Division of Agricultural Sciences UNIVERSITY OF CALIFORNIA "'"^O PRODUCTION OF RANGE CLOVERS LESTER J. BERRY CALIFORNIA AGRICULTURAL Experiment Station Extension Service CIRCULAR 458 Planting CLOVER CRIMSON SUBTERRANEAN BUR Clovers have a high feed value They grow in most California cli- mates and soils ... do well on brush burns, annual type ranges, grainland . . . provide plentiful feed in spring . . . and make good dry feed in summer and fall. Four sturdy and widely-adapted clovers . . . can be grown on livestock ranges to give your cattle improved for- age. Prolific seed producers, they draw nitrogen from the air and thus enrich the soil. This circular . . . tells how you can use one or more of these four clovers — rose, crim- son, subterranean, bur — to im- prove rangeland. It tells how to seed, fertilize, and manage them. Details on each clover are in the second half of the circular. THE AUTHORS: William A. Williams is Assistant Professor of Agronomy and Assistant Agronomist in the Ex- periment Station, Davis. R. Merton Love is Professor of Agronomy and Agronomist in the Experiment Station, Davis. Lester J. Berry is Agriculturist in the Agricul- tural Extension Service, Department of Agron- omy, Davis. JANUARY, T957 [2] can improve your rangeland forage Yo .ou can use annual reseeding clovers to provide an abundance of nutritious feed during the spring season and good dry feed during the summer and fall. Rose, crimson, subterranean, and bur clovers are winter annual legumes. They germinate with the first substantial fall rains and grow slowly during winter. When the temperature starts to rise in late winter they begin rapid growth. The clovers bloom and set seed in late April and May. Then the plants dry and cure, casting their seeds which remain dor- mant until the fall rains begin. This pattern of growth makes these clovers particularly well adapted to California's climate of relatively warm, moist winters and hot, dry summers. Among the four of them, these clovers do well over a wide range of soil types at elevations up to 3,000 feet and with an annual rainfall above 10 inches. They are prolific seed-producers under aver- age conditions and usually produce some seed under quite unfavorable conditions. Consequently, after they are established, reasonable care assures their continuing on the range practically indefinitely. Nitrogen from the Air These legumes are able to supply their own nitrogen from the air in the pres- ence of the proper legume bacteria. This trait is particularly desirable in Califor- nia, where almost all range soils do not contain enough nitrogen for abundant forage production. The nitrogen ob- tained from the air not only makes the clovers productive but also increases their protein content. It also improves the amount and quality of feed produced by other plants growing with them. These four clovers are well adapted for use in seeding annual-type range as well as abandoned grainland. On brush burns, rose clover — and in some cases one or more of the other clovers — should be included in the seed mixture. The clo- vers have also been successfully seeded with oats and barley under favorable moisture conditions. They furnish valu- able forage in the grain stubble after harvest and during the following years. Mixtures of annual clovers and peren- nial grasses on the better sites will lengthen the season of use by providing green feed earlier in the fall and later in the spring. Such dryland pastures make an ideal supplement to unimproved range. Fertilization Is Important Soil fertility is an important factor in obtaining high production from the clovers. The two fertilizer elements that improve range legume growth most fre- quently are phosphorus and sulfur. More than three-quarters of California's foot- hill and terrace soils are deficient in phosphorus, and these make up the bulk of our range soils. The precise area needing sulfur is not known since more soils deficient in sulfur are now being identified. Extensive areas of sulfur-de- ficient soils lie along the eastern edge of the San Joaquin Valley and the western border of the Sacramento Valley. Some soils need both phosphorus and sulfur. Single superphosphate is a good remedy for these since it contains substantial [3] 700 How fo clovers ur fields seeded with annual responded to phosphorous fertilizer. 600 0 (Fields harvested May 22-27, 1953) 150 Lbs. Treble super- phosphate in fall of 1952 o | 500 Same as Field No. 2 -Q "f 400 8 "§ 300 - 200 Lbs. Single super- phosphate in fall of 1951 150 Lbs. Single super- phosphate in fall of 1952 Protein 1 8 8 Check | Check Check Field No. 2 Field No. 3 Field No. 4 Field No. 5 amounts of both (18-21% P205 and 10- 12% S). The benefits from phosphate fertiliza- tion of the clovers are illustrated by ex- periments performed on a red claypan soil (Placentia series) near Lincoln, Placer County. Inoculated rose, crimson, and subclover were planted just prior to fall rains. In three fields single super- phosphate was applied at the rate of 150- 200 pounds per acre and in another treble superphosphate was applied at the rate of 150 pounds per acre. On the 498 acres improved in this manner, the carrying capacity was tripled in the following three-year test period. The increase in feed resulting from phosphorus fertilization is shown in the chart above. Protein contained in the feed was increased by two times in field 3 and up to nine times in field 4. This resulted from both the greater amount of feed produced and the in- crease in the protein percentage, from 9.0 per cent unfertilized to 13.1 per cent fertilized. The phosphorus content of the feed was also improved. Sulfur Improves Forage on Rose Clover Ranges Treatment Forage produced (dry basis) lbs. /acre Per cent rose clover in forage Per cent protein in forage 1954 1955 1954 1955 1954 1955 Resident Range (Filaree) Unfertilized 500 lbs. /A. Gypsum . 1,080 1,120 1,970 3,080 680 730 1,540 2,270 0 0 29 64 0 0 38 53 4.6 6.0 8.5 12.4 6.8 6.8 Seeded to Rose clover Unfertilized 10.1 500 lbs. /A. Gypsum 11.9 Data show how rose clover takes advantage of sulfur fertilization to increase forage production and protein on sulfur-deficient Snelling sandy loam in Stanislaus County. From a cooperative test with W. N. Hepelstine and R. J. Arkley. [4] The increased potential resulting from sulfur fertilization of adapted legumes on Snelling sandy loam is illustrated in the table on page 4. On this soil the volunteer range feed (mostly broadleaf filaree) produced an average of less than one- half ton of dry feed in the two-year test. Seeding rose clover doubled forage pro- duction. Fertilization of the rose clover seeding with 500 pounds of gypsum per acre increased feed as much again as did the rose clover seeding alone. Applying gypsum to the filaree range did not in- crease feed production appreciably. In- troducing rose clover improved the pro- tein content of the feed markedly, and gypsum fertilization further improved it. As a result of these and other tests, over 360 acres on this ranch have been simi- larly improved. The results not only show how important sulfur fertilization can be on specific soils, but also how im- portant it is to have a plant such as rose clover which can take advantage of the improved fertility. Fertilize at Time of Seeding For the majority of range soils, from 200 to 500 pounds of single superphos- phate will aid the establishment of range clovers. This material contains both phosphorus and sulfur. In areas where sulfur is the principal nutrient lacking, 200 to 400 pounds of gypsum per acre will satisfy the plants' needs. In areas of poor native growth the addition of 10 to 20 pounds of actual nitrogen per acre is helpful. See your local University of California Farm Advisor for information on soil nutrient deficiencies before decid- ing on the kind and amount of fertilizer materials to be used. Range clovers should be refertilized every two or three years. Local experi- ence will best determine the amount of fertilizer necessary to maintain a pro- ductive stand of clover. This grain drill was used for placement of seed and fertilizer on a ranch in San Diego County. (Photo by Charles F. Walker) [5] Seed and Fertilizer Placement Within the past six years considerable information has been published concern- ing the success of Eastern experiments with the placement of fertilizers in pas- ture seedings. The practical importance of these principles is being tested in California. The placement procedure consists of banding the seeds over drilled rows of fertilizer. This method has several ad- vantages over broadcast methods. The emerging seedlings have immediate ac- cess to nutrients which may otherwise be unavailable in the soil, or if broadcast, may be scattered out of reach. Also, con- centrating the fertilizer near the seed places it out of reach of many of the competing plants between the rows. Maximum efficiency is obtained by row placement of phosphorus fertilizer, much of which becomes fixed by soil colloids when broadcast and therefore unavail- able to plants. Various pieces of equipment have been used to achieve the same basic results. The simplest of these consists of an in- expensive modification of a grain drill with a fertilizer attachment and a grass seeder box. The fertilizer is dropped through the furrow openers as is com- monly done when sowing grain. The fur- row openers are set to deliver the ferti- lizer 1 to 2 inches below the surface of the closed furrow in rows 12 inches apart. The range seed mixture is then conveyed by tubing from the grass seeder box and dropped on the closed furrow 8 to 12 inches behind the fertilizer shoe. The seed is dropped from a height of about 3 inches so that the seed is con- centrated in a band on the surface of the closed furrow and is either covered by subsequent rolling, press wheels, or drag chains. Inexpensive conversion kits for grain drills are available commercially. Seedbed and Seed Coverage Seedbed preparation is desirable whenever possible prior to planting clo- vers on rangeland just as it is with culti- vated crops. It serves two purposes. It helps to eliminate competing plants which volunteer in all grass and wood- land grass range plantings, and it pro- vides the loose soil necessary for cover- ing the seed. Volunteer annual grasses and forbs grow faster than clovers under normal winter temperatures. This makes them strongly competitive with the clovers. Disking or plowing deep before fall rains will bury the seed crop of these volunteer weedy species. Disking after the first rains will destroy any germinating volun- teers. Where competition is not likely to be severe a light single disking 1% to 2 inches deep is sufficient to provide a surface mulch and seed coverage. This light disking will disturb only a portion of the sod, thus reducing the risk of soil washing in the winter. Sudangrass has been used success- fully as a cleanup crop prior to planting clovers. Since sudangrass is planted late in the spring, volunteer vegetation must be turned under prior to seed formation. Sudangrass exhausts soil moisture in the early summer, thereby preventing sum- mer weeds from making any headway, and furnishes nutritious summer feed. Clover seed should be drilled into the sudan stubble without seedbed prepara- tion. The reduced competition, the firm seedbed, and the protection of the stub- ble are ideal conditions for clover estab- lishment. Summer fallow can be used where moisture or other conditions are not favorable to sudangrass, Where seed is sown on sod or grain stubble it should be tramped in by livestock. Controlled burning of tall dense brush provides a desirable seedbed for clovers. Where such stands have been re- moved, remnants of grasses and weedy species are sparse. During the first year, while the seeded clovers are establishing themselves, there is little or no competi- tion from resident plants, as there is with a seeding on the open range. In open [6] areas where, before burning, there was only grass or sparse brush, seeding is not likely to be so successful because of competition from volunteer plants. Al- though ash from burned brush provides some cover for broadcast clover seed, the ash is often blown away. Mechanical coverage is desirable where possible. Cover the seed during or following the planting operation on cultivated seedbeds to protect it from birds, ro- dents, and ants. This practice provides the seed with a good tie to subsoil mois- ture and helps the young root to pene- trate the soil. Clovers should not be seeded more than % inch deep. The de- sired depth may be obtained with a prop- erly regulated drill on most soils, with a cultipacker seeder, or by broadcasting on a firm seedbed followed by rolling. Time of Seeding October is the optimum month for seeding clovers over most of the area to which they are adapted. They make maximum use of the season's moisture when planted before the first fall rains. The clovers ordinarily contain hard seed which will germinate over a long time and protect against a prolonged drought following the first germinating rain. If your knowledge about the site indicates that competition from volunteer plants will counteract the advantage of early planting, then your best procedure is a light disking of a prepared seedbed after fall growth has started, followed by planting. Midwinter seedings have a chance of being moderately successful only during mild winters. In winters when heaving is a problem the early- planted clovers with vigorous root sys- tems are better able to withstand the strains developed by alternate freezing and thawing of the surface soil. Although some early spring seedings have been successful when late rains oc- curred, spring seedings of winter annual clovers ordinarily have little insurance of success on dryland. Where a limited amount of irrigation water is available, it can be profitably used in starting the clover earlier in the fall or in reducing the moisture stress of late winter or spring droughts. Inoculation Is Good Insurance Inoculation of the clovers with nitro- gen-fixing bacteria is good insurance for stand establishment. The proper strains of bacteria are frequently absent from the soil. Commercial inoculums cur- rently available are reliable sources of legume bacteria. Inoculation is done by placing the bacteria on the seed in a slurry just be- How inoculation boosts forage. Subclover at top was not inoculated, averaged 60 pounds forage per acre; inoculated seed below aver- aged 1,460 pounds per acre. [7] fore planting. Care must be exercised not to wet the seed so much that it won't run freely through the seeder. Inocula- tion is easily accomplished by the use of a small concrete mixer, but also may be accomplished by hand mixing with a shovel. The bacteria stimulate the roots into producing nodules in which the bacteria live. There they make free atmospheric nitrogen available to the plant. This process of nitrogen fixation by legumes produces high-protein forage, and im- proves the fertility of the soil as the le- gume roots die and decay. Legume bacteria are easily killed by sunlight, drying, and high temperatures. Therefore you should cover inoculated seed as soon as possible after sowing. Fresh inoculum must be used. Look for the expiration date on the container. Clover inoculum is used for rose, crim- son, and subclovers. Alfalfa inoculum is used for bur clover. Seed treatment with a fungicide may be profitable where seedling dis- eases are a problem in obtaining stands. However, many fungicides, particularly those containing mercury, destroy leg- ume bacteria when both are applied to the seed. When fungicide treated seeds are used, inoculation should be your last operation performed before plant- ing, and the interval between inoculation and planting should be as short as pos- sible. Seed treatment by fungicides does not interfere with inoculation by soil- borne legume bacteria. Grazing Management Timely grazing is essential to insure permanent stands of clovers. Newly- seeded areas should be grazed as soon as the weeds and annual grasses are of pasturable height. By that time the coty- ledons (seed leaves) of the clovers will have dropped off, and true leaflets will have formed. The plants will be 2 to 5 inches high. Graze the field to a uniform height of about 3 inches for a period no [ longer than a month. In many instances this has required as many as three cows and their calves per acre. Take care to prevent trampling damage if the soil is wet. It is almost impossible to harm a new seeding the first spring by "over-graz- ing." The important thing is to remove the stock well before the last spring rains to allow the seeded species to mature a seed crop. Graze the field again before the fall rains to trample the seed into the ground and so thicken up the stand. A weed-free seeding in the ash of a brush burn becomes better established if you keep stock off the first season until the seeds begin to shatter. Annual leg- umes do well in burned areas because there is usually no competition from resi- dent annuals. Where there is competition from annual grasses or sprouting brush, an early grazing is helpful. Long-term Grazing Program No fixed rules can be outlined for a range domain such as California's with its wide variations in climate, soil, and elevation. A grazing-management plan must be based on individual ranch con- ditions, type and abundance of forage plants and their distribution over the given area, and practical necessities such as cross-fencing and stock-watering fa- cilities. Obviously, the seasonal green feed produced by winter rains should be con- verted into meat and wool while at its best. On the other hand, the perennials and better late-maturing annuals (such as the clovers and soft chess) should be allowed to set some seed and thus in- crease their percentage in the total for- age. This requires a balanced grazing program. A three-year rotation plan has been found practical and effective in im- proving the range. In carrying out such a plan, the rancher divides his range area into three fields, either by fencing or by herding to keep stock from certain por- ] tions of the range. The plan must also include adequate watering facilities in each field. This is how it works: The first year, the rancher grazes field number 1 early, and removes the stock before the surface soil moisture is ex- hausted in the spring, keeping the ani- mals in the other two fields in turn. The second year, he applies the same treatment to the second field, using the first and third fields for later grazing. The third year, he applies this practice to the third field, turning the animals then into the first and second fields. Such a grazing cycle should serve to keep a proper balance of forage species in all three fields. The use of a mixture of annual clovers of varying growth habit allows a much greater latitude of adjustment of live- stock use than is otherwise possible. Hence the application of the above plan can be quite flexible for mixtures. Feed Value Is High The feed value of clovers is high com- pared to resident range feed especially in terms of their protein content. This is shown in the table on page 4 and in the table below. The protein content of rose clover is somewhat less than that of bur clover, as shown by the following figures: lush vegetative stage — rose 24.9 per cent, bur 27.0; flowering — rose 12.6, bur 15.0; and dead ripe — rose 8.0, bur 13.9. The protein content of crimson and sub- clovers does not differ consistently from that of rose clover when grown under comparable conditions. Clovers Grow on Grain Land All four clovers have been sucessfully grown in grain where seasonal moisture has been adequate. The clovers will not ordinarily grow as robustly when com- peting with cereals as when sown alone. But they provide a good aftermath feed to supplement the cereal stubble and they will volunteer in subsequent years, fur- nishing nutritious feed in the seasons when cereal is not sown as well as add- ing nitrogen to the soil to benefit subse- quent grain crops. The clovers should be planted after the cereal, otherwise they will be buried too deep. A Glenn County rancher seeds clovers by plane after a barley crop is harvested. Grazing sheep do an excellent job of "planting" the seed. Fertilizing with Phosphorus Increases Protein Treatment Per cent (dry basis) Forage Protein Fiber Fat Ash Nitrogen- free extract Phos- phorus Calcium Clovers Resident annuals Total feed Check Fertilizer Check Fertilizer Check Fertilizer 12.1 14.3 6.6 8.2 9.0 13.1 30.6 30.8 30.0 29.2 30.6 30.6 1.7 1.7 1.9 1.8 1.8 1.6 5.5 4.9 6.9 7.1 6.2 5.3 49.6 48.5 54.6 53.7 52.5 49.4 .098 .144 .103 .120 .099 .136 1.37 1.37 1.56 1.58 1.46 1.40 Data show effects of phosphorus fertilization on the composition (dry basis) of forage on range seeded with annual clovers. Average of 4 fields in Placer County. Forage was harvested in late May when clovers were mature but had not shattered. [9] Pest Depredation The depredations of pocket gophers, field mice, kangaroo rats, ground squir- rels, rabbits, harvester ants and birds can severely affect initial establishment as well as subsequent maintenance of stands of clovers. These pests can be controlled by appropriate methods, but the eco- nomics of control under range condi- tions are still in the experimental stage. Clovers for Range Improvement Annual reseeding clovers can provide your cattle with an abundance of nutri- tious feed during the spring season, and good dry feed during the summer and fall. Mixtures of annual clovers and per- ennial grasses on the better sites will lengthen the season of use by providing green feed earlier in the fall and later in the spring. Such dryland pastures make an ideal supplement to unimproved range. Additional fall and winter green feed can be made available on native range by the application of fertilizer in the fall, using nitrogen alone, or in com- bination with phosphorus and/or sulfur depending on the particular soil. Rose Clover . . . has proved to be the most widely adapted legume for range use in Cali- fornia. It will grow on soils where many other forage plants do not survive, and will even provide some forage under such unfavorable conditions. Since its introduction from Turkey in 1944, it has been planted on many thousands of acres. How It Looks Rose clover, Trifolium hirtum AIL, is a much branched, winter annual legume that grows 3 to 18 inches high. The spreading branches are densely covered with short, coarse hairs. Each leaf has three leaflets with a scattering of hairs over both surfaces and usually a small reddish mark a little above the center with a whitish mark flaring to the leaflet margins. The flower heads are rose- colored, spherical, about % inch across, and profusely hairy. The plant normally has an upright growth habit. The seeds are yellow, smooth, a little over %6 inch UNIFOUATE LEAF long, and almost spherical in shape. The number of seeds per pound is 140,000. It Is Widely Adapted It is adapted to a wide range of soil texture and soil depth. It does well on strongly acid to moderately alkaline soil conditions but does poorly on water- logged soils. Being a winter-growing an- nual it escapes summer drought. Com- mercial plantings succeed down to 10 inches annual rainfall. Since it blooms later than other annual clovers, it ex- tends the green feed period. Climatically it is adapted to most of the range area of the state. Exceptions are found in the coastal fog belt, in areas receiving less [10 than 10 inches annual rainfall, and above 3,000 feet elevation. Livestock Like It Cattle, sheep, and deer graze rose clover well even when it is completely dried up. It is also well liked by dove and quail. Rose Clover Reseeds Itself An abundance of viable seed is pro- duced by rose clover. Even under un- favorable conditions some seed is usually produced. One fall seeding establishes the crop. It then reseeds itself in subse- quent years, increasing in density and production. A high percentage of each year's crop of seed is hard. These hard seeds do not germinate with the first fall rains, but remain dormant for a variable extended period of time. Sometimes a large portion of them do not germinate until the second year after production. Hard seeds provide insurance against stand-killing droughts or frost heaving after germinating rains. After a sufficient supply has built up in the soil it will tide the clover over a year of cultivation for a grain crop, or a year when the bloom- ing clover is grazed or harvested for hay. Percentages of hard seed in several samples of commercial rose clover seed are shown in the table below. A livestock management practice fa- voring reseeding of rose clover is the removal of stock while enough soil mois- ture remains to make a seed crop, fol- lowed by summer grazing of the dry clover to shatter the seed and trample it into the soil. Plant It on Annual Type Ranges Use from 1 to 10 pounds of seed per acre. Drill or broadcast the seed. If you are not in a hurry to get a stand, use the lower seeding rate. An original seeding of 1 pound per acre will generally de- velop into a solid stand in four or five years. The higher rate should provide a solid stand the second year. Depth of planting should not exceed % inch. If the soil is extremely infertile and supporting practically no growth of native plants, use rose clover alone. If there is a fairly good cover of native weedy annual grasses and other types, use a mixture of 50 per cent rose clover, 25 per cent subclover, and 25 per cent crimson clover. ( Bur clover is not recom- mended in this original mixture because if it is not already present on a range it is probably not adapted to the soil con- Hard Seed Percentage in Rose Clover Seed Samples Analyzed by the State Seed Laboratory Year 1953 1954 1955 Average (20 samples) Highest hard seed content Lowest hard seed content . Average (7 samples) Highest hard seed content Lowest hard seed content . Average (7 samples) Highest hard seed content Lowest hard seed content . Hard seed Germination 32.90 53.75 58.00 39.00 15.00 42.00 28.00 57.43 56.00 37.00 17.00 69.00 35.86 51.00 47.00 45.00 25.00 57.00 Total 86.65 97.00 57.00 85.43 93.00 86.00 86.86 92.00 82.00 [11] ditions existing in that particular an- nual type range.) A mixture of winter annual legumes is desirable for two reasons: (1) Sea- sons vary tremendously in California, and rose clover may do better one year, and subclover another, on the same site. (2) Any field has some soil variation, and rose clover will occupy the poorer soil or better drained areas, while sub- clover will do well on the better soil or moister sections. Do not be concerned if the field looks very weedy the first year. This is the re- sult of the initial cultivation, which en- courages weed seed germination. The field will take on a cleaner appearance each succeeding year if livestock use is handled as recommended. On Brush Burns Include rose clover in the seeding mix- ture. It grows in the shade of tall grasses. No other range legume has proved to be so well adapted to such a great va- riety of soil types and climatic condi- tions. Use 1 to 2 pounds of seed per acre. This is usually adequate when included in a general seed mix, such as harding, smilo, other annual clovers, and alfalfa. Inoculate the seed with a general clover Rose clover seeded in a brush burn in Tulare County— elevation 3,000 feet. inoculant just before mixing with other seeds. Rose clover, except in the early bloom stage, has some tolerance for sprays which may be used on brush seed- lings following brush clearance. On Greenland Rose clover has been seeded success- fully with oats and barley in many field seedings where seasonal rainfall has been sufficient. For planting rose clover with a cereal, use 1 to 10 pounds of rose clover seed per acre. There are two common methods for planting: (1) seed the cereal first, then seed the rose clover by air- plane; or (2) have an alfalfa seed box attached to the grain drill and seed the cereal and clover at the same time. Care should be taken not to bury the clover seed too deep. The advantages of growing rose clover on grainland are: (1) It will do well on soil types that do not support a good growth of bur clover. (2) It will pro- vide a good aftermath feed to supple- ment the cereal stubble. (3) It will vol- unteer in succeeding years and add nitro- gen to the soil, thus aiding the grain crop. On Abandoned Grainland Give rose clover the same treatment as that described for annual type ranges. Trials and experience generally through- out the state indicate that, to date, rose clover is the best winter annual legume to use to reclaim such land. Gradually it builds up the soil to the point where it will support more and more growth of desirable forage plants. A striking example is a ranch in Santa Clara County where the soil had become very thin, and would not support vege- tation. The soil was improved through use of rose clover, which built up the depleted nitrogen supply. Summer annual weeds such as tar- weed, star thistle, and turkey mullein are controlled by vigorous stands of rose clover. As it matures it uses up moisture 12] Tarweed flourishes in freshly disked area at left. At right a six-year-old stand of rose clover has practically eliminated undesirable weeds allowing soft chess and annual ryegrass to invade the area. (Sacramento County) left by the earlier maturing annual grasses and thus leaves little for later ma- turing undesirable summer annuals. Rose clover has been unusually free of the insect and disease pests which fre- quently afflict other forage plants. It is resistant to the spotted alfalfa aphid. Seed is easily harvested directly by the regular combine seed harvester. Seed is retained in the head for an adequate time so harvesting may be delayed until well after ripening. Many ranchers have expanded their acreage of rose clover with home grown seed. Certified seed is available in quantity at moderate prices. Crimson Clover ... is a colorful winter annual legume and a heavy producer on much range land. Introduced into the United States as early as 1819, it is now widely grown throughout the Southern and Pacific Coast states. Its use in California has in- creased rapidly since it was first tested for dryland use in 1944. However, it is not adapted over as wide a range of dif- ficult conditions as is rose clover. How It Looks Crimson clover, Trifolium incarnation L., is an upright plant 6 to 30 inches high and has cylindrical heads about 2 inches long of bright crimson flowers. The stems and leaves are covered with soft hairs. The leaflets are usually un- marked although they occasionally have small dark-brown blotches next to the midvein. The seedling growth is slightly [13] more vigorous than rose clover, and its mature growth somewhat taller. It branches less and the individual plants cover less ground area than rose clover. The seed is yellow and shiny. Number of seeds per pound is 140,000, the same as for rose clover, but crimson clover seed is glossier and is shaped more like a football. Adaptation Crimson clover thrives on both sandy and clay soils. It is about as tolerant to acid soils as rose clover. It does not do well on poorly drained or highly alkaline soils. It requires somewhat more rain- fall than rose clover to survive, and con- sequently its range does not extend into desert conditions. It performs well on 15 or more inches of annual rainfall at elevations under 3,000 feet. On a Napa County ranch in the 20-inch rainfall zone, crimson clover has produced up to 9 animal unit months of feed per acre per year on a 210-acre field. This dem- onstrates its tremendous capacity to pro- duce under favorable conditions. Crimson clover is useful as a hay plant as well as for grazing. Its feed value is on a par with that of rose clover. Crimson Clover Reseeds Itself It produces an abundant seed crop much of which is usually hard seed. These hard seeds germinate over a period of time insuring a stand if unfavorable moisture conditions cause the early ger- minating seeds to die. The so-called "re- seeding" strains produced in the south- eastern states have been selected for a moderately high hard seed content for that reason. Livestock management fa- voring reseeding of crimson clover is the same as that for rose clover. Varieties Tests indicate that Dixie and similar "reseeding" varieties such as Autauga. Auburn, and Talledaga perform well in California. They bloom in the latter half of April and are one to two weeks earlier than the common crimson clover. Useful on Annual Type Range Crimson clover is most frequently used in mixtures with rose clover and sub- clover in the proportion of % to % of the total. It also may be sown in mix- tures in grain or in rotation with grain. It should be inoculated with the same inoculum as rose and subclover. 1 Hi ^ ■■■.■■;,..■■ ' . . . '-■■■■■-■■■■■ . ■ ■ J ; V A >;* Crimson clover in this Napa County field provides a growing ration for steers during the spring and summer months. [14] Diseases and Pests Sooty blotch is a foliage disease that infects crimson clover near the coast. Symptoms are dark spots on the leaves which cause leaf loss during blooming and lower the value of the forage. Slime mold has also been observed on seedling crimson clover, but apparently has not caused serious damage. Crimson clover is susceptible to the pea aphid and is considerably damaged under a heavy infestation. It is also sus- ceptible to the spotted alfalfa aphid. Seed Production Seed of crimson clover is easy to grow and harvest. The plant is upright and may be harvested directly or from the windrow when at the proper stage of maturity. Since the seed shatters rather readily, overmaturity causes losses. Com- mercial seed is readily available and moderately priced. UNIFOLIATE LEAF Subclover Subterranean clover, or subclover, is a low-growing winter annual with an unusual ability to plant its own seed by burying the seed heads in the ground. These characteristics make it very toler- ant to heavy, close grazing. Subclover was first introduced into California by the late Professor W. W. Mackie of the U. C. Agronomy Depart- ment with seed obtained from Australia. Plantings were established in 1933 on the Russ ranches in Humboldt County. These plantings are still in existence. Subclover has since proven to be well adapted to the coastal climate, and the acreage of subclover in production in Humboldt County alone has been esti- mated at over 20,000 acres. It also does well in mixtures in the Central Valley and adjacent foothills. Subclover has become the most valu- able dryland legume in Australia since the application of superphosphate to sub- clover pastures became a recognized practice in the early 1920's. Subclover is not a native to Australia, but was intro- duced accidentally from the Mediterran- ean region. Thus subclover travelled more than halfway around the world to reach California. How It Looks Subclover, Trifolium subterraneum L., is a prostrate winter annual legume that produces runners up to four feet long under favorable conditions. The runners and leaves are covered with short hairs. The leaf has three leaflets, each usually having a whitish crescent across it and frequently having many scattered black flecks over it. The flowers are usually in- conspicuous, occurring in groups of four creamy white or pinkish flowers. After flowering, the stalk supporting the head bends toward the ground, and the matured flowers turn backwards. At the tip of the flowering stalk a series of stiff forked bristles develop and reflex in turn. If the head is in contact with the soil at this time the bristles pull the seed head into the soil. The seeds are dark [15] purple, smooth, round, and about % inch in diameter. The number of seeds per pound is 65,000. Adaptation Available subclover varieties (Mt. Barker and Tallarook) are adapted to areas with 16 or more inches annual rainfall, and up to an elevation of 3,000 feet. It makes a very heavy growth in the coastal fog belt and is the most toler- ant clover to acid soil conditions. It makes substantial growth on soils hav- ing pH values down to pH 4.5. However, alkaline soils restrict the growth of sub- clover. In the Central Valley and ad- jacent foothill plantings with other an- nual clovers it is dominant in the moister sites, and forms an understory to the other clovers on the drier sites. Under intensive grazing it has been observed to become the dominant legume on the drier as well as moister sites. Subclover Reseeds Itself Of the annual clovers, subclover has the best reseeding insurance in its me- chanism for burying seed in the soil. For this reason it is difficult to graze out a stand of subclover. It is a prolific seed producer and a substantial amount of its production is hard seed. These seeds germinate over a period of time produc- ing a stand even though seed germinat- ing with the first rains die in a succeeding drought or freeze. Where subclover makes a lush growth, it reseeds better when grazed than when allowed to grow to the hay stage. This fact, however, is of no concern after two or three seasons of subclover production and a liberal supply of hard seed has been built up in the soil. Varieties There are a large number of strains of subclover varying widely in their growth habit and time of maturity. They can be grouped by maturity as early, midseason and late. The early varieties are stemmy, produce few leaves, and are poor forage producers, but are able to subsist in a short rainy season. Late va- rieties are leafy and good forage pro- ducers, but require a long rainy season. Midseason varieties are intermediate. Mt. Barker, the most commonly used variety in California, is a midseason variety with excellent vigor and forage- producing characteristics where rainfall is 16 inches or more. It is distinguished by a red collar at the base of the flower. Tallarook, the other commercially avail- able variety, is later and produces more forage than Mt. Barker. It has a green feed period two or three weeks longer than Mt. Barker under somewhat higher rainfall conditions. They are frequently sown together to use the advantages of each. The very early maturing variety, Dwalganup, has been tested extensively in California. It has not proven a satis- factory producer because of its stem- miness and lack of leaves. In 1941 a sheep fertility disease in West Australia was traced to a consumption of almost 100 per cent Dwalganup. When sub- clover consumption was reduced to ap- proximately two-thirds of the diet this trouble disappeared. No significant re- currences have been reported in the last 10 years. No sheep fertility problems at- tributable to subclover have been re- ported in California. Varieties of the early midseason ma- turity are currently under test in the more arid regions in order to extend the area of adaptation of subclover. Inoculation A number of areas have been observed in the state where subclover will not grow without being inoculated with appropri- ate legume bacteria* In these areas inoc- ulation, when used along with other proven production practices, can make the difference between stand failure and good forage production. Subclover should always be inoculated at the time [16 of planting. Once a stand has been suc- cessfully established, the bacteria will survive indefinitely as long as the sub- clover thrives. The legume bacteria group is the same as that used for rose, crimson, Ladino, red, alsike, and other true clovers (not bur, sweet or sour clovers). Mixtures Subclover is usually sown in mixture with rose and crimson clovers. A satis- factory rate is three pounds of each per acre. Along the north coast in the fog belt, rose and crimson clover are omitted, and orchard-grass or tall fescue or a mix- ture of the two may be included. Where hardinggrass is adapted the above clover mixture can be sown along with hard- inggrass at three pounds per acre. Some- times subclover is sown at the rate of five pounds as the only legume with hardinggrass. The perennial grasses sown with the legumes increase total pro- duction, lengthen the green feed period, and stabilize year-to-year forage pro- duction. Subclover Controls Range Weeds Medusa head, Elymus caput-medusae L., is a weedy unpalatable annual grass which has invaded much of our better foothill and coast range country. Seed- ing subclover has been observed to be the most successful means of controlling this undesirable invader. The recom- mended steps for medusa head infested range where cultivation is possible are: (1) plowing or discing the sod just be- fore seed is set; (2) phosphorus or sul- fur fertilizer as needed should be applied just prior to (3) fall seeding of sub- clover; (4) the newly seeded area should be grazed heavily for a short period in the early spring while any new medusa head is in the young leaf stage. Hairy oatgrass, Danthonia pilosa R. Br., is a weedy unpalatable perennial which has invaded areas of the north- coast range. Experiments show that it, too, is controlled by vigorous subclover growth obtained by the above procedure. Goatgrass, Aegilops triuncialis L., will probably respond to the same treatment also. ttl i Subclover pasture is good dryland milk producer in the north coast counties [17] Diseases and Pests No disease or insect depredations of subclover of consequence have been re- ported in California. It is not susceptible to the spotted alfalfa aphid. Seed Production Seed of subclover is more difficult to harvest than seed of rose or crimson clover since much of it is in the surface layer of soil. No seed is produced com- mercially in California at the present time. Most of the seed consumed here is grown in Oregon or Australia. In the customary harvesting method most of the top growth on seed fields is mown and re- moved. Then the runners and seed heads are loosened from the soil with a harrow and windrowed with a power rotary brush. The material is usually elevated and hauled to a stationary thresher. The seed may also be threshed directly from the windrow with a combine harvester. Vacuum harvesters have also been used successfully. Bur Clover . . . was brought into California during the Mission Period (1769-1824) and has since become widely established. It is an unusual plant in that it is an ag- gressive immigrant which has increased the value of our range lands. Most alien invaders have tended to decrease range values. The green bur clover of winter and spring as well as the dried plants and burs of summer are valuable high- protein feed. How It Looks Bur clover, Medicago hispida Gaertn., is not a true clover, but is an annual rela- tive of alfalfa. It may be distinguished from the true clovers (Trifolium species) by the unequal length of its leaflet stalks. The central leaflet stalk is longer than the two lateral ones of each leaf, whereas in all cultivated and most native true clovers the leaflet stalks are of equal length. The stems are much branched and prostrate although in a thick stand they may become erect. The plants are hairless. Each leaf has three leaflets which are unmarked. The flowers are yellow and occur in groups of 2 to 9. Seed pods usually have two or three flat coils with stiff hooked spines along the edges. Several varieties have been bo- tanically identified on the basis of the length of the spines. Commercial seed lots frequently contain a mixture of these, but the long spined type is the most prevalent. The seeds are kidney shaped, about %2 inch long, brownish- yellow in color, and the number of seeds per pound is 140,000. Adaptation Bur clover is adapted to most of the range in the state and volunteers widely, with the following limitations: It does not grow well on strongly acid soils nor under desert conditions, and it does not survive the winter at elevations much above 3,000 feet. Bur clover grows best on soils that have a good resident popu- [18] lation of redstem filaree. It is seldom present where broadleaf filaree domi- nates. The addition of phosphorus or sulfur to such soils does not favor the establishment of bur clover as it does rose, crimson, and subclovers. However, a heavy application of manure will help bur clover to establish on broadleaf filaree sites. Bur clover does not usually require seeding except where natural stands have been eliminated by cultiva- tion, weed sprays, or the encroachment of brush. Feed Value Outstanding Bur clover is an outstanding plant for its nutritive value at all stages of growth. Up to the bloom stage it usually contains above 20 per cent crude protein. As it matures the amount decreases as it does in all plants, but averages in the neigh- borhood of 15 per cent even when dry. In that stage animals consume the burs containing seed as well as the dry stems and leaves. This makes it a valuable sup- plement for other less nutritious range feed. Calcium and phosphorus are ade- quate, and digestibility is high even in the dry stage. Thus animals on dry feed that contains substantial amounts of bur clover make good gains. Diseases and Pests Diseases are not a serious problem in bur clover production. However, two in- sect pests are important. The clover-seed chalcis fly, which attacks alfalfa and red clover seed, also seriously damages bur clover seed. Estimates of seed damage have run as high as 75 per cent. No eco- nomical control is available for use against this insect on the range. It does not harm the forage. The spotted alfalfa aphid, which has recently caused so much damage to irri- gated alfalfa in California, also attacks bur clover. The seriousness of this threat to range forage production is not known at present. Seed Production Until recent years much of the bur clover seed produced was harvested as an impurity with barley and other grain crops. Since the hormone-type weed sprays have come into widespread use in grain fields, this source of seed has been largely eliminated. Now bur clover is harvested from pasture lands where there is practically a pure stand. When a harvester is used the crop must be cut and cured carefully before all of the seeds are ripe, since the burs ripen over an extended period of time and drop off readily when ripe. Where suction type harvesters are used the crop is permitted to completely ripen before harvesting. Then the burs are easily lifted by the suction. Seed of bur clover is available com- mercially, but the cost is often rather high. Co-operalive Extension work in Agriculture and Home Economics, College of Agriculture, University of California, and United States Department of Agriculture co-operating. Distributed in furtherance of the Acts of Congress of May 8, and June 30, 1914. George B. Alcorn, Director, California Agricultural Extension Service. 20m-l,'57(C2196)RMB [19] ^J f, AGRONOMY TRAINING leads to many careers AGRICULTURAL INDUSTRIES RESEARCH ORGANIZATIONS GOVERNMENT AGENCIES FARMING Agronomy deals with the production and improvement of field crops, pastures, and rangelands. Agronomic crops are grown on more than half of California's agricultural land. Trained agronomists are needed to produce more foodstuffs. handle speciality crops. develop improved varieties. devise and apply scientific methods. Training at Davis has special advantages: Instructors who are leaders in their fields, and are active in research on today's farm problems. The University farm, for practice and ex- periment in one of the nation's richest farm areas. Modern facilities, for better study and re- search. An uncrowded campus, with many new buildings. Letters and Science college on the same campus, broadening the scope of education. FOR FURTHER INFORMATION on agronomy write to Maurice L. Peterson, opportunities chairman, agronomy depart- ment. on entrance requirements on college opportunities write to Howard B. Shontz, office of the registrar. see your County Farm Ad- visor for college entrance counsel. CAREERS IN farm management farm operation seed processing seed marketing agricultural industry farm supply houses farm service houses teaching research Agricultural Extension Service crop improvement associations departments of agriculture University of California • Davis, Calif. STUDY INCLUDES management adaptation plant breeding culture utilization processing of cereals oil crops cotton sugar beets beans hay crops range plants irrigated pastures distribution variety improvement soil management weed control crop diseases animal husbandry agricultural machinery