Birdsfoot trefoil (Lotus corniculatus) and narrowleaf trefoil (Lotus tenuis).

The scientific name of birdsfoot trefoil is Lotus corniculatus L. (Duke, 1981; Miller,1984b; Grant and Marten, 1985). The scientific name of narrowleaf trefoil is Lotus tenuis.

Birdsfoot trefoil has at least 25 varieties, including 'Carroll,' 'Empire,' 'Leo,' 'Norcen,' and 'Viking' for use in Canada, and 'Fergus' for use in the South (e.g., northern Alabama). 'Vega II' was developed for increased seedling vigor, winter growth, and yield in California (Grant and Marten, 1985).

Narrowleaf trefoil (Lotus tenuis) has linear-lanceolate leaflets and small flowers that start yellow and turn orange-red with age. The root system is very shallow. There is cross-compatibility with L. corniculatus suggesting that Lotus tenuis may be a progenitor species. The latter form is abundant in California (Grant and Marten, 1985), and there is a cultivar called 'Los Banos' that has been grown widely within California (Duke, 1981).

Based on the account by Grant and Marten (1985), birdsfoot trefoil seed are small, 825,000-925,000 seed/kg, and range in color from olive green to brown, to almost black. Seedcoats may be mottled. A high proportion of birdsfoot trefoil seed is hard and, therefore, impermeable to water. The proportion can be reduced from 0.90 to 0.40 by combine harvesting. Scarification may be needed to ensure prompt stand development.

Seeds require scarification to ensure imbibition of water and germination. A firm seedbed is required; seedlings are not vigorous and compete poorly with nurse crops, weeds, and grasses (Duke, 1981).

Grant and Marten (1985) stated that narrowleaf trefoil (Lotus tenuis) has linear-lanceolate leaflets and small flowers that start yellow and turn orange-red with age. The root system is very shallow. There is cross-compatibility with L. corniculatus suggesting that Lotus tenuis may be a progenitor species. This form is abundant in California. Birdsfoot trefoil plants at maturity have many highly-branched stems growing from a single crown. Roots can produce new shoots.

Miller (1984b) mentioned that birdsfoot trefoil leaves are compound, with 5 leaflets; that 5-6 pods develop per peduncle, each pod containing 10-15 seeds; and that seed pods turn light brown or black when mature.

Birdsfoot trefoil tolerates mean annual temperatures of 5.7-23.7 with the mean of 59 cases being 11.1 C, and tolerates frost (Duke, 1981). Narrowleaf trefoil tolerates a mean annual temperature of 7.0-16.9 C, with a mean of 10 cases of 10.2 C.

Revegetation seed purchases for Sierra and Rocky Mountain arboreal regions, mining revegetation, and ski slope sites include birdsfoot trefoil. Data is presented at revegetation meetings showing the range for birdsfoot trefoil to be from 12,000 ft. elevation to below sea level. The primary seed production region is in upper Minnesota and Canada, which also has temperature extremes (Fred Thomas, pers. comm.).

Birdsfoot trefoil is native throughout almost all of Europe and parts of Asia, including Iran and India; it ranges from the Boreal Moist to Wet through Subtropical Moist Forest Life Zone; and it has been introduced to many areas, including Australia, North America, and South America (Duke, 1981). In California, it occurs occasionally in lawns and along roadsides (Munz, 1973). It is widely distributed, and most diverse in the Mediterranean region; it does not do well in the southeastern U.S., where it is prone to root diseases (Grant and Marten, 1985). Narrowleaf trefoil is native throughout most of Europe, except northeast and extreme south, and range extends through Crimea, Caucasus, and Central Asia; range comprises Cool Temperate Steppe to Wet through Warm Temperate Moist Forest Life Zone (Duke, 1981).

Both birdsfoot trefoil and narrowleaf trefoil are grown on marshy, alkaline, estuary, delta sites in California. These are often submerged for up to two months time during the winter Mediterranean climate. Personal communication with Bob Willoughby, UCCE Farm Advisor for pastures, listed the tolerances as up to 6 weeks submergence for birdsfoot trefoil and more than 8 weeks for narrowleaf trefoil.

Birdsfoot trefoil benefits from addition of P (Grant and Marten, 1985) and sometimes K (Duke, 1981).

Birdsfoot trefoil tolerates soil pH of 4.5-8.2 (mean of 56 cases 6.4); the corresponding figures for narrowleaf trefoil are 5.6-8.0 (mean of 9 cases, 6.7); it is reported as doing well from pH 4.5-7.9, with best nodulation at pH 6.0-6.5 (Duke, 1981). Birdsfoot trefoil produces best on soil pH 6.2-6.5 or higher, and tolerates acid soils better than does alfalfa (Grant and Marten, 1985).

Birdsfoot trefoil will grow on poorly-drained, droughty, infertile, acid, or moderately alkaline soils, and is mildly salt tolerant (Duke, 1981). It tolerates waterlogged soils (Grant and Marten, 1985). Narrowleaf trefoil is native to wet meadows and sands, but tolerates dry soils that when flooded drain poorly; it does well on saline and alkaline soils (Duke, 1981).

No specific information was found in the literature, but Bugg (pers. comm.) observed birdsfoot trefoil as a perennial cover crop in organic vineyards and pear orchards in Mendocino County, California.

Birdsfoot trefoil is moderately tolerant of salt; narrowleaf trefoil grows well on saline and alkaline soils in California (Duke, 1981).

Broadleaf trefoil is the perennial legume that is planted in all 'alkaline' mixtures and pasture plantings throughout the intermountain region and the great basin region (Fred Thomas, pers. comm.)

To aid establishment of the seedlings of birdsfoot trefoil, weed control can entail pre-plant application of EPTC or postemergence 2,4DB or dalapon (in the absence of grasses) (Duke, 1981).

Birdsfoot trefoil is a long-lived, slightly-decumbent perennial legume that can develop new plants by producing roots at the internode or from axillary buds at the node (Miller, 1984b). Birdsfoot trefoil flowers are clustered, with 4-8 per peduncle (Miller, 1984b) and are bee pollinated (Grant and Marten, 1985). The species has a high level of self-incompatibility, and most seed result from outcrossing (Grant and Marten, 1985). Seeds ripen 25-30 days after pollination (Miller,1984b; Grant and Marten, 1985). Five to 6 pods develop per peduncle, each pod containing 10-15 seeds (Miller,1984b). Seed are scattered when the pods split and twist spirally (Grant and Marten, 1985). After each harvest, nodules on birdsfoot trefoil senesce, and new nodules form during regrowth (Grant and Marten, 1985).

Birdsfoot trefoil seeding rate is from 5-12 kg/ha. High rates of seeding are not essential to ensure long-term high yields (Grant and Marten, 1985).

For Birdsfoot trefoil, smooth seedbeds are required; seed is small and seedling growth slow, so seed should preferably be buried 0.6 cm and certainly no deeper than 1.3 cm (Grant and Marten, 1985). Birdsfoot trefoil % seedling emergence was 31, 18, 8, and 3 at respective seeding depths of 0.6, 1.3, 1.9, and 2.5 cm (0.2, 0.5, 0.7, and 1 inch) (Miller,1984b).

For Birdsfoot trefoil, smooth seedbeds are required; seed is small and seedling growth slow, so seed should preferably be buried 0.6 cm and certainly no deeper than 1.3 cm (Grant and Marten, 1985). This species can establish with spring or autumn seeding (Grant and Marten, 1985). Seeding rate is from 5-12 kg/ha. High rates of seeding are not essential to ensure long-term high yields (Grant and Marten, 1985). A high proportion of seed is hard and, therefore, impermeable to water. The proportion can be reduced from 0.90 to 0.40 by combine harvesting. Scarification may be needed to ensure prompt stand development (Grant and Marten, 1985). Cultipacking or rolling improves seed-to-soil contact and enhances establishment (Miller,1984b).

Birdsfoot trefoil can establish with spring or autumn seeding (Grant and Marten, 1985).

Birdsfoot and narrowleaf trefoils both require rhizobial inoculant type "K" (Nitragin) (Duke, 1981).

Birdsfoot trefoil is widely available from production areas in the upper Midwest and Canada. Some seed is also imported from South America. Narrowleaf trefoil has ceased to be available in the market place since 1985 when the Dixon and Suisun growers quit production. Two major California seed companies (Germains and Kamprath) have attempted production, including one field in Minnesota but have been unsuccessful in achieving production (Fred Thomas, pers. comm.)

Birdsfoot trefoil flowers from June through September (Munz, 1973) or when days are long, from 16 to 18 hours in length (Grant and Marten, 1985).

Seed ripen 25-30 days after pollination (Miller,1984b; Grant and Marten, 1985). Seed are scattered when the pods split and twist spirally (Grant and Marten, 1985).

Birdsfoot trefoil flowers are bee pollinated; there is a high level of self-incompatibility, and most seed result from outcrossing (Grant and Marten, 1985). 5-6 pods develop per peduncle, each pod containing 10-15 seeds (Miller, 1984b). Seed ripen 25-30 days after pollination, at which time, seed pods turn light brown or black (Miller, 1984b). Seed are scattered when the pods split and twist spirally (Grant and Marten, 1985). Seed harvest should occur when 70-80% of pods have matured (Duke, 1981). As indicated by Duke (1981), mow the crop, windrow to dry, and combine. Alternatively, the mowed crop could be stored like hay and later threshed, but this usually results in unacceptable loss of seed (Duke, 1981).

Birdsfoot trefoil seed can be stored for 20 years (Grant and Marten, 1985).

Birdsfoot trefoil is a long-lived, slightly-decumbent perennial legume that can attain a height of 60-90 cm (Miller, 1984b). At maturity, plants have many highly-branched stems growing from a single crown; roots can produce new shoots (Grant and Marten, 1985). Decumbent and intermediately-statured cultivars of birdsfoot trefoil show the best persistence in heavily-grazed pastures because regrowth is more rapid (Grant and Marten, 1985).

New cultivars were released in 1997 for sale in 1999 that creep by underground stolons (Fred Thomas, pers. comm.)

Birdsfoot trefoil can attain a height of 60-90 cm (Miller, 1984b). Mean height (+/- S.E.M.) of fall-seeded broadleaf birdsfoot trefoil was 19.1 +/- 2.4 in the following May (Mendocino County, California) (Bugg et al., 1996).

The birdsfoot trefoil root system is not as deep as that of alfalfa and is more highly branched in the shallower (30-60 cm depth) soil strata (Grant and Marten, 1985). Plants at maturity have many highly-branched stems growing from a single crown. Roots can produce new shoots (Grant and Marten, 1985). Kutschera (1960) reported that birdsfoot trefoil generally roots to a depth of 30-120 cm.

Birdsfoot trefoil % seedling emergence was 31, 18, 8, and 3 at respective seeding depths of 0.6, 1.3, 1.9, and 2.5 cm (0.2, 0.5, 0.7, and 1 inch) (Miller, 1984b).

Based on the account by Miller (1984b), birdsfoot trefoil reseeds itself by pod shattering. It should be cut to a height of about 5-10 cm (2-4 inches); closer mowing would remove too many of the axillary buds needed for regrowth (Miller, 1984b).

Birdsfoot trefoil should be cut to a height of about 5-10 cm (2-4 inches); closer mowing would remove too many of the axillary buds needed for regrowth (Miller, 1984b). Decumbent and intermediately-statured cultivars of birdsfoot trefoil show the best persistence in heavily-grazed pastures because regrowth is more rapid (Grant and Marten, 1985). Companion (nurse) crops of grasses can aid weed control and help reduce erosion during establishment of birdsfoot trefoil. The early mowing of these grasses can be helpful in reducing competition (Grant and Marten, 1985).

Birdsfoot and narrowleaf trefoils are perennials and are typically managed no-till.

A high proportion of birdsfoot trefoil seed is hard, that is, impermeable to water. The proportion can be reduced from 0.90 to 0.40 by combine harvesting. Scarification may be needed to ensure prompt stand development (Grant and Marten, 1985). Seed harvest should occur when 70-80% of pods have matured. As indicated by Duke (1981), mow the crop, windrow to dry, and combine. Alternatively, the mowed crop could be stored like hay and later threshed, but this usually results in unacceptable loss of seed (Duke, 1981).

In California, seed production narrowleaf trefoil was produced in the Dixon and Suisun area but shattering was a problem to the extent that production was poor. With the removal of chemicals in combination with grazing, most producers quit production in the mid-1980s (Fred Thomas, pers. comm.).

Mowers of various types may be used with birdsfoot and narrowleaf trefoils (Bugg, pers. comm.).

The following was taken from Duke (1981). Birdsfoot trefoil is used as an excellent non-bloating forage, and is good as pasture, hay, or silage for horses and cattle. It is especially good on infertile, poorly-drained soils, and those that are difficult to cultivate. It is a drought resistant ground cover. Duke (1981) mentioned that narrowleaf trefoil is suitable for pasture or hay production on dry but poorly-drained soils.

Birdsfoot trefoil is included in all 'beneficial insectary' mixes mareketed in California. Germain Seeds even calls their mixture Trefoil Insectary Mix. As noted in other sections, birdsfoot trefoil is a rich insectary and long-lived plant that is used as a base for much of the California areas including the alkaline soils of the San Joaquin Valley of California (Fred Thomas, pers. comm.)

Grasses are good complements to birdsfoot trefoil because they limit lodging by the legume and invasion by weeds (Grant and Marten, 1985). Companion (nurse) crops of grasses can aid weed control and help reduce erosion during establishment of birdsfoot trefoil. The early mowing of these grasses can be helpful to reduce competition (Grant and Marten, 1985). If a companion grass is seeded along with birdsfoot trefoil, it should be a slow-growing grass, rather than a highly-competitive species like oat or ryegrass (Miller, 1984b).

In Uruguay, Danso et al. (1991a) studied a triculture of birdsfoot trefoil, white clover and Festuca arandinacea. Approximately 130 kg N/ha was derived from fixation during the first year of the study. Only in the first harvest did white clover exceed birdsfoot trefoil in herbage or total N content. Birdsfoot trefoil derived 91% of its N from the atmosphere, as compared with 88% for white clover. White clover was subject to a depression of N fixation when N-fertilizer application was increased from 2 to 10 kg N/ha, but birdsfoot trefoil showed no such depression. In the first year of the study, the two legumes contributed almost equally to the total 130 kg N/ha fixed, but in the last two harvests of the second year, birdsfoot trefoil contributed 95% of the 46 kg N/ha fixed.

Farnham and George (1994) in Ames, Iowa, found that birdsfoot trefoil grown in biculture with orchardgrass (Dactylis glomerata) fixed from 90-138 kg/ha-yr. Fixed N transferred to orchardgrass ranged from 4-42 kg/ha-yr. in the 2-year study, and from 39-46 kg/ha-yr. in the 2nd year.

White and Scott (1991) in New York found that yield of cereal rye was less affected by living mulch of white clover, 'Ladino' clover, or red clover than of crown vetch, birdsfoot trefoil or alfalfa.

In New York, White and Scott (1991) seeded wheat and cereal rye into established living mulches. Weed biomass varied among living mulches, with highest values observed for control (1,043 kg/ha), and crownvetch (703 kg/ha) and lowest for alfalfa (51kg/ha). Birdsfoot trefoil (300 kg/ha), ladino clover (412 kg/ha), and white clover (503 kg/ha) had intermediate values.

In Salinas, living mulches of white clover, strawberry clover, or birdsfoot trefoil/red clover led to similar yields and per head weights of broccoli when compared to control plots (Costello, 1994). Rates of infestation of broccoli by cabbage aphid (Brevicoryne brassicae) were significantly lower with living mulches.

Dry above-ground biomass of broadleaf birdsfoot trefoil was: 6.443+/-3.989 Mg/ha, Mean +/- S.E.M. in mid-May, 1991 for cover crops seeded during October, 1990, at Blue Heron Vineyard, Fetzer Vineyards, Hopland, Mendocino County, California; biomass of the cover crop plus resident vegetation was 8.815+/-3.409 Mg/ha (Bugg et al., unpublished data).

Duke (1981) wrote that birdsfoot trefoil hay contains 13.4-28.8% crude protein, and the green forage 14.8-29.1%. Based on the assumption that 6.25% of protein is N, these figures translate to 0.8775-1.7625% and 0.925-1.81875% of the dry biomass being N. No yield data were presented by Duke (1981). Miller (1984b) wrote that annual hay production ranged from 4-10 Mg/ha. These figures combined with the above-listed values for green forage suggest annual production of 37-181.88 kg N/ha. Gershuny and Smillie (1986) wrote that birdsfoot trefoil ploughed under yields over 100 lb N/a.

In a field study in Uruguay, Mallarino and Wedin (1990) found that N-fixation was more markedly depressed through the application of nitrogen fertilizer (100kg/ha) for birdsfoot trefoil than for white clover or red clover.

In combination with tall fescue (Festuca arundinacea), year diculture stands with birdsfoot trefoil, white clover, and red clover led to respective annual total N fixation of 70-223, 42-200, and 49-277 kg N/ha. White clover-tall fescue mixes did not require legume domination in order to maximize total N fixation. Red clover gave the greatest N fixation among the legumes tested (Mallarino et al., 1990).

Duke (1981) wrote that the hay of birdsfoot trefoil contained on a moisture-free basis 0.16-0.49% P, 1.47-1.97 % K, 0.31-0.78% Mg, 0.013-0.015% Fe, 0.6% Mn, and 1.04-1.92% Ca.

There is no specific information on the effects on soil of birdsfoot trefoil. The taproot is not so deep as those of alfalfa or sweetclover (Miller, 1984b), so birdsfoot trefoil is unlikely to affect soil at depth as those species can (Bugg, pers. comm.).

Birdsfoot trefoil is as nutritious to cattle as alfalfa or more so (Grant and Marten, 1985), and it does not cause bloating. (Miller,1984b). Decumbent and intermediately-statured cultivars of birdsfoot trefoil show the best persistence in heavily-grazed pastures because regrowth is more rapid (Grant and Marten, 1985).

There is no specific information on effects by birdsfoot trefoil on workers. The low stature of the plant should enable easy access to orchard or vineyard workers (Bugg, pers. comm.).

Minute pirate bug (Orius tristicolor), a generalist predator of various agricultural pests, may be abundant in the inflorescences of birdsfoot trefoil (Bugg, pers. comm.). Duke (1981) listed the following phytophagous arthropods as being associated with birdsfoot and narrowleaf trefoils: meadow spittlebug (Philaenus spumarius), alfalfa plant bug (Adelphocoris lineolatus), potato leafhopper (Empoasca fabae), clover seed chalcid (Bruchophagus platypterus), and white grub (Phyllophaga hirticula). The latter damages the roots. Duke (1981) mentioned that trefoils are mostly self-incompatible and require insects (mainly Hymenoptera) for pollination.

Birdsfoot trefoil is included in all 'beneficial insectary' mixes marketed in California. Germain Seeds even calls their mixture Trefoil Insectary Mix. As noted in other sections, birdsfoot trefoil is a rich insectary and long-lived plant that is used as a base for much of the California areas including the alkaline soils of the San Joaquin Valley of California (Fred Thomas, pers. comm.)

Nematodes associated with birdsfoot trefoil include Helicotylenchus sp., Heterodera glycines, H. trifolii, Meloidogyne arenaria, M. hapla, M. incognita, M. incognita acrita, M. javanica, Paratylenchus penetrans, P. pratensis, P. vulvus, T. christiei, and Tylenchorhynchus sp. (Duke, 1981).

Birdsfoot trefoil does not do well in the Southeast, where it is prone to root diseases (Grant and Marten, 1985).

Grasses are good complements to birdsfoot trefoil because they limit lodging by the legume and invasion by weeds (Grant and Marten, 1985). Companion (nurse) crops of grasses seeded with the legume can aid weed control and help reduce erosion during the establishment phase. The early mowing of these grasses can be helpful in reducing excessive competition (Grant and Marten, 1985). In plots seeded to birdsfoot trefoil in late October, 1990, weed above-ground biomass data (dry) was 2.4+/-0.9 Mg/ha, Mean +/- S.E.M. (about 48% of the weed biomass occurring in control plots) during mid-May, 1991 Blue Heron Vineyard (Fetzer Vineyards), Hopland, Mendocino County, California. Dominant winter annual weeds were chickweed, shepherds purse, rattail fescue, and annual ryegrass. In early May, vegetational cover by birdsfoot trefoil was 32.5+/-6.0 % (Mean +/- S.E.M.) (Bugg et al., 1996).