... ; -...,y,^:-.:,.^ S ^,-,,,^^ : , r: , n:: _ ..^ : MANAGING IRRIGATED PETERSON • OSTERLI • BERRY *W >"»» << 4 <. V £j! s^\ Figures from California Field Crop Statistics published 2 by California Crop and Livestock Reporting Service. Acreage figures do not include irrigated mountain meadows, Sudangrass, or alfalfa stands which are pastured. COSTS are highest for grading, but proper land preparation reduces future expense for water and weed control Overhead (per acre) Cost Life expectancy Depreciation Interest Land Grading Fences Irrigation preparation (land plane, check, field ditch) Turnout gates Stock water facilities Pasture stand Tillage equipment (based on 80 acres) Tractor Mower Pickup or auto Misc. shovels, small tools $200 . 00 75 00 15 00 14.00 2.50 2.50 20.00 25.00 4.00 20.00 2 00 $380 00 years 20 7 10 20 7 10 10 10 9 75 2 00 25 0.12 2 86 2 50 0.40 2 00 22 $11.10 Total. $10.00 3.75 0.38 0.35 06 0.06 0.50 0.60 0.10 50 05 $16.35 $27.45 Annual Cultural Cost (per acre) (not including water) * Cash and labor costs : Irrigate 16 times @ X A hr. labor $ 8 . 00 Fertilize : 50 lbs. P 2 5 $5.00 60 lbs. nitrogen 9 00 Application, 1/3 hr . 50 Mow 3 times @ }/% hr Ditch work and fence repair Misc. labor and truck use Taxes, $60.00 @ $5.75 3.00 1.00 1.00 3.45 Total cash and labor $16 . 45 Overhead 27 . 45 Total cost (not including water or fertilizer) $43 . 90 * Irrigated pasture will normally require from 2 X A to 4J^ acre-feet of water per year. Water costs vary widely, ranging from as low as $1.50 to more than $8 per acre-foot. MANAGING IRRIGATED PASTURES M. L. PETERSON V. P. OSTERLI L J. BERRY Land Preparation (Ordinarily, complete engineering costs will range from $4 to $6 per acre.) Irrigated pastures occupy land for longer periods than do most other field ffffCIClf loll crops. For this reason, grading, con- struction of levees, and proper drainage Manage irrigation to maintain a con- facilities are very important. The objec- tlnuous ^PP^ of readll y available mois- tives are to keep use of water and of ture ln the solJ at a11 tlmes to P ermit labor for irrigation to a minimum, and optimum plant growth with the least to insure high yields for the life of the amount of waste in water ' SGl1 ' and stand. (For more complete discussion, labor. The method of irrigation used will see University of California Circular be determined by permeability of the 43g \ soil, rate of water delivery, surface drain- Land grading to rigid specifications, a § e conditions, water costs, and by what while expensive, is the most important ls common practice for the area, operation in establishing an irrigated y^e border method pasture. Proper land preparation will • .1 . • i i i w-u *u- * ^ tp r • • is the most widely used. With this system, greatly reduce future costs of irrigation the strj of ]an( j between , he adjacent and weed control. Cost ol preparing land 1 n u a • a, a- . n , . . r levees usually have a grade m the direc- tor nood-irrigation 01 pastures ranges .- p • • .• r 1 . t t Q A f #iqa it a a tlon 0± irn g atlon ' ranging from about from $30 to $130 per acre. Underground QJ foQt tQ QA foot for each lQQ ^ of concrete pipelines conserve water and 1 .1 j n i c x i , , r f , , ,. . length, and not over 0.15 loot cross slope, save labor better than do open ditches, T r i «i j • . . . . , Vi e n ln cases ol poor internal soil drainage, but initial costs are greater. Ihe lollow- i p A £ inn £ 1 u r -i ii 1 * • i 1 a slope ol O.o loot per 100 leet should ing ngures, compiled by the Agricultural 1 -, . -a £ a - r- . c ' 1 • be used to provide surface drainage. Extension Service, show approximate r™ 1 ., -, .-,., ? u , , -, r 1 , rr Ihe length and width ol checks de- costs ior new pasture development on -, u. *i * u a 1 * . , , , r . ~ r . TT . pend upon the soil type, head ol water several hundred acres in a Central Val- -i 11 j + u 1 • +u a- *.• available, and the slope in the direction of irrigation. Length may range from a COST PER ACRE few hundred feet up to ft hfllf ^ but l m l eymg $ „ 2? should be limited to a distance that will w ell 9.50 . r . , . r tip Pipeline 24 50 insure lairly unilorm depth ol water Grading, including drainage penetration for the entire check. The facilities 54.50 width may range from 12 to 100 feet. " ump 25 - 50 Border checks present the fewest diffl- Total $118.00 culties in establishing fence lines for the [5] rotation grazing system. A levee 3 feet wide at the base and 6 inches high when settled will grow feed. Contour checks may prove most economical if the ground surface is relatively flat. This system requires either a large flow of water or a soil with a slow infiltration rate. Levees should have a settled height of 12 to 14 inches, and a base width of about 60 inches to withstand the tram- pling of stock. The contour system has many disadvantages: cross fencing for control of grazing is difficult; drainage limitations create a tendency to plant scalding; and weeds and mosquitoes are troublesome. As a result, many growers have changed from contour to border checks when possible. Sprinkler irrigation has special advantages where the water supply is scarce or expensive, the soil shallow or sandy, or the surface too rough or steep for economical leveling. The decision of whether to sprinkle or flood irrigate should be based upon eco- nomic considerations which may differ with each situation. Sprinklers are diffi- cult to manage in areas subject to strong winds. Wild flooding is used in rough, mountainous terrain where grading is impractical. This method requires very little grading or ditch preparation. Water is distributed from grade ditches located on ridges or along the sides of hills. The water is re- leased from the ditches at selected points, and moves down the side of the hill to the next distribution ditch. The waste of water resulting from this inefficient ap- plication method may be offset by the low initial cost and the minimum labor required. Successful irrigation by wild flooding requires the services of a careful operator when establishing the system. Water measurement A knowledge of the amount of water to apply to each field is essential for de- signing an irrigation layout. The most commonly used units of water measure- ment are: gallons per minute, cubic feet per second, and the miner's inch. The formulas at the bottom of the page may be used to compute the approximate depth of water applied to a field. The following "rules of thumb" are also convenient methods of estimating the irrigation potential of a given flow of water : One miner's inch (about ll 1 ^ gallons per minute) will put 0.6 inch of water on 1 acre or 3 inches on % acre m 24 hours; 1 cubic foot per second, or 450 gallons per minute, will put 2 feet of water on 1 acre in 24 hours or will supply a 9-inch depth of water for 80 acres in 30 days; 5 gallons per minute will irri- gate 1 acre by sprinkling, while 10 gal- lons per minute for each acre are desir- able when irrigating by flooding. Larger delivery rates permit more efficient use of labor with surface irri- gation. A delivery of 1,000 gallons per minute will adequately irrigate 100 acres, even at peak summer requirements. Most irrigated pastures will require irrigation at about 10- to 14-day intervals. If the irrigation is to be done by sprinkling, a sprinkler system can be designed that Cubic feet per second x hours Acre Gallons per minute x hours 450 x acres Miner's inches x hours = acre-inches per acre, or average depth in inches acre-inches per acre, or average depth in inches 40 x acres acre-inches per acre, or average depth in inches [6] Contour irrigation requires a large flow of water and a soil with a slow infiltration rate. Cross- fencing for control of grazing is more difficult with this system. Sprinkler irrigation is used where rate of water delivery is too small for surface methods or where the soil is too shallow or sandy, the land surface too rough and steep to make land grading desirable or economical. It is possible to apply water to any pasture by this method, which is practical so long as it proves economical. [7] will provide the exact amount of water required for correct irrigation within the desired irrigation intervals. Where strip checks or contour checks are used, the volume of water must be sufficient to cover the checks rapidly enough to pro- vide uniform distribution over the entire area. Water use and frequency of irrigation The depth of water applied and the fre- quency of irrigation depend upon the rate at which the crop uses water, the root depth of the crop, and the water- holding capacity of the soil. The amount of water necessary to penetrate to a depth of 1 foot when the soil is at the wilting point varies with the soil type. As a useful guide, 1 inch of water will wet a clay soil to a depth of 4 to 5 inches; a loam soil, 6 to 10 inches; and a sandy soil, 12 inches or more. The daily peak water use by an irri- gated pasture ranges from 0.25 to 0.35 inch per day, for interior valley condi- tions; and from 0.10 to 0.25 inch per day under coastal and semicoastal con- ditions. Ladino clover, with a daily peak use of 0.30 inch, will use 3 inches of water in 10 days. This amounts to nearly all of the available water in the top 2 feet of a loam soil. Therefore, Ladino clover, with its shallow root system, needs fre- quent light irrigations. The seasonal re- quirement will be from 2% to 4% acre- feet per acre. On medium-textured, well-drained soils, plants can remove moisture readily to the following approximate depths: FEET Ladino clover 2 Trefoils 4 Alfalfa 6 or more Grasses 3 to 4 Depth of rooting is impaired by hard soil layers and poor drainage. Irrigation This pasture is used in conjunction with dry-land pasture and range feed. The green feed pro- duced under irrigation extends the supply after range pasture dries up. [8] Hm Improper irrigation and lack of drainage facilities to handle excess surface water reduce pasture yields and provide breeding areas for mosquitoes — a public nuisance and health hazard. should begin before the available mois- ture within a major portion of the depth of rooting has been used. To determine when irrigation is needed, inspect the soil for moisture con- tent with a shovel, tube, or auger. Also watch for signs of wilting in sandy areas which may require more frequent irriga- tion. An inspection after each irrigation will show whether enough water has been applied to wet the soil throughout the rooting zone of the plants. Because irrigated pastures require more frequent irrigations than do most other irrigated crops, special care must be taken to prevent waterlogging the soil — a condition that will adversely affect the crop, and encourage undesir- able, water -loving weeds. Do not irri- gate while stock are on the pasture or until the surface of the soil has dried* Wet soils are compacted from trampling with the result that root growth is retarded, water fails to pene- trate the soil adequately, and growth is greatly reduced. Leaching Irrigated pastures are often used in the early stages of alkali reclamation. Be- cause pasture plants require frequent irrigation, excess salts are leached from the soil. In order to leach, adequate sub- surface drainage must be provided for removal of water containing the leached salts. In severe cases of alkali, highly salt-tolerant plants such as Bermuda- grass or Rhodesgrass are used. Mosquito control Mosquitoes become a public nuisance and a hazard to health and comfort under poor irrigation practice. Excess surface water may provide a breeding ground for large numbers of mosquitoes. The types that develop most rapidly need at least three and one-half to four days in water, to reach the adult stage, even under extremely warm interior valley temperatures. It has been found that the lower the field irrigation efficiency, the higher the mosquito population and the lower the yield on irrigated pastures. [9] Water should not be allowed to stand on an irrigated pasture longer than 24 hours following an irrigation. Re-use of water It is difficult to irrigate without losing some of the water through the drainage system at the ends of the checks. Return- flow systems conserve this water for re- use. In most cases water can be recircu- lated at a cost per acre-foot substantially lower than the original cost of pumping it from the ground. The lift is small com- pared with that from the average well. Currently operated installations indicate a cost ranging from $1 to $1.25 per acre- foot for the water recovered through return-flow systems. Recirculation systems can be installed to operate by : ( 1 ) pumping from a low- end collecting basin into a supply ditch; (2) pumping from a drainage canal into the main ditch; or (3) pumping from a low-end collecting basin into the main pipeline system. A common and efficient practice is that of using return-flow water to irrigate adjacent, lower lying fields. Return-flow systems do not eliminate the need for careful and efficient water management, but they do result in in- creased yields, better weed control, re- duced mosquito populations, and road protection. A farmer has the legal right to re-use waste water from his own land, provided he recovers the water before it leaves his property. Recirculated runoff water is usually of satisfactory quality for irriga- tion purposes except when it contains excessive amounts of salts. Discharging of drainage water on roads, railroad rights-of-way or neigh- boring properties is an act of negligence. Return-flow systems conserve water, and result in better weed control, reduced mosquito popula- tions, and increased pasture yields. They do not, however, eliminate the continued need for careful water management. Seedbed Preparation and Seeding A good seedbed is firm enough so that the soil particles are in close contact with the seed. Except where the seeds are to be germinated by irrigating, the seedbed must contain sufficient moisture to ger- minate the seed when sown and to sup- port growth until irrigation or rainfall begins. Several preliminary operations are in- volved in seedbed preparation, including disking, dragging, land planing, and harrowing. For fall seeding, the ground is worked when nearly dry or after weeds have germinated following irrigation or early rains. In spring, the ground nor- mally requires harrowing or disking. Often a preliminary stirring of the soil is made to encourage germination of spring weeds before planting. Time of sowing Sowing time varies in different" parts of the state, usually depending upon rain- fall and temperature conditions. South coastal counties experience little diffi- culty in establishing a stand at any sea- son of the year. In the interior valleys, sowing may be either in the fall or early spring. Spring sowings are best in the northern counties and in the mountains, where severe winters may kill fall-sown seedlings. Spring sowings should be made as soon as the temperature is warm enough to germinate the seed. Early sowing makes it easier to maintain favorable moisture conditions until the seedlings are well established. Weed control may be easier with spring plantings because they can be clipped at the proper time. Fall sowings must be early enough for seedlings to make good growth before cold weather sets in and before vigorous winter-growing weeds smother them. Well-established fall-sown pastures will achieve full production the first season. In the Sacramento Valley, fall sowings should be before October 15. In the southern San Joaquin Valley, sowings as late as November 15 have been success- ful. Seed Seed costs represent only a small part of the investment in a pasture. Only seed of high germination and purity should be used. Low-cost seed is not always the most economical. The use of certified seed is advisable to assure the grower that he is getting the desired varieties, high purity, and freedom from noxious weeds. Good pasture mixtures are offered by many seed firms. The individual species can also be purchased separately and mixed to provide the desired combina- tion of grasses and legumes. Seed inoculation For normal, vigorous growth, legumes must have root nodules, formed by rhi- zobia, the bacteria that fix nitrogen from the air for use by the plants. Legume seed may be inoculated with these bac- teria before planting, at a cost of only a few cents per acre. Commercial cultures of the bacteria, including directions for application, may be purchased from seed dealers. Differ- ent legumes or groups of legumes require different kinds of bacteria. Sowing Methods of sowing include drilling, broadcasting, or the use of a ringroller with a sowing attachment. Sowing is also done by airplane. Since the legume seeds tend to settle to the bottom of the mix- ture, the grasses and legumes are gen- erally sown separately. Any method that will give an even distribution of species sown no deeper than Yo inch is satisfac- tory. Ringrolling or cultipacking should follow the seeding operation. Nurse crops are not recommended except where un- [ii usual conditions prevail, such as severe winds that move light soils. Fertilizing at time of planting Applications of about 250 pounds of single superphosphate per acre may greatly stimulate seedling growth of legumes on soils which are known to be acutely deficient. Many phosphorus- deficient soils are also low in organic matter and nitrogen. At such locations the use of about 200 pounds of am- monium phosphate sulphate per acre is recommended on weed-free fields. On weedy fields, ammonium phosphate con- taining a low ratio of nitrogen to phos- phorus, such as 11-48-0, 13-39-0, 21-53- 0, should be used. These materials should be applied at rates sufficient to give about 50 pounds of phosphorus per acre ex- pressed as P 2 5 . The fertilizer materials may be broad- cast ahead of sowing or applied through a fertilizer spreader or a fertilizer attach- ment on a grain drill provided the seed and fertilizer are applied separately. Banding of fertilizer below the seed has proved very successful. On soils of moderate to high phos- phorus supply, the application of ferti- lizer materials at planting time may not be necessary or should be delayed until the need has been established. Pasture Plants Legumes Ladino clover, a perennial, is a large form of white clover introduced from Italy. It spreads by means of creeping stems (stolons) which root at the nodes. The plants are usually shallow rooted, with most of their roots in the surface 6 to 12 inches of soil, but they may ex- tend to a depth of 24 inches or more. Ladino is therefore ideally suited for use on shallow, hardpan soils. Its growing season is as long as that of other usable legumes. Ladino is winter-dormant in most parts of the state, and has a slight production sag during midsummer which can be partially overcome by phosphorus fertilization. The characteristics which make it the most valuable legume in irrigated pastures are high quality and rapid recovery after grazing. In many older pastures, Ladino shows a yellow streaking or discoloration in the leaves. This is caused by a virus disease that is transmitted by leafhoppers, and for which there is no known control. This virus is most apparent in late winter and early spring. A severe infection decreases production. Narrowleaf (prostrate) trefoil is a long-lived perennial with a relatively deep, but branching, taproot. The stems grow flat along the ground except in very thick stands or in mixtures where com- petition for sunlight causes them to grow more upright. Growth begins when aver- age daily temperatures range from 40° to 50° F, with temperatures around 80° believed to be most favorable. Trefoil withstands high summer temperatures up to 120° in the Imperial Valley. This type of trefoil is not suited to areas that have hard, killing freezes since it is subject to winter killing. Narrowleaf trefoil grows under a wider variety of soil conditions than does alfalfa or Ladino clover. It is one of the few legumes in common use that is capable of producing good pasture under conditions of high salt and poor drainage. Because trefoil does not cause bloat, it is widely used even where other legumes may be more productive. Broadleaf (erect) trefoil has a more upright growth than does narrow- leaf. The leaves are broader, with indi- vidual leaflets usually more than half as wide as long. There are many varieties of broadleaf trefoil, most of which have coarser stems than narrowleaf, but sim- ilar flowers and pods. Broadleaf trefoil is almost completely winter dormant, [12] and is more resistant to cold than is narrowleaf. It can therefore be used at higher elevations where winters are cold. Roots of broadleaf trefoil are deeper than those of narrowleaf, and the plants are more drought-resistant. Broadleaf trefoil is much less tolerant of poor drainage or overirrigation than is nar- rowleaf. Its production is excellent on irrigated pastures in the Sierra Nevada foothills, where water is limited and soils are coarse-textured. Broadleaf tre- foil does not present a bloat hazard. Both types of trefoil are poor competi- tors with either Ladino clover or grass. Where moisture and fertility conditions are favorable for the vigorous growth of clover and grass the trefoil may be crowded out of the mixture. Alfalfa, when grown on adapted soils, will yield more than any other pasture plant or mixture. Normally the same variety recommended for hay production should also be used for pasture. Alfalfa for pasture should be grown in pure stands. Its use could be greatly extended, especially for dairy pasture, by carefully controlled grazing practices in combina- tion with dry feeding of grain or Sudan hay to control bloat. Alsike clover is a perennial used chiefly in the northern counties at the higher elevations. It is able to withstand wet, cold, heavy soils better than do many other legumes. It is not suitable Narrowleaf trefoil (right, top) grows better under a wider variety of soil conditions than does alfalfa or Ladino clover. It is the only legume in common use capable of producing good pasture under conditions of high salt and poor drainage. Broadleaf trefoil (right, bottom) has a strong tendency toward winter dormancy, and can therefore be used at higher elevations where winters are cold. It is grown successfully in irrigated pastures in the Sierra Nevada foothills. Trefoils do not present a bloat problem. Characteristic leaf shapes of broadleaf trefoil (left) and narrowleaf trefoil (right). for areas in which high summer temper- atures prevail. Strawberry clover is a perennial, somewhat resembling Ladino clover in growth habits. It is more alkali- and drought-tolerant than Ladino clover, but is more susceptible to Sclerotinia, a fungus disease favored by cool, wet con- ditions. It is now being used to a limited extent only. A variety called Salina has given superior yield in comparison with common strawberry clover. It has re- mained productive over a nine-year period in sheep pastures at the Experi- ment Station at Davis. It is highly toler- ant of poorly-drained conditions, but produces most abundantly on fertile, well-drained soils. Red clover, usually a biennial, some- times acts as a short-lived perennial. It does best on well-drained soils. The large, leafy, fleshy stems grow upright from a central crown. It has a heavy, but rather short, semi-tap root. Although red clover is subject to mildew, this does not appear to discourage cattle from eating it. However, it is not extensively used, and has few advantages over other pas- ture legumes. Grasses Annual or domestic ryegrass is particularly valuable for its ability to produce an early, heavy spring growth. It is more stemmy and less leafy than is perennial ryegrass, but much more palat- able. It contains a mixture of many types of plants ranging from strictly annuals to short-lived perennials. Perennial (English) ryegrass is similar to annual ryegrass, but does not grow so rapidly. A finer-stemmed plant with many basal leaves, it grows late into the summer and resumes growth with the approach of cool fall temperatures. Rust is a problem at certain times. Orchardgrass is a perennial, bunch- type grass characterized by its blue- green color, flattened stems, and tufty manner of growth. It is very palatable in the early stages of growth, but be- comes coarse and tough as it matures. Occasional mowings and thicker seed- ings will discourage its tendency to form large clumps or bunches. It starts growth later in the spring and goes dormant earlier in the fall than does perennial ryegrass. Orchardgrass produces some- what better during the warm seasons than does ryegrass. Tall fescue is a deep-rooted, strongly tufted perennial with a long growing season and high forage yields. It pro- duces well in the winter on heavy, fertile soils, and its heavy sod makes it desir- able for winter grazing. Tall fescue has declined in popularity as an irrigated pasture grass because of its extreme aggressiveness and coarseness. Dallisgrass, a perennial, has a deep, strong root system, and grows in clumps which tend to die out in the center and enlarge around the edge as the plant ages. It starts growth rather late in the spring, and becomes dormant in the fall. It is strictly a warm-season grower, pro- ducing very heavily during the summer months. It will not survive the winter in the colder portions of the state. Some [14] irrigation districts oppose the use of this grass because its light, oily seeds float on water, and the plants become estab- lished along ditchbanks. Plants used occasionally Bur clover, a winter annual, is en- tirely dependent upon seed for repro- duction. It is used to a limited extent in the southern part of the state. Yellow sweet clover is a summer- growing biennial used in the early stages of reclamation on alkali soils. Rhodesgrass, a leafy, summer-grow- ing, fine-stemmed perennial, spreads by running branches which root and pro- duce a tuft at every joint. It is used in the southern San Joaquin Valley and the southern counties. It is more alkali- tolerant than are any of the other regu- larly used irrigated pasture grasses. Coastal Bermuda is a highly pro- ductive hybrid developed in Georgia. It has larger stolons and rhizomes, and longer leaves and internodes than com- mon Bermuda. Coastal Bermuda pro- duces very few seed heads, and those that are produced rarely contain viable seed. It is propagated by stolons. Irrigated Pasture Mixtures Grasses and legumes are usually grown in mixtures for irrigated pasture, except for alfalfa, which is normally grown in pure stands for grazing. Birds- foot trefoil also is frequently grown alone for pasture when used on salty or poorly drained soils. Grasses have certain advantages over legumes : 1. They give better bloat control. Among the legumes, only birdsfoot tre- foil effectively controls bloat. 2. They insure higher dry-matter in- take. (Legumes are normally higher in moisture than are grasses.) 3. Many of them provide earlier spring grazing and later fall grazing than do most legumes. 4. They develop a thick turf which discourages weeds and reduces damage from trampling. The legumes, likewise, have definite advantages over the grasses: 1. They are higher in protein and mineral content. 2. They maintain or improve nitrogen fertility by symbiotic nitrogen fixation. 3. They provide higher summer pro- duction than do most grasses. Legume and grass mixtures combine certain advantages of each group. How- ever, mixtures should be kept relatively simple, and in some cases, pure seedings may be better. Complex mixtures con- taining many species are seldom so pro- ductive or easily managed as are the better species in simple mixtures. Proponents of complex mixtures call attention to the fact that each species has a slightly different growth rate and pro- duction peak. It is assumed that, as each reaches its rapid growth period, it will join the other species in providing con- tinuous pasturage for the entire growing period. What actually happens is that competition among species nearly elimi- nates the less aggressive ones, and the more aggressive plants dominate the mixture. Thus, instead of continuous pasture, production is confined to the growth period of the dominant species. Simpler mixtures permit individual man- agement for each species. A series of several such mixtures, sown in separate fields, could provide a pasture program to fit the particular needs of the livestock operator. Field trials with various species and mixtures were conducted at the Experi- mental Farm at Davis. Table 1 shows the results. Alfalfa alone produced a greater yield of dry matter and protein than did any other species or mixture. There was no advantage to including a grass with alfalfa since none was able to compete in sufficient quantity to con- [15] Table 1 — Dry-matter and Protein Yields of Various Pasture Species and Mixtures (Second year after seeding) Factor Dry matter at 12% moisture Average protein Protein yield Species : Alfalfa tons per acre 8 8 5.7 5.6 1.2 1.2 7.2 6.6 6.5 6 5 6.5 6.4 per cent 25.0 23 24.2 13.3 11.4 22.6 22.5 20.0 22.6 20.9 22.2 lbs. per acre 4,402 Ladino clover 2,636 Narrowleaf trefoil 2,704 Orchardgrass Perennial ryegrass 322 262 Mixture : Alfalfa-orchardgrass Alfalfa-ryegrass Ladino-orchardgrass 3,246 2,976 2,610 Trefoil-orchard grass Ladino-ryegrass Trefoil-ryegrass 2,932 2,734 2,850 trol bloat. Grasses alone, without fertili- zation, were very unproductive and poor in quality. In another experiment, a mixture of orchardgrass, perennial ryegrass, and tall fescue, fertilized with 1,000 pounds of ammonium sulfate per acre, was less productive than were these same grasses growing with Ladino clover without fertilization. At the Imperial Valley Field Station, beef steers gained nearly twice as many pounds per acre on alfalfa as did a similar group of steers on tall fescue that received a total of 120 pounds of nitrogen per acre in three applica- tions. Certain rules should be followed in preparing a pasture mixture for a par- ticular area or purpose: 1. Select the legumes first, on the basis of adaptation to soil, climate, and type of livestock. The level of production is based largely upon the legume content. 2. Choose the grass or grasses that are compatible with the legumes selected. Avoid putting an aggressive legume with a slow-growing grass and vice versa. 3. Manage the pasture (irrigation, fer- tilization, and grazing) on the basis of the requirements of the legume in most cases. Exceptions to this rule may be advisable in areas where legumes nor- mally outgrow the grasses. Recommended mixtures The suggested mixtures, in pounds of seed per acre, are based in part upon experimental evidence and in part upon the authors' observations and judgment. The mixtures may be modified to fit spe- cial situations. Hardpan soils, shallow topsoil Dairy ancl beef cattle: Ladino clover 3 Orchardgrass 10 Total 13 Or Ladino clover 3 Common ryegrass 2 Perennial ryegrass 3 Orchardgrass 6 Total 14 [16] Sheep and hogs: Ladino clover 4 Heavy soils, poorly drained Dairy and beef cattle: Ladino clover 2 Narrowleaf trefoil 3 Orchardgrass 10 Total 15 Or Ladino clover 2 Narrowleaf trefoil 3 Common ryegrass 2 Perennial ryegrass 3 Orchardgrass 6 Total 16 Sheep and hogs: Ladino clover 2 Narrowleaf trefoil 4 Total 6 Deep soils, medium to light textured All classes of livestock: Alfalfa 20 Saline (salty) soils, poorly drained Narrowleaf trefoil 5 Alfalfa 2 Sweet clover 2 Tall fescue (Guars) 3 Common ryegrass 2 Perennial ryegrass 3 Total 17 Horses prefer rather coarse, stemmy grasses for most of their grazing ration. From 10 to 20 per cent legumes meets these requirements, although such a low percentage will hardly maintain maxi- mum forage yields unless heavy applica- tions of nitrogen fertilizers are made. Goats do best on the type of pasture recommended for cattle and sheep. Palatability Palatability of a forage plant is indi- cated by the readiness with which it is selected and eaten by livestock. Differ- ences in palatability can be a factor of considerable importance if the forage offered is not eaten in sufficient amounts for satisfactory animal gains. Small dif- ferences in palatability may not directly affect animal gains, but may have im- portant effects upon the botanical com- position of the pastures. The more palat- able species are grazed more closely so that the plants are weakened, while the less palatable ones thrive and thicken in the absence of grazing. Various factors affect palatability: 1) Food preferences tend to be similar among animals of the same class and breed, but there is also good evidence to indicate that particular animals have individual tastes. Age and degree of appetite influence preference. Animals that are hungry when turned in to graze become more selective in their choice of forage as their hunger is satis- fied. Young animals are usually more selective than are older ones; fat ani- mals, more selective than thin ones. Sheep are more selective than cattle. 2) Stage of growth influences palatability. Young plants are generally succulent. As plants (especially grasses) mature, palatability decreases. 3) Weather often determines choice of forage. For example, in spring, when the weather is cool and rains are frequent, sheep have been observed seeking coarser and dryer grasses rather than succulent legumes. As the season becomes warmer and dryer, the animals shift to the legumes and leave the grasses. Sunlight is also a factor. Grasses growing in the shade of trees or of taller plants are less readily eaten than are those in full sunlight. 4) Soil conditions, such as drainage, degree of alkalinity or acidity (pH value), and available min- erals, have an indirect effect on palat- ability. A relationship has been suggested between these conditions and the sugar content of grasses. Soils fertilized with phosphorus may be preferable to non- fertilized ones because this element is [17] involved in sugar formation in plants. Exceptionally high nitrogen content in soil may result in less palatable plants (such as may occur around urine spots in pastures) as a result of a nitrogen/ phosphorus imbalance which reduces the sugar content. Poor drainage and low pH may also decrease palatability. Under systems of controlled grazing, in which each part of the pasture is grazed down quickly and uniformly, small differences in palatability may be unimportant. With less intensive control of grazing, however, even small differ- ences in palatability could convert a good pasture into one largely dominated by the less palatable species. Further- more, if the more palatable species is the legume in the mixture, pasture yields may be drastically decreased because of nitrogen starvation. Pasture Management The most important steps in pasture management are: irrigation, fertiliza- tion, regulated grazing, and weed con- trol. All of these factors are essential to the maximum production of the pasture, and any one of them can limit produc- tion if not done correctly and in the right relation to the other practices. Irrigation The only aim of irrigation is to main- tain a continuous supply of readily avail- able soil moisture for the plants in the pasture mixture. Since most pasture mix- tures contain several plant species which root to different depths, adequate soil moisture must be maintained throughout the entire root zone. If infrequent, heavy irrigations are used, the deeper-rooted plants, such as alfalfa and trefoil, will become dominant at the expense of the shallower-rooted Ladino clover. Since Ladino clover is usually the most impor- tant plant in the pasture mixture, the irrigation practice should be designed to maintain adequate clover growth. Ladino clover produces a large number of shallow roots from the joints of the main stems, and the irrigation practice should provide for water application im- mediately following grazing or clipping and at frequent enough intervals to keep the top 6 inches of soil from becoming completely dry. This will require close coordination between the grazing and irrigation cycles. One of the most common faults in pasture management is failure to irrigate early enough in the spring. During this period, when rainfall ceases abruptly and temperatures warm rapidly, soil mois- ture is quickly depleted in the critical area of the root zone. Irrigated pastures that are allowed to suffer for lack of water at this period are extremely diffi- cult to bring back to maximum produc- tion. (For a discussion of irrigation methods, see pages 5-10.) Fertilization Irrigated pastures, like any crop, re- quire a high level of soil fertility for maximum yields. Although animal ma- nure is a valuable soil nutrient, manures return only about one-third of the total nutrient supply in the forage eaten by the animals. Addition of commercial fertilizers is recommended for establish- ment and continued high production over a period of years. Elements most commonly deficient are phosphorus and nitrogen, with sulfur and potassium oc- casionally deficient in limited areas. Phosphorus deficiency is widespread on calcareous soils and on acid soils with a hardpan or claypan substratum — soils on which much irrigated pasture is grown. Phosphorus deficiencies are less common on deep, neutral, alluvial soils. Nitrogen is seldom present in suf- ficient amounts to provide for the needs of grasses. Although legumes in a pas- ture mixture fix substantial amounts of nitrogen, much of this nitrogen is util- ized by the legume itself. When luxuriant legume growth has occurred, the decay- [18] ing roots plus the manures of animals eating the forage provide organic nitro- gen for use by grasses. If a good stand of legumes cannot be maintained either by fertilization or by irrigation manage- ment, it will be necessary to apply sup- plemental nitrogen to obtain a satisfac- tory growth of grass. Either manure or commercial nitrogen fertilizer may be applied. Manures or other organic nitro- gen must be mineralized to ammonium or nitrate before the nitrogen can be used by grasses. After nitrogen is converted to the nitrate form, it leaches quickly in sandy soils or may be lost if soils remain saturated or waterlogged for extended periods. Since irrigated pastures require large amounts of water, it is doubtful that a commercial nitrogen application would be effective for more than 30 to 40 days. The nitrogen from organic sources such as manure top dressing does not leach so readily as does that from min- eral sources. Nitrogen does not give maximum stimulus to grasses on a phos- phorus-deficient soil unless phosphorus is also added. Similarly, on a sulfur- deficient soil, nitrogen is not effective unless adequate amounts of sulfur are present. Sulfur deficiencies are not so wide- spread as phosphorus deficiencies. They are most likely to occur in northern and central California where water of low sulfur content is used on light soils. They rarely occur in southern California or where pumped underground water con- taining adequate sulphate is applied. Potassium deficiencies on irrigated pastures are at present of limited extent in California. Fertilizing the established pas- ture. Commercial fertilizers may be used to influence both the volume of feed produced and the proportion of grass to legume in the mixture. Many irrigated pastures require ap- plications of phosphorus to maintain or improve the growth of legumes. On acutely deficient soils, 80 to 120 pounds of P 2 O r , may be required to provide satisfactory growth of legumes. On mod- erately deficient soils, 40 to 80 pounds of P 2 5 annually may be sufficient to maintain adequate growth. Where phos- phorus is in short supply, the application of this nutrient increases both the amount and proportion of legume in the mixture. Phosphorus may be supplied by either single or treble superphosphate broad- cast preferably during the dormant sea- son before growth starts in the spring. In areas where sulfur deficiencies are also suspected or known to occur, single superphosphate, which contains about 9 per cent sulfur, should be used. Where adequate phosphorus is pres- ent, the application of additional phos- phorus will not increase the growth of the legumes nor change the proportion of legumes to grass. There are several conditions under which the use of nitrogen may be neces- sary and desirable. Nitrogen applications may often be used to increase the growth of grass in the forage mixture. Where early spring feed is needed, a late winter application of nitrogen will usually pro- vide earlier grass growth and frequently more total feed. If the soil is deficient in phosphorus, it also must be applied in order to make the nitrogen effective. From 40 to 60 pounds of actual nitrogen per acre should be applied. Under aver- age irrigation intervals, this will be effec- tive for no longer than 30 to 40 days. Where legumes predominate and a threat of bloat exists, application of nitrogen may greatly increase the growth of grass present. Continued application of heavy amounts of nitrogen may stimulate so much grass growth that the legume may be crowded out of the pasture mixture. In the hot interior valleys where some legumes do not thrive in the summer heat, vigorous growing grasses, such as Dallisgrass, may be greatly stimulated by the application of the nitrogen alone or with phosphorus if needed. Under [19] such conditions, forage production may be about doubled by application of from 180 to 200 pounds of nitrogen broadcast at rates of 30 to 40 pounds every 30 days. Equally effective results may be obtained at lower application costs by the con- tinuous use of low concentrations of nitrogen solutions in the irrigation water throughout the summer months. Liquid-manure pits conserve plant food and offer a convenient way to re- turn corral and barn manures to pas- tures. The material may be pumped into tank wagons and distributed daily or it may be returned to pastures through irrigation systems. Liquid manures con- tain more nitrogen than phosphorus, and may be expected to stimulate grass to a greater degree than the legumes. Controlled grazing Under ordinary farm conditions, the management of grazing can have a greater influence on the condition of the pasture than any other factor under con- trol of the operator. Methods of grazing have a pronounced influence upon botan- ical composition of a pasture, its leafi- ness, yield, and chemical composition (including such important constituents as protein and minerals). The impor- tance of grazing management has not been clearly understood nor fully appre- ciated. The objectives of good grazing man- agement are to: (1) produce feed of good quality; (2) maintain high pro- duction; (3) obtain efficient utilization; (4) avoid soil compaction. Controlled grazing can help accomplish these ob- jectives. Grazing methods. These may be classified as: (1) extensive or continu- ous grazing; (2) rotation grazing; and (3) daily ration or strip grazing. With continuous grazing, there is little or no subdividing of pastures. Animals are permitted to graze freely over the entire area, selecting first those species and portions of plants which are most palat- able. Selectivity in grazing results in a decrease of the most palatable species and an increase in the unpalatable plants. The rotation grazing system requires intensive grazing on an intermittent basis throughout the growing season, using heavy concentrations of animals at each grazing period. Under this sys- tem, the pasture is subdivided into small units, and the animals are rotated from pasture to pasture as each is grazed down in turn. Systems differ greatly in number of subdivisions, frequency with which animals are moved, and length of Intensive grazing on irrigated pastures. Cattle have just been turned in. Note abundance of luxuriant foliage. Rotation grazing encourages maximum production of high quality forage. »fess* "V' : ' growing intervals between each grazing. Research and farm experience have shown that, for most conditions, the rota- tion system should contain six pastures, each grazed five days before the stock is moved on to the next pasture. With this system, a regrowth period of 25 days is possible between grazings. Irrigations should immediately follow grazing. If repeated every 10 days, three irrigations will be possible between each grazing cycle. Selectivity still occurs with rota- tion grazing, but its importance is deter- mined almost directly by the time re- quired to graze the pasture completely. The longer this takes, the more important selectivity becomes. With daily ration or strip grazing, the area grazed is restricted to the amount which can be grazed down in one day or in one feeding (see diagram, p. 22). Portable electric fence is used, and the area upon which grazing is permitted is judged by how full the animals are or by the amount which may be left ungrazed. Adjustments in the size of the area to be grazed are made according to the rate of pasture growth or the amount of green feed required in the ration if sup- plemental feeding is practiced. The prob- lem of selectivity is least serious with this method of management. Waste of feed from trampling and from fouling with droppings is kept at a minimum. The cover photo shows a heavy con- centration of dairy cattle on a rotation system. The area in the foreground was grazed the previous day. Production of good quality feed can be controlled in part by grazing manage- ment. However, many other factors in- fluence quality, such as soil conditions, plant species, climatic conditions, ferti- lizer practices, and plant maturity. Stage of growth. This is probably the most important factor influencing chemical composition and feeding value. Early spring grasses and legumes are succulent, high in moisture and protein, but low in fiber. As the season progresses, days become longer, the temperature rises, and the plants approach the repro- ductive stage. Stems which produce the flowering parts appear and elongate rapidly. These stems have a higher dry- matter, carbohydrate, and crude fiber content than the leaves, and a lower pro- tein percentage. If the plants are per- mitted to reach an advanced stage of maturity, the high percentage of crude fiber results in a decrease of both pala- tability and digestibility. From a strictly chemical point of view, it might appear that the younger On suitable land, alfalfa will produce the highest forage yield per acre of all pasture species. Daily rationed grazing has permitted greater use of alfalfa pasture, especially for dairy cattle. 5th Day 4th Day 3rd Day 2nd Day 1st Day X /- / Lane f / / Permanent Fence Electric Fence Diagram of a rotation grazing daily rationed grazing layout. . « The chart opposite shows a 30-day grazing-irrigation The same basic plan can be used for regrowth cycle. * the grass, the greater its feeding value. This is not necessarily true. Animals may actually lose weight from severe scouring during the first few weeks on spring grass, as a result of its laxative nature and low dry-matter content. Care- ful rationing of young grass and use of good roughage will overcome this prob- lem. It seems reasonable to assume that the most satisfactory stage so far as the animal is concerned is somewhere be- tween the extremes of succulent early growth and the very fibrous, mature growth. Actively growing forages under favor- able growth conditions may contain 80 to 85 per cent water. In general, legumes are higher in moisture than are grasses although it must be recognized that both groups may show wide variability in moisture percentage. In studies con- ducted at Davis, it was found that all pasture mixtures increased in dry matter as the forage became older. One mixture of legumes and grasses averaged 16.5 per cent dry matter when cut at two-week intervals, and 21.4 per cent when cut at five-week intervals. Assuming equal in- take of fresh pasture at the two-week and five-week periods, the animals consuming the more mature forage would be ingest- ing nearly 30 per cent more dry matter. It is not known to what extent animals may compensate for degree of succu- lence when grazing pasture in which moisture contents differ. However, it is generally believed that animals on very succulent pasture will gain more rapidly if the dry-matter intake is increased by feeding of straw or dry hay on the pasture. In good irrigated pasture, the quan- tity of protein is adequate for most pur- poses. Unfertilized grass pastures seldom contain less than 10 per cent protein, on a dry-weight basis, while grass-legume pastures usually average 20 per cent or more. Rapidly growing pastures with a high percentage of legumes may contain nearly 30 per cent crude protein. The digestibility of crude protein usually amounts to about 60 per cent of the total, but may range from 50 to 85 per cent. [22] Grazing, Irrigation, and Regrowth Periods for a 30-Day Cycle Field number Days 1 2 3 4 5 6 1 Graze Graze Irrigate Irrigate Irrigate 2 Regrowth 3 Graze 4 Graze Graze Irrigate Regrowth Graze Graze Graze Irrigate Irrigate 5 6 7 8 9 Graze 10 Graze Irrigate Regrowth Graze Graze Graze Graze Irrigate 11 Irrigate 12 13 14 15 Irrigate Graze Irrigate Regrowth Graze Graze Graze Irrigate 16 17 18 19 Graze 20 Graze 21 22 23 Irrigate Irrigate Regrowth Graze Graze Graze Graze Irrigate 24 25 Graze 26 27 28 Irrigate Irrigate Irrigate Regrowth Graze Graze Graze 29 Graze 30 Graze Plant-animal relationships. In the foregoing discussion, particular stress has been given to the nutritional value of the forage produced in pastures. How- ever, the needs of the plant as well as the animal must be considered in the development of any sound program of pasture management. There are few fields of research in which such careful con- sideration must be given plant-animal re- lationships as in that of grazing manage- ment. In devising any system of controlled grazing, whether rotation or ration, it is important to know the plant responses when the pasture is grazed at varying in- tervals. Little advantage is gained by grazing at a very early stage if this re- sults in decreased yield, weed infestation, and a ruined pasture. Neither is it wise to favor the plant entirely at the expense of the animal. The plant responses to various systems of harvesting, grazing, or clipping are [23] determined by the physiology of plant growth. Materials that enter the plant through the roots and leaves are rela- tively simple, and are inorganic. Water entering the plant through the roots com- bines with carbon dioxide, which enters the leaves from the air, to form simple carbohydrates — a process requiring light, and known as photosynthesis. Other, more complex substances formed in the plant from these organic and in- organic compounds make up the various structures of the growing plant. All new plant tissue, therefore, is a result of photosynthesis. The rate at which this process is car- ried on in the plant is conditioned by many factors, one of which is leaf area. It is known, for example, that an alfalfa plant which has been recently defoliated will grow faster than new photosynthetic materials can be manufactured in the plant. This early growth must, therefore, take place partially at the expense of carbohydrate materials stored in the root. As the leaf area expands, the rate of photosynthesis catches up with, and eventually surpasses, the rate at which carbohydrates are being used for growth alone. Surplus material is again stored in the roots, and the entire process is repeated. It is evident that a frequently defoliated plant would eventually be starved or at least much reduced in growth rate, and that if a large leaf area is allowed to develop before defoliation, growth rate will be increased. A three-year study conducted at Davis shows the extent to which yields are im- proved by permitting additional leaf growth to accumulate. The data in table 2 show an average of two different mix- tures used in the study. It is evident that protein percentage decreases as yields increase. Obviously, there is a point be- yond which increased yields may be more than offset by decreased quality, and the objectives of the livestock enterprise will determine which is to be emphasized. The data above, together with the practical experience of farmers, show that a growth interval of 25 to 30 days between grazings is very satisfactory. Even shorter intervals should be used if high quality is of primary importance. Intervals longer than 30 days frequently result in much waste from trampling unless strip grazing is being practiced. The diagram on page 22 shows a very successful system of rotation grazing which can be used where the intervals between irrigations average 10 days. The grazing, irrigation, and regrowth periods for one complete cycle of 30 days are shown in the chart on page 23. It appears to be quite important that irrigation immediately follow grazing to prevent heat damage to exposed Ladino stolons. Subsequent irrigations during the regrowth periods can be adjusted a Table 2 — Effect of Cutting Frequency Upon Yields and Protein Percentage of Two Irrigated Pasture Mixtures (Yields and protein figured at 12 per cent moisture) Harvest Ladino-grass mixture Trefoil-grass mixture frequency Yield Protein Yield Protein Two weeks tons per acre 5 59 6.65 7 33 8 00 per cent 23.8 20.5 19.1 17.2 tons per acre 3.64 4.57 5 23 6 92 per cent 21 6 Three weeks 18.8 Four weeks 16 5 Five weeks 16 4 [24] Effect of frequency of clipping or grazing. Left: three months' growth without clipping; center: clipped to 3 inches every three months; right: clipped to 1 inch every week for three months (note greatly retarded growth). Good pasture management permits normal and necessary root development. day or two either way to accommodate labor and water supply. However, it is very important to allow four or five days for the field to dry before grazing since trampling of moist land damages the roots, compacts the soil, and reduces the rate of water infiltration. Thousands of acres of irrigated pasture in California are not producing to full capacity, and require more frequent irrigation than originally needed, simply because of compaction. To obtain adequate water penetration, some operators are forced to hold the water on the land for extended periods of time. This in turn causes the drowning or scalding of some pasture species. Aside from weeds, soil compac- tion is perhaps the next most serious problem facing the pasture operator. Once the soil has become compacted, cor- rective treatments cannot be effectively applied without plowing the stand. Land needing irrigation at more or less than 10-day intervals will require a [25] different number of pastures or different number of days on each. For example, on land where irrigation is at 8-day inter- vals, 24 or 32 days may be required to complete the entire grazing cycle. In every case, the need for timely irrigation is of greater importance than the re- growth period, and should be the domi- nant factor in planning the grazing pro- gram. During early spring and late fall when less water is used, the grazing cycle as well as the irrigation cycle must be lengthened. Supplemental feeding must compensate for lower production during these periods. The carrying capacity of pastures grazed in rotation will have to be worked out on the basis of experience. Under average conditions and with little sup- plementation, an acre should supply ade- quate forage for 50 to 60 mature cattle for a day. Therefore, a field to be grazed for five days should carry 10 to 12 cattle per acre. Not all of the feed produced in a pas- ture is actually consumed by the grazing animal. Much of it is wasted as a result of trampling, manure droppings, or leaf fall. Recent studies at the University of California showed that 70 per cent of the forage above a 2-inch height was utilized by dairy cattle strip grazing a Ladino clover-orchardgrass mixture. Utilization was 74.3 per cent by rotation grazing. A similar comparison with beef cattle graz- ing alfalfa pasture showed utilization of 71 and 76.2 per cent for rotation and strip grazing, respectively. In both of the above-mentioned stud- ies, the rotation system called for ani- mals on each pasture for five days before being rotated to another field. It is be- lieved that the amount of waste would be larger if the grazing period were longer than five days. Animals can be forced to utilize a larger percentage of the forage but in doing so, daily gains or milk pro- duction may be reduced. Some of the loss may be recovered by cleaning up the fields with dry cows or other stock in which maintenance rather than gains or milk production is desired. Overgrazing, lack of drainage facilities, and low fertility contribute to excessive weediness. Turning livestock on to pastures that are too wet results in poor water penetration because of compaction. [26] Weed control Land grading. Proper and careful land grading is the first step for control of weeds in an irrigated pasture. Water standing in low spots will drown out the pasture plants and provide ideal condi- tions for many of the water-loving weedy species, such as curly dock, buckhorn and sedge. High spots which receive in- sufficient irrigation likewise tend to en- courage other types of weeds, such as yellow star thistle, which do well under dry conditions. Mowing. Mowing annual weeds be- fore they mature is one of the cheapest and best methods of preventing their in- crease and spread. However, mowing will not kill perennial weed types, such as dock and sedge. Even in mature fields that are being pastured, occasional mow- ing is beneficial in reducing weeds and promoting even cropping and full utili- zation of forage. Chemical control. This is most effec- tive when used to supplement good man- agement and cultural methods. 2,4-D can be used on established Ladino and/or trefoil-grass pasture. It is effective in the control of dock, buckhorn, plantain, chicory, sedges, star thistle, wild lettuce, and other broad-leaved weeds. Weeds on supply ditches can also be controlled by chemicals. In using 2,4-D, local regulations must always be followed. These points are also important when spraying Ladino or tre- foil pastures with 2,4-D: 1. The best time to spray is in April after the legumes have started growing well. Do not spray dormant legumes (November to January) . 2. The amine form of 2,4-D appears to be safer to use than does the ester form. 3. Use from y 2 to % pound of actual 2,4-D acid equivalent per acre. If buck- horn is the principal weed to be con- trolled, use % pound of actual 2,4-D per acre. For best control of buckhorn, the field should be grazed or mowed back before spraying to expose the low grow- ing plants, but this may increase the damage to the legumes. Dock and chic- ory appear to be readily killed by 2,4-D in normal, unmowed or ungrazed stands. The sedges and dock are difficult to kill and may require treatment for several years before they are checked. 4. Ground-spray equipment gives very good results, provided 20 to 50 gallons of water are used per acre. Less water can be used with airplane application. 5. All 2,4-D-sprayed fields should be kept well irrigated following spraying. 6. Do not graze 2,4-D-sprayed stands during the recovery period — about 30 days for Ladino clover and longer for the trefoils. Chemical weed control is effective only where land is properly graded, drainage is adequate, and good irrigation and gen- eral management practices are followed. The greatest source of failure with any weed control practice either cultural or chemical is improper timing of the ap- plication. Once a pasture is infested with weeds, periodic spraying and mowing may be required throughout the life of the pasture. The weed population of a pasture is also affected by grazing practices, soil fertility, and crop rotation. Pasture plants that are grazed too frequently or too closely will not compete with aggressive weedy species. Adequate soil fertility permits the desired species to grow better and thus compete favorably with weeds. Poisonous weeds occasionally cause stock losses, but are rarely a problem where pastures are managed to permit good growth and adequate production of feed. Crop rotation A well-balanced program of crop ro- tation can include land devoted to pas- ture. Irrigated pastures do not remain [27] Pasture land should be included in the farm crop-rotation program since irrigated pastures do not remain at maximum production indefinitely. Rotation with other crops permits regrading of land, aids weed control, and provides for a more balanced farm feed production. at maximum production indefinitely. Or- dinarily, a pasture remains profitable not longer than five to eight years, and then begins to become weedy and difficult to irrigate. Satisfactory pasture renovation can best be accomplished through rotation with other crops. Forage production can be continued by using such crops as oats and vetch for winter feed and Sudangrass for summer pasture or for hay. Culti- vated annual crops, such as corn, milo, and small grains, help the reduction and control of weeds. (The ease with which corn fits into a rotation system that aids weed control is an important point in its favor.) Rotation permits regrading and deep tillage, such as chiseling or subsoiling, to help open up the soil for more efficient use of irrigation water and better control of weeds. A change of planting also per- mits use of newly developed improved varieties or strains, and provides an op- portunity to take advantage of the im- proved soil fertility. [28 Miscellaneous management practices Mowing, If the livestock numbers on any given farm are properly balanced with year-round feed supplies, there will probably be an excess of pasture during the spring months of flushest growth. By adjusting the rotation so that each pad- dock may be mowed at least once, this surplus may be used for hay. It also makes good silage when molasses or other additives are used. As the grazing season progresses, clipping after each rotation grazing will further reduce weeds, result in a uniform pasture growth for the next grazing period, and promote more nearly equal utilization of all pasture plants. Harrowing. Pasture should be har- rowed regularly to spread the droppings of cattle and prevent bunchy growth around manure clumps. Harrowing for this purpose is especially effective after an irrigation. A flexible type harrow does a better job of breaking up and spreading than does the rigid type. ] L/vesfock Management Supplemental feeding Irrigated pasture feed attains its max- imum efficiency when combined with supplemental feeding planned for a spe- cific type of livestock. Experience indi- cates that daily gains of good quality cattle are increased by supplemental feeding. The supplement ordinarily con- sists of a combination of hay and grain. Beef cattle are not normally finished on irrigated pasture. A period of from 30 to 60 days in the feedlot is generally re- quired to finish cattle to top market grade. Young cattle and calves particu- larly require supplemental feeding in order to make satisfactory gains on irri- gated pasture. On the other hand, cattle of lower quality, as well as older animals, may be advantageously marketed directly from irrigated pasture without the bene- fit of supplemental feeding. Producing dairy cattle are normally fed dry hay and a grain concentrate in addition to the irrigated pasture green feed. This prac- tice does not seem to be justified for low- producing herds. Lambs appear to make satisfactory gains on good irrigated pasture with no other supplement than dry roughage. Hogs make the most economical gains when self-fed grain while in pasture. Bloat Bloat is a hazard when cattle and sheep are grazed on pastures containing a high percentage of clovers and immature al- falfa. Several precautionary measures may be taken to minimize the problem: l.Mow strips in the pasture the day before cattle are turned in to feed. The dry feed in the strips will reduce the incidence of bloat. 2. Do not turn hungry cattle in on new, luxuriant, or immature growth, espe- cially in spring, without first giving them a fill of dry cereal hay or Sudangrass hay. Feeding straw may be of value under some^ circumstances. Alfalfa hay is less effective than straw in prevention of bloat. Green Sudangrass pasture and Sudangrass hay are the most effective Fattening animals will gain from Va to V2 pound more per day when given supplemental feed. All other livestock and pasture management practices must also be properly integrated. m mm feeds known at present for preventing bloat. 3. Rotation grazing has resulted in a noticeable lessening of the bloat prob- lem. With proper control of grazing, many dairymen and stockmen success- fully pasture alfalfa throughout the en- tire growing season. However, rotation grazing is not a reliable method for elim- inating the bloat hazard. 4. An adequate supply of nitrogen will produce maximum grass growth and aid in maintaining the desired grass-legume balance. Molybdenum toxicity Soils in certain areas of the state con- tain an excess of molybdenum. Plants growing in these soils, particularly leg- umes and some grasses, contain an amount that is toxic to cattle. Areas affected. The areas known to be affected at present include the west side of the San Joaquin Valley and, to a limited extent, eastward along the Kings River. The problem exists also in the Sacramento-San Joaquin Delta and in many of the south coastal counties. Molybdenum content of plants. The exact amount of molybdenum in plants that is sufficient to be toxic to cattle is not known, but is believed to be somewhere between 10 and 20 parts per million. The range of molybdenum in plants varies widely, depending upon its content in the soil. The following is an analysis of some plants from affected areas: PLANT MOLYBDENUM RANGE Legumes : parts per million Alfalfa 10 to 30 Birdsfoot trefoil 21 to 116 Ladino clover 7 to 103 Sweet clover 14 to 122 Grasses: Ryegrass 2 to 20 Orchardgrass 5 to 9 Sudangrass 2 to 8 Rhodesgrass 12 to 26 Burmudagrass 3 to 11 [30 The molybdenum content of pasture plants appears to decline with the age of the pasture stand. It is important that the pastures be kept in an active growing condition. Good cultural practices, such as adequate nitrogen fertilization, will permit maxi- mum growth of grass in the pasture. Animals affected. Young cattle and calves show the effects of molybdenum most noticeably. Some evidence also in- dicates difficulty with sheep pastured in areas known to be high in molybdenum. Symptoms. Molybdenum poisoning results in severe scouring and loss in weight to the point of emaciation. The hair coat becomes rough and dry, and changes color. Red Hereford cattle be- come a dirty yellow, and black animals turn mouse-gray. There is some evidence that cattle on affected pastures develop breeding difficulties. Symptoms alone are not sufficient for positive diagnosis. Since cattle scour from other causes, a chemical analysis of the forage should be made to determine the molybdenum content. Molybdenum apparently does not cause death, except of those cattle that have had prolonged access to affected forage. Prevention. Copper sulfate fed to cattle at the rate of 1 gram per head per day has proved effective in preventing most cases of molybdenum poisoning. In a few instances, when it has been neces- sary to go to 2 grams per day, there has been no ill effect on the cattle. The cop- per sulfate may be added to the drinking water, or it may be added to the grain mix. For details, see your local Farm Advisor. Pasture mixtures for affected areas. Since legumes generally contain a higher amount of molybdenum than do most of the grasses, it is recommended that pastures in affected areas be seeded largely to grasses. Feeding dry roughage on pas- ture. Providing cattle on irrigated pas- tures with free access to dry roughage ] has been helpful in reducing the symp- toms of molybdenum poisoning. Such feeding may eliminate all evidence of trouble where pasture plants contain only slight amounts of molybdenum. Ergot poisoning Ergot poisoning, although fairly rare in California, can result in severe dam- age and even stock loss when it does occur. It is a fungus disease which at- tacks grasses — mainly perennial ryegrass and Dallisgrass — when they are flower- ing and making seed. Ergot can be recognized first by the appearance of a sticky exudate or honey- dew on the seed heads, followed, in most grasses, by dark-violet to black "spurs" in place of, and noticeably longer than, the normal grass grain. Dallisgrass ergot does not form these dark, spur-like en- largements, but develops light, pinkish bodies which do not differ greatly in ap- pearance from the seeds. The presence of the honeydew should be regarded as a warning. Stock pasturing on ergotized fields are usually covered about their heads and bodies with the sticky, black exudate. When driven or forced to move, cattle that have consumed toxic amounts of ergot exhibit a staggering gait, trembling of the muscles, and nervous outbursts during which the animals fall. These symptoms may or may not be followed by paralysis. Cattle lost because of ergot poisoning have, in the majority of cases, either fallen down out of reach of food or have drowned in shallow water. Rotation grazing and mowing to keep grasses from developing seed heads will practically eliminate the ergot problem. Co-operative Extension work in Agriculture and Home tconomics. College of Agriculture, University of California, and United States Deportment of Agriculture co-operating. Distributed in furtherance of the Acts of Conoress of May 8, and June 30, 1914. George B. Alcorn, Director, California Agricultural Extension Service. 25iw-6,'59(C7762)L.L [31] : l^|i^- * 4#8P^p| THE COVER PHOTO shows how rota- tion grazing with dairy cattle may be accomplished on irrigated pas- ture. The area in the immediate foreground was grazed the previ- ous day. Note the heavy concentra- tion of cattle.