent, therefore, the equivalent of about one pore volume of 
 water moved the nitrate and chloride front through the columns. 
 
 A nitrogen balance sheet was prepared on one lysimeter to gain some 
 insight on nitrogen gains and losses that occurred. The budget 
 was prepared on lysimeter number 6 which was filled with Panoche 
 fine sandy loam soil and treated with KNOv. The measurements were 
 made over approximately a years time, from December 13, 1968 to 
 December 20, 1969, during which one fertilizer application was made 
 and two crops, one of barley and one of milo, were grown and harvested. 
 
 The sources of nitrate -nitrogen available were the applied fertilizer, 
 irrigation water, the residual nitrate in the soil at the start of 
 the study and the nitrogen available as the result of mineralization 
 of the organic nitrogen. One application of 1.27 grams of KNO3 
 fertilizer which was equivalent to 100 pounds of nitrogen per acre, 
 was added to the soil. The applied irrigation water, which con- 
 tained about 0.5 parts per million of nitrate -N, added 0.09 grams 
 of nitrogen or the equivalent of about 7 pounds per acre. The 
 residual nitrate in the soil column at the start of the study was 
 calculated to be 1.05 grams or equivalent of 83 pounds per acre. 
 These three sources totaled 2.42 grams or equivalent to 190 pounds 
 of nitrate -N per acre . 
 
 (71) 
 

 
 
 
 LEACHATE (1) 
 "A" DEPTH - 1.70' 
 B -2.73' 
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 ITRATES IN "d" depth a LEACHATE REMAINED 
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The losses were due to the removal of nitrogen by the crops, 
 removal in the leachate, removal through sampling of the suction 
 probes, and the unaccounted for losses to be primarily the 
 result of denitrification and volatilization reactions. The amount 
 removed by the barley and milo crops was 2.90 grams or the equivalent 
 of 225 pounds per acre. A calculated 0.55 grams, the equivalent 
 of 43 pounds per acre, was removed in the leachate and 0.12 grams, 
 or 9 pounds per acre, was removed by the suction probes for sampling 
 purposes. There was an unaccounted for loss of 14.6 percent of the 
 applied fertilizer which was 0.15 grraras or 12 pounds per acre. The 
 causes of these losses were not documented but it is postulated 
 that the major cause was denitrification and a minor cause was 
 volatilization of nitrogen compounds. There were undoubtedly some 
 similar losses from the other sources of nitrates but this was not 
 proven, therefore, no values were assigned to them. The total 
 losses of nitrogen from all factors amounted to 3.7 grams or an 
 equivalent of 290 pounds per acre. 
 
 In addition to the losses, in order to balance the system, the 
 nitrates that remained in the soil column at the end of the study 
 must be accounted for. These were measured to be 0.55 grams or 43 
 pounds per acre. The losses plus these residual nitrates totaled 
 4.27 grams or 333 pounds per acre. This amount compared to the 
 measured contributions of 2.42 grams or 190 pounds per acre gives 
 a difference of 1.85 grams or 143 pounds per acre. It was assumed 
 that mineralization of the organic nitrogen compounds in the soil 
 was the major source of nitrates that made up this difference of 
 143 pounds per acre. This amount is somewhat larger that much of 
 the data cited in the literature. It indicates the large reserve 
 of potential nitrates that are in most soils in the insoluble 
 organic forms. 
 
 The assumption was made for this study that nitrate -N is the only 
 soluble nitrogen form in the soil and water. The measurements 
 indicated that although there were small amounts of ammonia and 
 nitrite the quantities would be insignificant in the overall balance. 
 
 A summary of the nitrogen balance is in Table 31. 
 
 Sources of Nitrogen to the Drain 
 
 The nitrogen that occurs in the drain effluent originates from three 
 major sources: (1) those sources that are native to the area or 
 occur naturally, (2) those that occur as a result of agricultural 
 activities and (3) those that occur from municipal and industrial 
 waste products. 
 
 The major source of native nitrogen to the drain will be that which 
 occurs naturally in the soils and substrata or the soil profile. 
 There may be small quantities of ammonia and nitrate present in 
 the drainage water but for all practical purposes the nitrogen that 
 
 (74) 
 
Table 31 
 
 Nitrogen Balance Sheet - Lysimeter #6 
 
 Item 
 
 Contribution 
 
 Residaul NO3-N (start) 
 Applied Fertilizer Nitrogen 
 Applied in Water 
 Mineralization 
 
 Total 
 
 Removal 
 
 Crop (barley and milo) 
 Leachate 
 Suction Probe 
 Unaccounted for Losses 
 
 Total 
 
 Residual NO3-N (end) 
 
 Total Removal & Residual 
 
 Nitrogen 
 
 gms 
 
 1.06 
 
 1.27 
 
 .09 
 
 1.85 
 
 4.27 
 
 2.90 
 .55 
 .12 
 .15 
 
 3.72 
 
 .55 
 4.27 
 
 Ibs/AC 
 
 83 
 
 100 
 
 7 
 
 143 
 
 333 
 
 226 
 
 43 
 
 9 
 
 12 
 
 290 
 
 43 
 
 333 
 
 moves to the drain will be in the nitrate form. Nitrates are soluble 
 and readily moved with the percolating waters. If they are not 
 intercepted by the plant roots or reduced to a volatile gas, usually 
 molecular nitrogen and/or nitrous oxide, they will eventually appear 
 in the groundwater or drainage effluent. The ammonia in the soil 
 is normally adsorbed by the soil base exchcmge mechanism and will 
 not move with the water. 
 
 The largest quantity of nitrogen in the soils is in organic forms. 
 Although these forms are generally inert, mineralization takes place 
 through a three step process which converts organic N to nitrate by 
 bacterial activity. The bacteria are obligate aerobes which require 
 molecular oxygen to produce nitrates therefore maximum nitrification 
 will take place in the plow zone of the soil. Nitrification will 
 decrease with soil depth and in areas of high water table usually^ 
 no nitrates will be formed. Studies indicate (19) that 40 to 80 "^ 
 pounds of nitrogen as nitrates may be produced each year in the top^ 
 five feet of soil by this process. 
 
 Data from the transect study indicated that the average quantity of 
 nitrate in the 0-5 foot depth of soil was 258 pounds per acre. The 
 
 (75) 
 
rate that this nitrate will be moved to the drain is subject to 
 much speculation. Under the most favorable conditions, that is 
 complete piston flow displacement, within about five years nitrates 
 in the top five feet of soil im.mediately above the drains would be 
 leached. This estimate was based on a pore volume of six inches 
 per foot or 2.5 feet for the five foot solid profile and the 
 estimated drainage effluent of six inches per acre per year. However, 
 from field experience and laboratory investigations, it is known 
 that complete displacement does not occur. There is diffusion by 
 the salts into the smaller pores where they are isolated from the 
 percolating water moving through the larger pores. Also under 
 cropped conditions evapotranspiration removes the moisture from 
 the upper soils thereby creating a moisture gradient upward and 
 reversing the direction of the water and salt movement. 
 
 Other factors that will influence the length of time it will take 
 the nitrates to reach the drain are the drain spacing, the depth 
 of the drain, depth of soil barrier, and the hydraulic conductivity 
 of the soils. 
 
 Estimates of the nitrogen contributions of each of the various 
 sources were developed in the section on the nitrogen budget analysis. 
 The values are listed in Tables 1 through 7. The analyses show that 
 on an overall basis the nitrogen added to the soil by fertilizers, 
 irrigation water, rainfall, stream flow, leguminous plants, animal 
 and municipal wastes were essentially in balance with the nitrogen 
 removed by the harvested crops and volatilization of nitrogen gases. 
 Regardless of the source of the nitrogen taken up by the plant, 
 whether from sources outside the soil or from the residual nitrogen 
 in the soil, the same amount of nitrogen would be available to be 
 leached to the drains. 
 
 It is obvious that where the nitrogen contributions are not evenly 
 distributed throughout the area, such as cattle, municipal and 
 industrial wastes, only a small part of the nitrogen from these 
 sources will be used by the crops. As a result a larger percentage 
 of this nitrogen could be leached to the drains. 
 
 The beef cattle operations now are concentrated in three feed lots 
 in an area of about 500 acres. Much of the waste from these lots 
 will be removed as manure and spread throughout the district and a 
 lesser amount will be lost by volatilization. The remainder could 
 be a source of the nitrogen in the drainage water. The amount of 
 nitrogen from this source that reaches the groundwater will vary 
 with the conditions present, such as rainfall, soil conditions, and 
 surface drainage. Although no specific studies were conducted in 
 this area, other studies give some indications of the relative amounts 
 of nitrate moving through soil profiles toward the groundwater. The 
 contributions of nitrogen from concentrated livestock feeding operations; 
 were studied in the South Platte River Valley in Colorado (20). The 
 average total nitrate-nitrogen to a depth of 20 feet in the soil 
 
 f76^ 
 
profile averaged 1,435 pounds per acre as determined from 47 core 
 samples. There was a great variability in these samples, ranging 
 from almost none to more than 5,000 pounds per acre. Also the water 
 samples collected from under the feed lots had a greater concen- 
 tration of ammonium -N than those sampled from irrigated croplands. 
 The feedlot samples averaged about 4.5 ppm and the irrigated field 
 samples averaged only about 0.2 ppm. 
 
 The rainfall in the area cited above is about double that of the 
 San Luis area. Undoubtedly there would be less movement of nitrogen 
 here but some areas near feed lots probably will have unusually 
 high nitrogen concentrations in the drains. 
 
 In a like manner, the areas adjacent to the municipal sewage disposal 
 systems would have large quantities of nitrate leached into a small 
 area. The drains serving these areas would have unusually high 
 nitrate concentrations in the effluent unless some remedial actions 
 are taken to either transport them to other areas or install treat- 
 ment processes to remove the nitrogen before it reaches the ground- 
 water. 
 
 Quantity of Nitrates in the Drainage Effluent 
 
 The existing drains on the lands adjacent to the study area were 
 monitored at various times by the State of California Department 
 of Water Resources and the University of California at Los Angeles 
 to determine the quantity and seasonal distribution of the nitrate 
 concentration in the drainage effluent. In the San Luis area where 
 no drains have been installed, the nitrate concentrations were 
 calculated from the Prediction Model developed by the University 
 of Arizona and the Bureau of Reclajnation Engineering and Research 
 Center. 
 
 The data from the drains monitored in the San Joaquin Valley in- 
 dicated a range of NO3-N in the effluents from 2 to 400 milligrams 
 per liter (21). The annual flow weighted average of these drains 
 measured during 1956-1969 period was 19.3 mg/1. During the period 
 for which data are available, there was no evidence that there has 
 been any significant reduction in the average annual nitrate concen- 
 trations in the drainage effluent. 
 
 Anticipated Changes in Nitrogen Sources 
 
 Fertilizer Usage 
 
 The usage of fertilizer is expected to increase in the future how- 
 ever the rate of the increase is subject to speculation. Interviews 
 with Agricultural Extension Specialists indicate that they anticipate 
 little increase in the per acre applications on the various crops 
 in the foreseeable future. This prediction is based upon two major 
 premises: (1) The rates now used appear to be an optimum balance 
 between costs and economic return and (2) The present emphasis on 
 
 (77) 
 
ecology and conservation will exert public pressure on the farming 
 community to prevent increased use of commercial fertilizers. 
 
 There will be changes in the cropping pattern toward more intensive 
 farming, the production of crops that require higher fertilizer 
 application, more double cropping and the development of the areas 
 which are now non-irrigated. These changes will increase the amount 
 of fertilizer that will be applied under ultimate development from 
 the 1958 average application of about 60 pounds per acre to an 
 estimated 87 pounds per acre. For the total area this would amount 
 to an increase from about 20,120 tons to 29,200 tons annually. 
 
 Future Crop Pattern 
 
 Before supplemental surface water was available, the farmers were 
 forced to adjust their crop patterns to accommodate a deficient 
 water supply. Generally, this was accomplished by planting low 
 water requirement crops, winter crops and allowing some land to lay 
 idle or undeveloped. As water from the San Luis Project becomes 
 available, the operator will be able to grow the crops which are 
 most economically feasible or that best fit his farming program. 
 
 The major change in the crop pattern is expected to be the reduc- 
 tion in the acreage of barley and increases in alfalfa seed, vege- 
 tables and deciduous fruits and nuts. There is also expected to 
 be an increase in the number of acres double cropped. It is projected 
 that the lands which have not been developed for irrigation or have 
 been left idle will be prepared for cultivation and for the most 
 part will be irrigated each year. 
 
 Cattle production is expected to increase about in proportion to 
 the increase in the human population. This production will be, 
 as it is now, primarily a feed lot operation. This type of operation 
 will continue to concentrate the nitrogen waste in relatively small 
 areas and create local hot spots which could introduce high nitrate 
 concentration to the drains servicing these areas. 
 
 Sheep production in the area is based primarily in grazing off the 
 crop residues. Barley stubble has been the major pasture source; 
 however, with the more intensive farming practices anticipated in 
 the future, the acreage of this crop will be cut drastically. As 
 a result, it is expected that the number of sheep will drop cor- 
 respondingly. The resultant total nitrogen waste from both sheep 
 and cattle will probably not increase appreciably over present levels. 
 
 Leaching Native Nitrogen 
 
 As explained in an earlier section, theoretically, the soluble 
 nitrogen could be leached from the top five feet of soils in a 
 minimum of five years, however, in actual practice it would undoubt- 
 edly be much longer. Also it could take many years to move that 
 nitrogen that has been leached down into the subsoil near the mid- 
 point of the drain spacings to the drains. The time required will 
 
 (78) 
 
depend primarily upon the drain spacing, the volume of leachate , 
 the hydraulic conductivity of the soils, and the depth of the sweep 
 of the flow lines. This leaching time might be reduced by decreasing 
 the length and depth of the flow lines by decreasing the drain 
 spacing and depth. 
 
 The study that monitored nutrients from tile drainage systems (21) 
 found that nitrates are not removed at as fast a rate as chlorides. 
 This would indicate that there is a continuous replacement of nitrates 
 in the system. The source of this replacement could be the applied 
 nitrogen, primarily fertilizer, or from the organic nitrogen in the 
 soil. The analyses of the transect samples show that there is a 
 very large reservoir of residual organic nitrogen, a portion of which 
 under favorable environmental conditions can be mineralized to nitrates. 
 The rate that this organic nitrogen will be mineralized will depend 
 upon the amount of the material present in the soil, the C:N ratio 
 and environmental factors such as amount of aeration, moisture and 
 temperature. The water quality systems model being developed in 
 connection with these studies are expected to give some insight on 
 the rate and the change in quantity over time of the nitrate miner- 
 alization under the various conditions present in the area. 
 
 Increase in Municipal and Industrial Water 
 
 Some demographers predict (23) that this area will become absorbed 
 in a megalopolis (a sprawling population belt in which once clearly 
 defined urban areas tend to blend into each other) that will cover 
 most of Central and Southern California. This may occur at some 
 very distant time, but for the foreseeable future no extreme change 
 from the present rural pattern of relatively large farm operations 
 and small towns is anticipated. 
 
 The importation of an adequate irrigation water supply which will 
 permit more intensive farming and the construction of the north- 
 south interstate highway through the area will give some impetus 
 to a population growth; however, this will be offset by the increased 
 mechanization of farm work and the resultant reduced demand for 
 farm laborers. 
 
 If it is assumed that the population growth of the area continues 
 at the same rate as the past ten years, although nationally the rate 
 is expected to decrease, the population is estimated to reach about 
 2 5,000 inhabitants by 2010. 
 
 The improved transportation facilities available as the result of 
 construction of the interstate highway will attract a number of new 
 and different industries into the area but it is anticipated that 
 the industry of the area will continue to be agriculturally oriented. 
 It is estimated that they will increase somewhat more rapidly than 
 the total population because of the increased requirements for 
 mechanized equipment and services as a result of the greater farm 
 iinechanization. 
 
 (79) 
 
The increased population and industrial growth will about double 
 the waste-nitrogen disposal requirement for the area to approximately 
 174 tons. This amount will be spread over about twice the area; 
 therefore, the per acre application rate will remain about the same 
 as the present 53 pounds per acre. The drainage effluent near the 
 feedlots and population centers may be high in nitrates unless some 
 corrective action is taken to remove them. 
 
 Control of Nitrogen at the Source 
 
 The principal means of controlling the quantity of nitrogen that 
 reaches the drains is by reducing the amounts of applied nitrogen, 
 primarily fertilizers, and native nitrogen that are leached through 
 the soils. These sources can best be controlled by educational 
 programs to advise and encourage the most efficient farming prac- 
 tices and by the installation of specially designed farm drain systems. 
 
 Farm Advisory Program 
 
 The lysimeter studies show that under normal soil conditions and 
 good irrigation management practices, very little applied fertilizer 
 nitrogen reached the drain. However, in actual farm practices where 
 the soils, crop, root pattern and cultural practices vary greatly, 
 a greater percentage of this applied nitrogen could possibly move 
 to the drain. 
 
 An advisory program conducted by the Agricultural Extension Service 
 and other agencies should be encouraged to advise growers on cul- 
 tural practices that would reduce the amount of nitrogen that moves 
 through the soil profile to the drains. The areas in which these 
 agencies might give assistance to the farmers could include: 
 
 Soil Management ; Although most of the soils in this area are 
 medium to fine textured there are sizeable areas of light textured 
 soils on the south end of the district. It is especially important 
 that these light soils are managed properly to prevent excess leach- 
 ing. Practices which could be encouraged to reduce losses might 
 include matching of crops to soil conditions. Studies (20) have 
 shown that fields of deep rooted crops such as alfalfa have practi- 
 cally no nitrates below them. An alfalfa crop in rotation with 
 shallow rooted crops possibly would prevent much of the nitrate 
 leached below the root zone of shallow rooted crops from reaching 
 the water table. 
 
 Fertilizer Management : Some types of fertilizers, especially 
 the nitrate forms, are fast release types which may be leached 
 fairly rapidly through the soil. Other types such as ammonia forms 
 which are absorbed by the negatively charged ions in the clay part- 
 icles and specially treated urea forms which dissolve slowly in 
 the soil are less rapidly leached. The effect of the rate of 
 release on the amount of nitrogen leached would be especially sign- 
 ificant in the light textured soils. Other factors which would 
 
 (80) 
 
influence the rate of movement of the nitrate through the soils 
 are the amount, time and placement of the fertilizer. Under con- 
 ditions of rapid nitrogen movement it would be better to make a 
 larger number of smaller fertilizer applications than one large 
 application. Also there would be less losses if the fertilizers 
 were placed in bands near the areas of greatest root density rather 
 than being broadcast uniformly over the field. 
 
 Water Management : Nitrate -nitrogen generally will move with 
 the percolating water. Irrigation applications should be adjusted 
 to avoid excess deep percolation and the resultant loss of nitrogen. 
 Only enough water should be applied to meet the evapo-transpiration 
 requirements of the crops and have adequate deep percolation to 
 prevent a buildup of salts in the root zone. 
 
 Crop Management : Various crops have different nitrogen require- 
 ments and, as mentioned above, different root depths which influence 
 nitrogen utilization. The amount of nitrogen leached to the drains 
 might be reduced by growing the high nitrogen requirement plants 
 on the fine textured soils. 
 
 Specially Designed Farm Drain Systems 
 
 Once the residual or applied nitrogen has moved below the root zone 
 of the plant, the only means to reduce the amount that will reach 
 the drain is by denitrif ication or by reducing the area that con- 
 tributes to the drain. 
 
 Laboratory studies (17) have shown that denitrif ication, the reduc- 
 tion of nitrates to nitrogen gas which is dissipated to the atmos- 
 phere, can take place in soils, therefore, under proper conditions 
 it should occur in the field. The process normally takes place in 
 the saturated soil near or at the water table as a result of the 
 action of anaerobic bacteria. Willardson, et al (23) are conducting 
 studies to determine if, when the drain lines are submerged contin- 
 uously and an organic energy source present, there is a reduction 
 in the nitrate concentration of the effluent. If these results 
 prove positive, recommendations should be made that farm drains be 
 designed to maintain submerged conditions to encourage denitrif ication. 
 
 The quantity of nitrates in the soils and substrata which can be 
 leached to the drains is directly proportional to the depth of the 
 area swept by the drainage flow lines. Any action which will reduce 
 the depth of the flow line will reduce the ultimate quantities of 
 nitrate in the drain. The most feasible methods to do this is to 
 decrease the drain tile depths and spacings. 
 
 (81) 
 
SECTION VI 
 REFERENCES 
 
 1. Tisdale, Samuel L. and Nelson, W. L., Soil Fertility and Fer- 
 tilizers, 2nd Edition, Macmillan Co., New York, N. Y. , 1966. 
 
 2. Stout, Perry R. and Burau , R. G., "The Extent and Significance 
 of Fertilizer Build Up In Soils as Revealed by Vertical Dis- 
 tribution of Nitrogenous Matter Between Soils and Underlying 
 Water Reservoirs. 
 
 3. Doneen, L. D., A Study of Nitrate and Mineral Constituents 
 from Tile Drainage in the San Joaquin Valley, California, A 
 Report to the Central Pacific River Basin Project, FWPCA, 
 November 1966. 
 
 4. Terman, G. L. , Volatilization Loss of Nitrogen as Ammonia from 
 Surface Applied Fertilizers, Agrichemical West, December 1965. 
 
 5. Martin, J. P. and Chapman, H. D., Volatilization of Ammonia 
 from Surface-Fertilized Soils, Soil Science Soc, Vol. 71, 1951. 
 
 5. Harding, R. B., Embleton, T. W. , Jones, W. W. , Leaching and 
 
 Gaseous Losses from Some Nontilled California Soils, California 
 Citrograph, July 1963. 
 
 7. Junge, Christian E., The Distribution of Ammonia and Nitrate 
 in Rain Water Over the United States; Transactions, American 
 Geophysical Union, Vol. 19, No. 2, April 1958. 
 
 8. Gambell, Arlo W. and Fisher, D. W., Occurrence of Sulfate and 
 Nitrate in Rainfall, Journal of Geophysical Research, October 
 15, 1954. 
 
 9. USDI, Geologic Survey, Description and Chemical Analyses for 
 Selected Wells in the Dos Palos-Kettleman City Area, San Joaquin 
 Valley, California, Menlo Park, California, 1969. 
 
 10. USDI, Bureau of Reclamation, Geology Branch, Nitrate Analyses 
 from Wells and USBR. Geohydrologic Observation Holes in the 
 
 San Luis Unit and Mendota-Firebaugh Areas. Sacramento, California, 
 December 1969. 
 
 11. Bartholomew, W. V. and Clark, F. E., Soil Nitrogen No. 10, 
 Agronomy Series, Amer. Soc. Agron. 1965. 
 
 12. Erdman, L. W., Legume Innoculation, What It Is - What It Does, 
 USDA Farmers Bull. 2003, 1959. 
 
 (82) 
 
13. Loehr, Raymond C, Animal Wastes - A National Problem, Journal 
 of the Sanitary Engineer Div. , April 1969. 
 
 14. Morrison, Frank B., Feeds and Feeding, 21st Edition, the Mor- 
 rison Publishing Co., Ithica, N. Y. 1948. 
 
 15. Reclamation Instructions, Release No. 577-1, U. S. Department 
 of the Interior, Bureau of Reclamation, Office of the Chief 
 Engineer, Denver, Colorado, 1957. 
 
 16. Allison, F. E., The Fate of Nitrogen Applied to Soil, Advances 
 in Agronomy, Vol. 18, 1966, American Soc. of Agronomy. 
 
 17. Meek, B. D. , Grass, L. B., and MacKenzie, A. J., Applied 
 Nitrogen Losses in Relation to Oxygen Status of Soil, Soil 
 Sci. Soc. Proceedings, Vol. 33, No. 4, July-August 1969. 
 
 18. Stanford, G., England, C. B. and Taylor, A. W. , Fertilizer Use 
 and Water Quality, USDA, ARS 41-168, October 1970. 
 
 19. Allison, F. E. , Porter, J. N., and Sterling, L. D., The Effects 
 of Partial Pressures of O2 on Denitrif ication in Soil - Soil 
 Science Society of America Proceedings - 24, 283, 1960. 
 
 20. Stewart, B. A., Viets, F. G., Jr., Hutchinson, G. L. , Kemper, 
 W. D., Clark, F. F. , Fairbourn, M. L. and Strauch, F. , 1967. 
 Distribution of Nitrate and Other Pollutants Under Fields and 
 Corrals in the Middle South Platte Valley of Colorado, ARS 
 41-134, U.S. Dept. of Agric. , Washington, D. C. 
 
 21. Nutrients From Tile Drainage Systems, Calif. Department of Water 
 Resources, Agricultural Wastewater Studies Group, San Joaquin 
 Valley, California, December 1970. 
 
 22. The Evolution of a Super-Urban Nation, Business Week, October 
 17, 1970. 
 
 23. Willardson, L. S., Meek, B. D., Grass, L. B., Dickey, G. L. , 
 and Bailey, J. W., Drain Installation for Nitrate Reduction, 
 paper presented at ASAE Winter meeting 1969. 
 
 ft v. S. GOVERNMENT PRINTING OFFICE :1 973 — 51 U-1 5lt/27'l 
 
 (83) 
 
Accession /Vi/mfccr 
 
 w 
 
 SiihjccI Field Sc Croup 
 
 05B, 05G 
 
 Department of the Interior 
 Bureau of Reclaraatlon 
 Fresno Field Division 
 Fresno. California 93721 
 
 SELECTED V/ATER RESOURCES ABSTRACVS 
 INPUT TRANSACTION FORM 
 
 , I Organic 
 
 Possibility of Reducing Nitrogen in Drainage Water By On Farm Practices 
 
 IQ Author^s) 
 
 Williford, John W. 
 Cardon, Doyle R. 
 
 1/ Project Designation 
 
 13030 ELY 
 
 21 
 
 22 
 
 Agricultural Wastewater Studies, 1971 
 
 Report No. REC-R2-71-11 
 
 Pages 83 Figures 18 Tables 31 Reference 23 
 
 23 
 
 Descriptors (Starred Fust) ^jjj^^rates, *Agricultur al waste, *Fertilizers , Lysimeters, 
 Sub-surface drainage. Denitrification, Ammonia, Crop production. Animal wastes, 
 Municipal wastes 
 
 25 I Identifiers (Starred Fii 
 
 *San Luis Service Area, California, *Nitrogen Budget, 
 Mineralization, Organic Nitrogen 
 
 27 ^^^"•'^' f^ nitrogen balance study of the San Luis Service Area determined that the 
 
 average annual nitrogen contributions from all sources other than residual soil 
 nitrogen were approximately equal to the nitrogen removal by crops and gaseous losses. 
 This would indicate that, although in many instances the residual-nitrates would replace 
 some of the contributed nitrogen, especially fertilizers, animal and municipal wastes, 
 the amount of nitrates moved to the drains would be proportional to the amounts of 
 soluble, native nitrates in the soil. 
 
 A soil sampling study at several sites throughout the area indicated that there were 
 a wide range in the concentrations of nitrates, ammonia and organic nitrogen in the soils 
 and subsoil. There were extremely high concentrations of nitrates in those soils located 
 on the interfan positions between the larger streams. 
 
 Fertilizer studies in lysimeters shows that in medium to heavy textured soils under 
 normal irrigation and fertilizer management practices very little nitrogen is leached to 
 the drains. Nitrate type fertilizer contributed more nitrogen to the drainage effluent 
 than ammonia and slow release sulfur coated urea fertilizers. 
 
 It was concluded that the best possibilities to reduce nitrogen in drains by on farm 
 practices will be to establish Farm Advisory Programs to encourage the most efficient farm 
 management and fertilizer practices and to design drain systems to promote denitrification 
 and reduce the area swept by the drain flow lines. 
 
 Abstfjctcr 
 
 John W. Williford 
 
 In-liiuiion 
 
 U. S. Bureau of Reclamation 
 
 :STJSCE5 SC'E-1 7 
 ,R T-.ICST OF T«e 1 
 OW O. C. 2CJ40 
 
:leat 
 
 WATER POLLUTION CONTROL RESEARCH SERIES • 13030 ELY 05/71-12 
 
 REC-R2-ri-l2 
 DWR NO. I7A- IB 
 
 BIO-ENGINEERING ASPECTS OF AGRICULTURAL DRAINAGE 
 SAN JOAQUIN VALLEY, CALIFORN lA 
 
 JUN 5 1975' 
 MAY 2 7 REC'D 
 
 SALINATION OF AGRICULTURAL TILE DRAINAGE 
 
 ■ffSSth^-nf^iimMa* 
 
 MAY 1 97- I 
 
 ^m 
 
 UNIVERSITY OF CALIFORNIA 
 DAVIS 
 
 VIRONMENTAL PROTECTION AGENCY»R ESEARCH AND MONITORING 
 
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