m CONTOUR PUNTiNG OF UNIRRIGATED PERENNIALS LLOYD N. BROWN CALIFORNIA AGRICULTURAL EXTENSION SERVICE • THE COLLEGE OF AGRICULTURE • UNIVERSITY OF CALIFORNIA • BERKELEY Plant on the Contour ORCHARDS/ VINEYARDS, BERRIES, AND OTHER PERENNIAL CROPS ^ ON ALL LAND STEEP ENOUGH TO ERODE DURING THE RAINY SEASON ^ TO HELP PREVENT SOIL MOVEMENT BY EROSION ^ BY PLANTING IN ROWS THAT CURVE AROUND OR FIT THE HILLSIDE— CONTOUR PLANTING ^ THE AUTHOR: Lloyd N. Brown is Specialist in Soil Conservation in the Agricultural Extension Service. [2] wtlSave$0it Contour planting of perennial crops on steep slopes is practiced under both irrigated and unirrigated conditions. Considerable difference exists between the methods used under the two conditions. THIS PUBLICATION DEALS ONLY WITH CONTOUR PLANTING OF PERENNIAL UNIRRIGATED CROPS. California has a considerable area planted to unirrigated perennial crops. A large part of this acreage is on soils so steep that they may erode during winter rains. Occasionally in these areas one finds an orchard planted on the contour, but the majority are square planted. The story is always the same: contour-planted areas are little if any damaged by soil erosion; square-planted areas show loss of top soil, gullying, and decline of trees and vines. Steep soils are usually relatively shallow and consequently are limited in the amount of rainfall they will hold. If rainfall occurs when steep soils already are saturated, or at rates which will not sink into the soil, runoff is bound to take place. Such runoff may cause loss of top soil and gullying. CONTOUR PLANTING, as discussed in this circular, means planting in rows curving around the hillside on a grade or fall of about 1 V2 feet in 100 feet of row. It is practical to contour plant soil which has a slope of 2 to 4 feet per hundred feet up to 15 or 20 feet per hundred feet. To be successful, contour planting must be supported by good management practices, such as raising of a good winter cover crop and, if necessary, the installation of annual drainage ditches. CAUTION: Three questions, important in all farming, are even more important in contour farming: Is the rainfall adequate? Is the soil suitable? Can the crop be raised at a profit? [3] SOIL PROFILES A soil profile is a vertical section of the soil from the surface through the underlying subsoil to a depth of about five feet, or to bedrock. This diagram illustrates, to a depth of five feet, three types of soil commonly found v/here contour planting may be considered. Slightly dense subsoil s Bedrock Dense clay subsoil p 1 \ ) I UPLAND SOILS TERRACE SOILS TERRACE SOILS ON WITH WITH BEDROCK SLIGHTLY DENSE DENSE CLAY SUBSOIL SUBSOIL [4 Suitable locution for contour planting Erosion hazard is the thing to consider. It must be considered with respect to Soil Type . . Soil Texture • . Steepness of Slope Soil Type On the opposite page are sketches showing three soil profiles to a depth of five feet. Soils of these general types fre- quently occur where contour planting is considered. The only way to find out which type of soil is present is to examine the profile. This can be done by digging holes with a shovel or auger, or perhaps by examining nearby roadcuts. Upland Soils on Bedrock. These soils have been formed in place by the de- composition of the underlying bedrock. If they are three feet deep, they are con- sidered good agricultural soils for most crops. Due to their limited depth, it is important to control erosion. If the sur- face six inches of a soil three feet deep is lost, one-sixth of the soil is gone— a very serious loss. Terrace Soils with Slightly Dense Subsoil. Generally speaking, these soils have been formed in two ways, as old alluvial deposits or valley fill and as old elevated coastal plains. On the margins of valleys, old valley fills which have been mostly washed away remain as terraces. The valley has then been partly refilled with the present soil which is usually of better quality than the higher and much older terrace soil. Along the coast, ter- races have been formed by the geologic uplifting of old shore lines. By which- ever method these terrace soils have formed, the subsoil is slightly heavier than the surface soil. However, the sub- soil is usually not dense enough to re- strict seriously the penetration of rainfall. Consequently, the erosion hazard may not be serious but should be carefully considered. Terrace Soils with Dense Clay Sub- soil. These soils have been formed in the same manner as those described just above. However, they have a very dense clay subsoil at six to eighteen inches be- low the surface. This subsoil is almost impervious to water. When the surface layer has been saturated, any additional rainfall runs off. Consequently, soil ero- sion is apt to be very serious when this type of soil is cultivated. Sof f Texture Light soils erode more easily than heavy ones when surface runoff occurs, consequently more skill must be used in farming them. When light soils are util- ized they should in general be deeper than heavy soils because they supply less moisture per foot of depth to growing crops. Steepness of Slope It is usually desirable to make contour plantings on soil that has a slope or fall greater than 2 to 4 feet per hundred feet. Stated another way, any soil that is apt to wash or erode during winter rains should be contour planted. It is usually impractical to make contour plantings on soil that has a slope of more than 15 or 20 feet per hundred feet because the soil erosion hazard increases with the slope. SEE PICTURES OF GOOD AND BAD HILLSIDE PLANTINGS ON THE PAGES THAT FOLLOW I [5] THIS ORCHARD WAS COiffOUf PiMtCd ^ This apple orchard was planted on the contour about twelve years ago. The rows in the picture curve around the hill. In the up-and-down-hill direction the rows are straight. This arrangement permits contour and up-and-down-hill cultiva- tion. The early spring cultivation will be on the contour; and a later cultivation, after the last heavy rains, will be up and down hill to remove the narrow strip of cover crop left in the contour rows. The cover crop in the picture is volunteer an- nuals and has been fertilized enough to produce a good growth. As an added precaution, annual ditches have been plowed as shown. Such ditches carry off water that does not sink into the ground, especially in short periods of very heavy rainfall. These particular ditches empty into a concrete pipe. An inlet is shown at the end of the ditch in the foreground. Orchards planted and cared for as this one will last for a long time as far as soil erosion is concerned. THE ROWS CURVE AROUND THE HILL ANNUAL DITCHES HAVE BEEN PLOWED THE VOLUNTEER COVER CROP HAS BEEN FERTILIZED tg^Mmlm^:, m^^:^^r^-^ •1 ^ THIS ORCHARD WAS S^UttfC PldHtCd This apple orchard was square planted about thirty years ago. In the foreground the slope is six or seven feet in 100 feet. SOIL EROSION HAS LEFT TREES STANDING ON MOUNDS A NUMBER OF TREES HAVE DIED THIS UNFERTILIZED VEGETATION CANNOT PROTECT THE SOIL This picture, taken in the early spring of 1948 following a very dry winter, does not show any erosion as having occurred during the winter just past. There is abun- dant evidence that soil erosion in previ- ous winters has been very serious. The trees in the foreground are on mounds, some of which are a foot high, indicating the amount of soil loss between the rows. There are several blank spaces where the trees have died. Trees in the left background on a flatter slope have not been injured by soil erosion and are still in good condition. The only cover crop is a little unfer- tilized vegetation that would have been inadequate to protect the soil against ero- sion in a normal winter. [7] ♦»>«, :'&i'j-h'kxmd--''^m'U,Si^^mmi THIS IS THE RESULT OF Up^aiid^dowii^mn Culthathn This vineyard is losing large amounts of soil by erosion. It |^ is probable that as much as a foot of soil has eroded from ^r the surface. Most of the vines are replacements. Some are mature, v/hile others have just been planted. Some of them may actually have been washed out. Note the almost complete absence of cover crop. [8] CrosS'S/ope Cutiivaiion IS ONLY A PARTIAL SOLUTION 4 This vineyard was planted so that it could be cultivated across the slope. Although not a true contour planting, no serious soil erosion has resulted from cross-slope cultivation. HERE IS THE DANGER WITH THIS METHOD: Under slightly less favorable conditions the water might have run down the rows each way to the depression in the center of the picture, and thence straight down the depression to cause gullying. Had the rows been curved to fit the hill this hazard would not be present. The fairly good cover crop helped prevent erosion. THE Ri^ht Kind Of HILLSIDE PLANTING ww^. y/'/rli >>,v' ^-'.*' di^iiigi^. ?^M^ T ^ These berries have been planted up and down the slope in straight rows. A planting in this condition is subject to serious soil erosion if a rain should occur. Having been planted this way the only thing to do is to plant a cover crop and hope that it will save the planting. This hazard could have been avoided by contour planting. [10 ^m Bush berries have been planted on the contour on a ^ hillside formerly covered with brush. The first spring cultivation to dispose of the cover crop has just been com- pleted. Many areas of good soil like this can be found in California. When planted and cultivated in this manner the soil will be safe from erosion. THE (KrO/9^ AfVWif OF HILLSIDE PLANTING im: Soil MdildjCmCilt for perennial UNIRRIGATED CROPS PLANTED ON THE CONTOUR Cover Crops A natural vegetative cover is one of nature's ways of protecting steep soils from erosion. If she had not been able to protect them in this manner, the soil would not be there today. Therefore, our most promising method is nature's— a cover crop. Cover-crop seed should be planted early in the fall so that a good ground cover may become established before cold weather. If necessary, fer- tilizer should be used to secure a good growth. ^ Annual Difches In cases where a cover crop will not prevent soil-eroding runoff, annual ditches may be used to carry off water that does not soak into the soil. Annual ditches are made between rows with a mouldboard plow throwing the furrow slice downhill (see page 7) . These ditches should be spaced close enough so that the soil between them does not erode. Factors such as steepness of slope, rainfall inten- sity, lightness or kind of soil, and condi- tions of cover crop, have to be taken into account in determining the distance be- tween ditches. Where the erosion hazard is great, it may be necessary to have an- nual ditches in each orchard row or about every 25 feet. When these ditches are carrying large amounts of water they should be patrolled in order to stop breaks before they become serious enough to start gullying. CuftfVcfffon Much money is wasted in unnecessary cultivation. Under conditions of contour planting, the three main purposes of cul- tivation are: 1. To kill the cover crop in the spring so that it will not use moisture that the crops need. 2. To work the cover crop into the surface soil so that it will not be a fire hazard. 3. To maintain a trashy surface which is resistant to soil erosion in case late rains occur. The first disking of the cover crop should be done after the heavy winter rains, but before the cover crop takes too much moisture from the soil. For fruit trees this first disking is usually about blossomtime. However, no set rule can be given. Experience and good judgment must be the guides. Later, cultivation should incorporate the cover crop into the surface few inches of soil so that it will not be a fire hazard during the sum- mer. Generally speaking, no further cul- tivation is needed. faff Cultural Operations From a soil erosion standpoint the last working of the soil before the rainy sea- son is very important. After crop harvest, wagon tracks or other implement marks can usually be found running up and down hill which, if not removed, may cause gullying. These marks should be destroyed by any one or all of the follow- ing operations: contour cultivation; con- tour planting of fertilized cover crops; and, installation of annual ditches. ] HOW TO Lay Out a contour planting size up the Land tor Outlets: Laying out a contour planting takes a little more judgment and ingenuity than the usual square planting. Pictures on previous pages give an idea of what a con- tour planting looks like. It is probable that your county farm advisor can direct you to a nearby contour planting. An examination of such a planting will prob- ably furnish some practical ideas. When an area is proposed to be con- tour planted it should be sized up for outlets for runoff water discharged from annual ditches. In general, outlets should be provided so that water will not run more than five or six hundred feet in annual ditches. Occasionally annual ditches may be longer than this but ex- perience indicates that the maximum length suggested is most practical. There- fore, outlets or drainageways to carry water discharged should be provided ap- proximately every five or six hundred feet. Frequently, satisfactory drainage- ways can be found at about twice this interval, or about 1,000 or 1,200 feet apart. In this instance plantings can be made so that annual ditches can be sloped each way to the outlets from a point ap- proximately halfway between the outlets. Three Ways to Provide Outlets 1 . By the use of natural gullies or swales. When this method is used it is very important to protect the outlet so that serious soil erosion will not occur. In shallow gullies or swales a sod cover will usually be sufiScient. Almost any grass or plant that will grow well locally can be used to form a sod. This sod strip will provide a permanent, noneroding chan- nel and should not be cultivated or other- ^^ wise disturbed. If a gully is used for an outlet, it will probably be necessary to use some small, inexpensive dams to check the flow of the water. The dams can be made of rocks, pickets and brush, or, if the expense is justified, of masonry or concrete. When these dams are com- plete the gully should be seeded insofar as practical in the same manner as the shallow gullies or swales mentioned above. 2. By releasing excess water on natural vegetation at edge of field. Occasionally annual ditches can be carried into natural vegetation adjoining the planted field where the excess water can be released safely. It is important to end the ditches so that the water from several of them will not be concentrated into one stream and cause gullying. 3. By artificial outlets, such as concrete pipe or wooden flumes. These outlets are rather expensive and should only be used when the two meth- ods just described are impractical. Con- crete pipe is usually preferable to wooden flumes, because it is permanent and is buried out of the way. [13 Lay out the Rows After the general layout has been de- termined the actual location of the rows is undertaken. Assume a side hill on which two swales or gullies 1,000 feet apart are to be used for outlets. Select a starting point approximately midway be- tween the outlets where the land has an average slope. At the lower edge of the field start measuring up the slope, driving guide stakes where each row of trees or vines will be. Then from each of these stakes lay out a row of guide stakes toward each gully with a fall of about 1% feet per hundred feet of length. Guide stakes should be placed frequently enough so as to establish a row line which is usually curved. Occasionally, on uneven land, the guide stakes may need to be as close as 25 feet, but usually 50 or 100 feet will be close enough. If the row locations, as now indicated by the guide stakes, are not about the same distance apart, slight adjustments can be made to facilitate the future use of cultivating equipment. This diagram shows a piece of land suitable for contour planting. It is bounded on the top by a fenced, wooded pasture, on the sides by stabilized watercourses, and on the bottom by an orchard. Each stake indicated by • locates one point in each row to be staked out. Stakes indicated by X's show the location of the proposed rows of trees. Each of these rows slopes about 11/2 per cent, or 11/2 feet for each 100 feet of row, from the stake toward the watercourse. [14] locate the Trees After the rows have been determined, the position of the individual trees or vines is marked with a location stake. In orchards and vineyards there are two methods of locating the trees or vines; (1) by spacing them at uniform inter- vals along the contour row line, or (2) by locating them in the contour row line so that they also make straight rows up and down the hill. The second method allows up-and-down-hill cultivation when desirable. Since berries are trellised, the first method is appropriate for them. Q " .. ^^h jfoOGOOOOOOOOO ooo ''goooooogooo o ooo This diagram shows the piece of land completely staked out and ready to plant. Two planting methods are shown. At right, the field has been staked to show how it may be cultivated up and down hill in addition to the contour cultivation. At left, the field has been staked with the trees equidistant in the rows, permitting only contour cultivation. Furrows can be plowed between the contour rows in order to drain excess runoff water to the watercourses. [15 CfUffiifieai YOU WILL NEED Before starting to lay out the con- tour planting, provide yourself with these items: Level Rod Tape Hand Ax Guide Stakes Location Stakes Some of these items are available in several different types. The following dis- cussion is to aid in selecting equipment best suited to the particular job. Levels of several types may be used: an engineer's level, a builder's level, a farm level, or a hand level. The builder's level is considerably cheaper than an en- gineer's level and is very satisfactory for this type of work. A hand level may be used, but considerable skill is needed to obtain sufficiently accurate results. A rod with a target is used in locating the rows so that they have the proper fall or grade. Engineer's leveling rods are available in different lengths, and col- lapsible to various lengths. One made up of shorter lengths is easier to carry in a car. Another less-expensive type is known as the flexible rod. On this rod the gradu- ations are printed on a strip of fabric. The fabric is tacked on a 1 x 3-inch board about 12 feet long. A target cannot be used on this type of rod, however, it is a very practical piece of equipment. Tapes are used for measuring dis- tances. Two engineer's steel tapes are in common use; one is wound on a reel and the other is done up by hand. Several less expensive types of tapes can be used sat- isfactorily, but they are not as durable as the steel type. A hand ax is used to sharpen and drive stakes. Guide stakes are used to indicate the general position of each row. They can be made from material about one inch thick, two inches wide, and 2% feet long. The upper end should be whitewashed. Location staices are used to show the exact location of each tree or vine to be planted. They can be made out of mate- rial about the size of a lath and about eighteen inches long. If the upper end is whitewashed, they are easier to see. Costs. In order to give a general idea of what some of these items cost, the fol- lowing approximate figures are given as of January, 1948: Levels: builder's level with tripod $135, farm level with tripod $31, hand level with leather case $8. Rods: engineer's rod with target $30, flexible fabric rod 11 feet long $2. Tapes: engineer's steel tape 100 feet long on reel $20, steel tape 100 feet long in leather case $15, metallic tapes 100 feet long in leather case $13. From these figures it can be seen that the least expensive of these three items will cost about $23, while the most expensive will cost about $185. The amount spent will be deter- mined by the usage expected from the equipment. Cooperative Extension work in Agriculture and Home Economics, College of Agriculture, University of California, and United States Department of Agriculture cooperating. Distributed in furtherance of the Acts of Congress of May 8, and June 30, 1914. C. W. Rubel, Acting Director, California Agricultural Extension Service. 15m-5,'49(B3494) [16