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Trifolium pratense L.

Red clover, Peavine clover, Cowgrass

Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.

  1. Uses
  2. Folk Medicine
  3. Chemistry
  4. Description
  5. Germplasm
  6. Distribution
  7. Ecology
  8. Cultivation
  9. Harvesting
  10. Yields and Economics
  11. Energy
  12. Biotic Factors
  13. References


Extensively grown for pasturage, hay and green manure, considered excellent forage for livestock and poultry. Compared with alfalfa, red clover has about two-thirds as much digestible protein, slightly more total digestible nutrients, and slightly higher net energy value. The best approximation to vegetable boullion I ever made consisted of red clover and chicory flowers, boiled vigorously with wild onion and chives. Red-clover flowers are reported to possess antispasmodic, estrogenic, and expectorant properties. The solid extract is used in many food products, usually at less than 20 ppm, but in jams and jellies, it may be 525 ppm (Duke, 1984b).

Folk Medicine

Said to be used for: alterative, antiscrofulous, antispasmodic, aperient, athlete's foot, bronchitis, burns, cancer, constipation, diuretic, expectorant, gall-bladder, gout, liver, pertussis, rheumatism, sedative, skin, sores, tonic, and ulcers. Flowers have been used as a sedative. Russians recommend the herb for bronchial asthma. Chinese take the floral tea as an expectorant. Kloss recommends that every family "stash" red clover blossoms, gathered in summer, and dried on paper in shade. "Use this tea in place of tea and coffee and you will have splendid results." This is one of Kloss' diets that doesn't offend me. Pages have been devoted to the anticancer activity of the floral tea, a remedy not yet tested by the National Cancer Institute. Herbals recommend clover for bronchitis, leprosy, pertussis, spasms, and syphilis. Jason Winters tea, containing red clover and chaparral and some unidentified secret spice, sells at rather high prices as a "cancer cure" (Duke, 1984b).


Seeds are reported to contain trypsin inhibitors and chymotrypsin inhibitors. Green forage of red clover is reported to contain: 81% moisture, 4.0% protein, 0.7% fat, 2.6% fiber, 2.0% ash. Hay of red clover contains 12.0% moisture, 11.8% protein, 2.6% fat, 27.2% fiber, and 6.4% ash. On the basis of more than 500 analyses, Miller (1958) reported the hay contained on a moisture free basis: 8.3–24.7% protein (avg 14.9%), 1.0–6.6% fat (avg. 2.9%), 12.5–39.3% crude fiber (avg. 30.1%), 3.1–14.0% ash (avg. 7.9), and 33.4–59.1% N-free extract (avg. 44.2). For green red clover forage he reported 12.4–34.87. protein (avg. 18.2), 3.2–5.9% fat (avg. 4.0%), 12.7–30.8% crude fiber (avg. 24.2), 7.0–13.6% ash (avg. 8.8), and 37.1–49.7% N-free extract (avg. 44.8%). The hay (dry matter averaging 87.7%) contained 0.97–2.29% Ca (avg. 1.61), 0.09–0.45% P (avg. 0.22), 0.57–2.67% K (avg. 17.6%), 0.24–0.81% Mg (avg. 0.45%), 0.001–0.185% Fe (avg. 0.013%), 9.9–17.6 ppm Cu (avg. 11.2 ppm), and 24.9–120.8 ppm Mn (avg. 65.6). The green forage contained 0.58–3.21% Ca (avg. 1.76), 0.24–0.53% P (avg. 0.29), 1.49–2.94% K (avg. 2.10%), 0.36–0.57% Mg (avg. 0.45), 0.016–0.032% Fe (avg. 0.03), 7.3-10-3 ppm Cu (avg. 8.8 ppm), 121–464 ppm Mn (avg. 159 ppm). The leaf-protein concentrate (59% protein) contains 6.4% arginine, 2.5% histidine, 5.4% threonine, 1.7% tryptophan, 9.5% leucine, 5.3% isoleucine, 1.7% methionine, 6.87. lysine, 6.1% phenylalanine, and 6.8%. valine. Estrogenic disorders have been reported in cattle grazing largely on red clover, apparently due to activity of the isoflavones formononetin, biochanin A, and to some small extent daidzein and genistein. the flowers contain a number of phenolic compounds: daidzein, genistein, isotrifolin, isorhamnetin, pratol, pratensol, trifolin, and an antifungal compound trifolirhizin. They also contain coumaric acid, hentriacontane, heptacosane, myricyl alcohol, and b-sitosterol. On a dry basis flowers yield 0.028% of an oil containing furfural (Duke, 1981a).


Perennial, sometimes biennial, legume, sparingly pilose to glabrous, sometimes densely pilose [forma pilosum (Griseb.) Hayek]; stems erect or ascending, 1–5 cm long; leaves of basal rosette all long-petioled, those of stem moderately long-petioled to nearly sessile; leaflets oval or elliptic to cuneate-obovate, 1–3 cm long, 0.5–1.5 cm broad, subentire; stipules oblong-oval to oval-triangular, the free part broadly triangular, abruptly tapering to an erect setaceous tip; peduncles short or absent; heads mostly terminal, sessile, short-peduncled, usually closely subtended by the stipules of the upper pair of leaves, dense, subglobose to ovoid, 1.2–3 cm long; flowers sessile, 10–15 mm long, rosy purple to creamy-white (forma leucochraceum Aschers. & Prantl), erect; calyx-tube campanulate, narrower at base, 10-nerved, pubescent including the inner margin of the throat,.the teeth filiform from a triangular base, sparsely hirsute, porrect, the upper about equaling the tube, the lower almost twice as long; corolla about twice the length of the calyx; pods oblong-ovoid, circumscissile; seeds ovoid, asymmetrical, yellowish to purplish. Seeds ca. 600,000/kg; wt. kg/hl = 77 (Duke, 1981a).


Red clover cvs are of two types—early-flowering cvs that produce at least two cuttings per season, and late-flowering cvs that produce one cutting per season. Early-flowering cvs, also called medium or double-cut, are the most common type grown in the United States. Late-flowering cvs, called mammoth or single-cut, are grown where the growing season is short, as in high elevations or latitudes. Several cvs of both types are available. Taylor and Smith (1981 discuss a few of the more promising cvs. The cvs are rather limited in their areas of adaptation. Assigned to the Eurosiberian Center of Diversity, red clover, or cvs thereof is reported to exhibit tolerance to aluminum, disease, frost, fungus, grazing, hydrogen floride, high pH, low pH, mines, mildew, myco-bacteria, slope, virus, waterlogging, and weeds. (2n = 14, 28.)


Native to north Atlantic and central Europe, the Mediterranean region, Balkans, Asia Minor, Iran, India, Himalayas, Russia from Arctic south to east Siberia, Caucasus, and the Far East. It spread to England ca 1650 and was carried to America by British colonists (Taylor and Smith, 1981). Widely introduced and cultivated.


Native on wet to dry meadows, open forests, forest margins, field borders, and paths. Grows best on well-drained loam soil, but also adapted to wetter soils. Most soils that produce good crops of corn, tobacco or small grains will also produce a good crop of red clover. Loams, silt loams, and even fairly heavy soils are better than light sandy or gravelly soils. Some of these soils may need lime or fertilizer, or both. Red clover is most productive on soil that is within a pH range of 6.6 to 7.6. It also needs P and K to produce good yields; amounts needed can be determined by soil tests. Ranging from Boreal Moist to Wet through Subtropical Moist Forest Life Zones, red clover is reported to tolerate annual precipitation of 3.1 to 19.2 dm (mean of 91 cases = 8.6 dm), annual mean temperature of 4.9 to 20.3°C (mean of 91 cases = 10.6°C), and pH of 4.5 to 8.2 (mean of 84 cases = 6.3). Maximum yields obtained at pH >6 with adequate calcium. A photoperiod of at least 14 hours seems necessary for the double-cut type to flower, 16–18 hours for 'Mammoth' (Taylor and Smith, 1981; Duke, 1978).


In northeastern United States and Canada, and at higher elevation in southeastern and western United States, red clover grows as a biennial or short-lived perennial; at lower elevations in southeastern United States, it grows as a winter annual, and at lower elevation in western United States and Canada, it grows under irrigation as a biennial. Most red clover is spring seeded in a crop of fall- or spring-sown small grain. In the early spring the soil alternately freezes and thaws, thus covering the seed with soil. The small grain holds weeds in check while the clover is getting started. At lower elevations in southeastern and western United States, red clover is sown ca Oct. 15, no later than Dec. 15. In these areas it is most frequently sown without a companion crop. In south-eastern United States, late-summer seedlings can be successful on a seedbed, fallowed to prevent weed growth. Grass is extensively seeded with red clover. Clover-grass mixtures are usually superior to clover. In vitro and vivo experiments show that some lines of red clover perform better with ryegrass (Lolium multiflorum). Clover-grass yields better hay that cures more rapidly than pure clover hay. Animals are more likely to bloat on pure clover than on clover-grass pasture. Timothy has a high yield, and is ready to cut for hay with the red clover. Sow the grass in the early fall in the small-grain crop; sow the red clover in the small grain-grass in the spring. When the grain is harvested, remove the straw and stubble, as they tend to smother the clover and favor disease. Clover-hay yields from fields where the straw and stubble have been left are only about one-half as large as the yields from fields where they have been removed immediately after combining. Small-grain companion crops compete with red clover for mineral nutrients, moisture, and light. This competition can be reduced by grazing or clipping the small grain in late winter or early spring, just before stems begin growth., Grazing or clipping after clover stems have begun to branch will reduce small-grain yield.


The first year, graze or mow the clover 4 to 6 weeks before the first frost in the fall. If the stand is mowed, remove the clippings unless the total amount is quite small. The first crop of red clover, harvested early the second year is almost always harvested for hay or silage. In early bloom, red clover is leafy and produces its largest yield of protein per hectare. Cut red clover about 15 days after the first blooms appear. Cut stands grown with grass when clover is ready, not when grass is ready. Usually the second crop of red clover is pastured, harvested for seed, or grown for soil improvement and green manure. To harvest for hay, cut in early bloom; however, hay from this crop is occasionally unpalatable to cattle and sheep. A medium stand of red clover will produce two or three crops of hay the harvest year. Mammoth clover will produce one crop. After the crop is cut, allow it to wilt in swath and then rake it into small, loose windrows. It will cure about as rapidly in the windrows as in the swath, and fewer leaves will be lost in baling. Better, it can also be forced-air dried, which preserves the green color, lessens leaf shattering, and practically eliminates spoilage. Red clover and red clover-grass mixtures are frequently ensilaged. These crops make good ensilage if they are wilted slightly before ensiled, or if carbohydrate or chemical preservatives are added as they are ensiled. Red clover is one of the best legume pasture plants for livestock and poultry. Red clover and red clover-grass mixture pastures can be grazed or they can be cut green and fed to livestock and poultry. Red clover is also one of the better legumes for renovating old pastures. Clip or graze the old pasture closely. Chop up the sod with a disk or harrow before sowing the red clover seed. Red clover may be turned under as green manure to improve soil properties and increase yields of succeeding crops. Many crop rotations are possible for red clover, the oldest being a 3-year rotation of corn, oats or wheat and red dover. Other common rotations are: corn, soybeans, small grain, red clover; corn, small grain, red clover, rice, red clover; sugar beets, small grain, red clover; tobacco, rye or wheat, red clover-grass, grass, grass; potatoes, small grain, red clover. For seed production, the first crop of the second-year stand is usually harvested for hay or silage, the second crop may be harvested for seed. In most areas it is necessary to pollinate with bees, using 5 to 8 strong colonies of bees per hectare. Best seed yields occur when there is an abundance of bees, and soil fertility and moisture are adequate to promote good growth, and when the weather is warm and clear during the flowering period. Harvest the seed crop when the greatest number of seed heads are brown, usually 25–30 days after full bloom. Cut seed crop with mower. Let it cure in the swath or in small windrows. During rainy weather, the mowed crop cures better in swaths than in windrows. Windrowing is better during clear, warm weather because it reduces harvesting losses. Harvest the swathed or windrowed crops with a combine with a pickup attachment. Operate combine carefully to do a good harvesting job and to reduce harvesting losses. Artificial drying or drying by spreading seed thinly on a floor may improve the quality of the seed. Seed should be turned every few days until completely dry. Rough cleaning immediately after combining reduces the drying time and improves seed quality.

Yields and Economics

Under favorable conditions, seed yields average about 70–97 kg/ha, but under irrigation in western United States may reach 600–800 kg/ha. Polish seed yields range from 250–500 kg/ha (Wawryn, 1978). Several cvs of red clover, as 'Kenland', 'Pennscott', 'Dollard', and 'Chesapeake', where adapted, produce higher yields of forage and are more persistent than common red clover. Depending upon stage at which red clover is cut for forage, hay, or silage, yields vary from 900 to 19000 kg/ha. Red clover is the most Widely grown of the true clovers and forms one of the most important hay crops in temperate regions, especially when combined with grasses. In 1970, about 24,000 MT of red clover seed were produced on about 200,000 hectares, mainly in California, Iowa, Oregon, Kansas, and Virginia. Value of the seed crop is estimated around $23 million. In 1976, red clover hay averaged $66.44/MT. Assuming that 21.5 million MT of hay are produced annually, the economic value of the red clover hay alone is worth $1.4 billion per year or $265/ha. This ignores the significant value of pasture in red clover (Taylor and Smith, 1981).


Duke's phytomass files cite DM yields of 6–19 MT from such places as Romania, Switzerland, and the USSR. Finnish DM yields for 390 cvs ranged from 0.2–11.8 MT/ha (Ravantti, 1980). Belgians got 7 MT/ha from pure clover, nearly 13 MT intercropped with grasses (Andries, 1982). In Michigan, red clover cvs averaged 6.5–7.4 MT/ha compared with 10.3 for alfalfa and 6.2 for birdsfoot trefoil. Most of these figures are experiments. Taylor and Smith (1981) suggest that production yields, even in the US are lower: red clover with timothy yield about 21.5 million MT per year or closer to 4 MT/ha, pure red clover closer to 3 MT. It is estimated that red clover will provide 125–200 kg/ha N for use by subsequent crops. Taylor and Smith tabulate data suggesting that it takes ca 50,000 million Btu to produce 1 kg beef on feed lot pink clover, 45,000 million on haylage, and 40,000 million on grazing/feeding, the biggest, input, fertilizer being the biggest energetic input (ca 450 million Btu for lime, 540 for fertilizer), fuel (200 million for pasture, 420 for feedlot), and ca 130–230 million Btu for machinery, manufacture, transport, and repairs. Even residues are estimated at ca 4 MT/ha by Kvech (1979). Reducing Kvech's numbers by 10% to convert approximately to DM yields for residues, we have the following figures for Kourim, Czechoslovakia, rounded to the nearest MT: Medicago sativa, 7; Trifolium pratense, 4; Vicia faba, 4; Avena sativa, 3; Lolium perenne, 3; Secale cereale, 3; Trifolium repens, 3; Triticum aestivum, 3; Brassica rapa, 2; Hordeum vulgare, 2; Phacelia tanacetifolia, 2; Beta vulgaris, 1; Sinapis alba, 1; Solanum tuberosum, 1. Yields of other clover species reported in the Phytomass File are 2–11 for T. alexandrinum, 4–5 for T. hirtum, 7 for T. hybridum, 12–52 for T. incarnatum, 2–7 for T. repens, 9–11 for T. resupinatum, 8–13 for T. subterraneum, and 2 for T. vesiculosum. The USDA (1983) reported yields of 0.5–52 MT DM/ha/yr with N-fixation of 46–418 kg in T. incarnatum.

Biotic Factors

Duke (1981a) lists many fungi, insects and nematodes plaguing red clover. Red clover is attacked by many fungi, some of which may cause serious losses. Among the fungi: Alternaria tenuis, Ampelomyces quisqualis, Ascochyta trifolii, Botrytis anthopila, B. cinerea, Brachysporum trifolii, Cerospora zebrina (summer black stem), Chaetomium cochliodes, Colletotrichum destructivum, C. trifolii (southern anthracnose), Corticium solani, Cylindrocladium scoparium, Cymadothea trifolii, Didymella trifolii, Didymium sturgisii, Erysiphe communis f. trifolii, E. martii, E. polygoni (powdery mildew), Fusarium acuminatum, F. avenaceum, F. equiseti, F. gramineaum, F. oxysporum (root rot), F. pose, F. roseum, F. solani, Kabatiella caulivora (northern anthracnose), Leptosphaerulina americana, L. briosiana, L. trifolii, Metasphaeria boucera, Microsphaeria alni, Mycosphaerella carinthiaca, Oidium erysiphoides, Ophiobolus collapsus, O. graminis, Peronospora pratensis, P. trifoliorum, Phoma trifolii (spring black stem), Phyllachora trifolii, Phymatotrichum omnivorum, Phytophthora cactorum, Phyllosticta trifolii, Plenodomus melioti, Pleospora herbarum, Polythrincium trifolii, Pseudopeziza trifolii, Pseudoplea medicaginis, P. trifolii (pepper spot), Pyrenopeziza jonesii, Pythium debaryanum, Rhizoctonia crocorum, Rh. leguminicola (black patch), Rh. solani, Rh. violacea, Sclerotinia kitajimana, S. sclerotiorum, S. spermophila, S. trifoliorum (crown rot), Septoria compta, Sporonema phacidioides, S. trifolii, Sphaerulina trifolii, Stagonospora compta, S. meliloti, S. recedens, Stemphylium sarcinaeforme (target spot), S. botryosum, Sclerotium delphinii, S. rolfsii, S. bataticola, Stictus pustulata, Thielaviopsis basicola, Thyrospora sarcinaeformis, Uromyces fallens, U. minor, U. nerviphilus, U. trifolii, U. trifolii-repentis, Vermicularis dematium, Verticillium dichotomum, and Volutella fusarioides. Red clover's life cycle may be shortened by buildups of Fusarium, Gliocladium, and Rhizoctonia in the soil. Since it is impractical to control diseases with fungicides, stress is placed on finding or developing disease resistant cvs. Bacteria causing diseases in red clover include: Bacillus lathryi (red clover streak), Pseudomonas radiciperda, and Ps. syringae. Parasitic on red clover are Cuscuta epithymum and C. pentagona. Viruses causing diseases in red clover include the following: bean yellow mosaic (BYMV), red clover vein mosaic (Marmor trifolii), clover mosaic, Pisum virus 2, lucerne mosaic, Trifolium virus 1, common pea mosaic, clover phyllody virus, rugose leaf curl, tobacco mosaic, white clover mosaic, and potato calico (Marmor medicaginis var. solani). The most promising method for control of many red clover diseases is development of resistant cvs. Some progress has been made in developing cvs resistant to northern and southern anthracnose and powdery mildew. For control methods, local agents should be consulted. Nematodes isolated from red clover include: Acrobeles ciliatus, Acrobeloides emarginatus, Aphelenchoides ritzemabosi, Aphelenchus avenae, Boleodorus thylactus, Cephalobus spp., Chiloplacus spp., Criconemella curvata, C. lobata, C. rustica, Ditylenchus destructor, D. dipsaci, Eucephalobus spp., Helicotylenchus cairnsi, H. canadensis, H. digonicus, H. dihystera, H. multicinctus, H. pseudorobustus, Heterodera davertii, H. glycines, H. goettingiana, H. lespedezae, H. trifolii, Hoplolaimus galeatus, H. tylenchiformis, Longidorus elongatus, L. maximus, Meloidogyne arenaria, M. artiellia, M. hapla, M. incognita, M. i. acrita, M. javanica, Merlinius brevidens, M. macrurus, Neotylenchus spp., Paratylenchus aciculus, P. brevihastus, P. hamatus, P. projectus, P. sarissus, P. tenuicaudatus, Pratylenchus brachyurus, P. coffeae, P. neglectus, P. penetrans, P. pratensis, P. scribneri, P. tumidiceps, Psilenchus hilarulus, Pungentus pungens, Rotylenchulus reniformis, Rotylenchus goodeyi, R. robustus, Scutellonema brachyurum, Trichodorus christiei, Tylencholaimus mirabilis, Tylenchorhynchus agri, T. annulatus, T. claytoni, T. dubius, T. maximus, T. parvus, Tylenchus costatus, T. davainii, and Xiphinema americanum. Amosu and Taylor (1975) showed that Tylenchorhynchus agri, which feeds only on the epidermal cells in the region of root elongation, actually stimulates the growth. The most destructive insects reported on red clover include the following: clover root borer (Hylastinus obscurus), clover root curculio (Sitona hispidulus), clover seed chalcid (Bruchophagus gibbus), lesser clover leaf weevil (Hypera nigrirostris), potato leafhopper (Empoasca fabae), yellow clover aphid (Therioaphis trifolii), meadow spittlebug (Philaenus spumarius), clover seed midge (Dasineura leguminicola) clover leafhopper (Aceratagallia sanguinolenta), and pea aphid (Acyrthosiphon pisum). "No practical controls of these insects are available." (Taylor and Smith, 1981). Red clover is pollinated by honeybees and bumblebees.


Complete list of references for Duke, Handbook of Energy Crops
Last update Friday, January 9, 1998 by aw