Securigera varia (L.) Lassen

Synonyms: Coronilla varia L.

Author: John Frame

COMMON NAME: Crownvetch

DESCRIPTION
Perennial, decumbent to ascending, with angular hollow stems, height 1–1.5 m. Leaves imparipinnate with 11–21 pairs of sessile leaflets, plus the terminal leaflet. Deeply tap-rooted with numerous lateral roots, spreading via rhizomes. Numerous inflorescences arising from leaf axils are umbels, variegated in colour from white and purple. Seed pods indehiscent with 3–7 cylindrical segments each containing one yellow-orange to reddish-brown rod-shaped seed. High proportion of hard seeds. Number of seeds kg^-1: 240 000–245 000. Average 1000-seed weight: 4.1g.

DISTRIBUTION
Indigenous to central Europe. Introduced to other parts of Europe, Asia Minor, North America and South Africa.

CHARACTERISTICS
Adapted to well drained, fertile soils, pH 6 and above, though established swards are tolerant of moderately fertile, acid soils (Miller and Hoveland, 1995). It has slow germination, seedling emergence and sward development compared with red clover, birdsfoot trefoil or alfalfa (Peiffer, McKee and Risius, 1972). It is drought resistant, winter hardy, moderately shade tolerant (Langille and McKee, 1962) and suited to infrequent defoliation, with a slow regrowth rate. Delaying the first cut to full bloom growth stage maximizes the proportion of axillary buds producing regrowth (Brann and Jung, 1974). Carbohydrate reserves stored in the roots are depleted initially with the start of spring growth and with regrowths after defoliation, but increase again as plant growth matures, the cyclic pattern being similar to that for alfalfa (Reynolds and Smith, 1962; Langille and McKee, 1968). The growing season is relatively short in cool climates.
Ability to spread naturally It spreads by rhizomatous growth.
Compatibility in mixture It is compatible with non-aggressive companion grasses such as smooth-stalked meadow grass (Poa pratensis), cocksfoot (Dactylis glomerata) and timothy (Phleum pratense).
Nitrogen fixation Seed inoculation with an effective and competitive strain of Rhizobium is necessary when seeding land without a previous history of growing crownvetch. Reputed to have good N2 -fixation ability.

BREEDING
Cross-pollinated by bumble bees (Bombus spp.) and honey bees (Apis mellifera). Existing cultivars were developed by natural selection from ecotypes.
Cultivars Three cultivars, Emerald, Penngift and Chemung, have been developed in the United States of America.
Seed production Seed crops are usually cut, windrowed and combine harvested. Seed yields are low not only because crownvetch has indeterminate flowering, but also because the seed pod segments shatter easily when dry and lose their seed (Al-Tikrity et al., 1974). Typically, commercial seed yields are circa 100 kg ha^-1 (Miller and Hoveland, 1995).

AGRONOMY
Establishment A well cultivated, uniform and firm seed bed is required for good results. Seeds require scarification, and are best drilled without a cover crop at 10–15 mm and the seed bed consolidated. Seeds need scarification before sowing, and are sown at 6–11 kg ha^-1. Seed germination is best at temperatures of 15–25°C (Townsend and McGinnies, 1972a), and has a slow establishment phase. It has been direct drilled (sod seeded) successfully into swards of smooth-stalked meadow grass (Miller and Hoveland, 1995) and switchgrass (Panicum virgatum) (Blanchet et al., 1995). Used in the United States of America for erosion control and reclamation of land disturbed by mining and other activities (Sharp, Schertz and Carlsson, 1995).
Nutrient requirements Adequate soil fertility is required to ensure satisfactory yields.
Weeds Its ability to compete with weeds is poor in the early establishment phase because of lack of seedling vigour, and therefore problem weeds should be culturally, mechanically or chemically controlled before sowing the crownvetch. Established swards with a dense cover are competitive towards weed ingress.
Pests Information is sparse concerning pest attack, but it appears to be relatively free of pests (Miller and Hoveland, 1995).
Diseases Information is sparse on susceptibility or tolerance to specific diseases, though damping-off, root rot and wilt, all caused by Pythium myriatybum has been reported (Dutky and Lumsden, 1986). However, in general, it appears to be relatively free of diseases (Miller and Hoveland, 1995).
Forage production In general, higher yields of DM have been obtained from infrequent (2–3 cuts) than from a more frequent cutting regime (Mays and Evans, 1972; Hart, Thompson and Hungerford, 1977). Dry matter yields of 10.0, 8.0 and 4.9 t ha^-1 were harvested from 2, 3 and 5 cuts, respectively, by Burns, Cope and Barrick (1977). Highest yields (10–11 t ha^-1) were obtained at the full flowering stage of growth, though the decumbent growth habit of plants made efficient harvesting at this stage difficult (Brann and Jung, 1974). At one dryland site in South Africa, crownvetch and alfalfa had similar DM yields (?6.0 t ha^-1) but at another, wetter, site, crownvetch yielded 10.6 t ha^-1 compared with 7.1 t ha^-1 from alfalfa (LeRoux, Howe and du Toit, 1988).

NUTRITIVE VALUE
It has good nutritive value, rich in protein and minerals, with digestibility highest at early growth stages when the proportions of leaf to stem are highest. Data from trials in Quebec, Canada, are shown in Tables 1 and 2
It is acceptable forage to grazing stock, but they need to become accustomed to it (Bryant et al., 1977).
Anti-quality factors Aliphatic nitro compounds (glucose esters of beta-nitropropanoic acid), that are toxic to non-ruminants but not to ruminants, are present in fresh forage, but not in silage or hay (Gustine, 1979).

Table 1. Nutritive value of crownvetch (g kg^-1 DM) at three stages of primary growth (Means of 3 cultivars over 3 years).

Key: CP = crude protein; NDF= neutral detergent fibre; ADF = acid detergent fibre.
Source: Based on Gervais, 2000.

Table 2. Mineral composition of crownvetch at three stages of primary growth (Means of 3 cultivars over 3 years).

KEY: CP = crude protein; NDF= neutral detergent fibre; ADF = acid detergent fibre.
SOURCE: Based on Gervais, 2000.

UTILIZATION
Grazing management It is suited to rotational grazing systems rather than continuous stocking, which adversely affects plant persistence (Burns, Cope and Barrick, 1977). Herbage productivity was similar under several different grazing systems but weeds increased noticeably in the third grazing season, particularly with continuous and near-continuous grazing (Barnes and Dempsey, 1992).
Conservation management Suited to conservation as hay or silage, but care in handling during haymaking is required to avoid loss of the nutritious leaf fraction.

ANIMAL PERFORMANCE
In general, satisfactory performance has been obtained from stock grazing crownvetch, for example, from suckler cows, calves and steers (Burns et al., 1969; Burns, Cope and Barrick, 1977; Bryant et al., 1977). Six-month-old sheep fed cut crownvetch and alfalfa at similar growth stages had average daily liveweight gains of 91 and 122 g, respectively (Reynolds, Jackson and Henson, 1969), the superiority of alfalfa being attributable to a higher forage digestibility. In a comparison of leafy crownvetch hay with an in vitro DDM of 687 g kg^-1 versus third-cut alfalfa hay (in vitro DDM of 529 g kg^-1) fed to dairy heifers, average daily liveweight gains were 0.98 and 0.65 kg, respectively (Burns, Mochrie and Cope, 1972). In South Africa, the grazing capacity for a 5-month grazing season was estimated at 30–35 weaner lambs ha^-1, with individual liveweight gains of the order of 20 kg over a grazing period (Barnes and Dempsey, 1992).

MAIN ATTRIBUTES
It provides high forage yields of good nutritive value and is persistent, with the ability to spread by rhizomes and create a dense sward. It is relatively free of pests and diseases, non-bloat-inducing, and an excellent stabilizing plant for disturbed sites.

MAIN SHORTCOMINGS
Its slow establishment phase renders it prone to weed invasion. The growing season is relatively short in cool latitudes. There is low initial acceptability by stock.

MAIN REFERENCES
AL-TIKRITY, W.M., McKEE, G.W., CLARKE, W.W., PEIFFER, R.A. and RISIUS, M.L. (1974) Seed yield of Coronilla varia L. Agronomy Journal, 66, 467-468.
BARNES, D.L. and DEMPSEY, C.P. (1992) Towards optimum grazing management for sheep production on crownvetch (Coronilla varia L.). Journal of the Grassland Society of South Africa, 9, 83-89.
BLANCHET, K.M., GEORGE, J.R., GETTLE, R.M., BUXTON, D.R. and MOORE, K.J. (1995) Establishment and persistence of legumes interseeded into switchgrass. Agronomy Journal, 87, 935-941.
BRANN, D.E. and JUNG, G.H. (1974) Influence of cutting management and environmental variation on the yield, bud activity, and autumn carbohydrate reserve levels of crownvetch. Agronomy Journal, 66, 767-773.
BRYANT, H.T., HAMMES, R.C., BLASER, R.E. and FONTENOT, J.P. (1977) Evaluation of acceptability by beef cattle of crownvetch grazed at several stages of maturity. Journal of Animal Science, 45, 939-944.
BURNS, J.C., COPE, W.A. and BARRICK, E.R. (1977) Cow and calf performance, per hectare productivity, and persistence of crownvetch under grazing. Agronomy Journal, 69, 77-81.
BURNS, J.C., MOCHRIE, R.D. and COPE, W.A. (1972) Responses of dairy heifers to crownvetch, sericea lespedeza and alfalfa forages. Agronomy Journal, 64, 193-195.
BURNS, J.C., COPE, W.A., GOODE, L., HARVEY, R.W. and GROSS, H.D. (1969) Evaluation of crownvetch (Coronilla varia L.) by performance of beef cattle. Agronomy Journal, 61, 480-481.
Dutky, E.M. & Lumsden, R.D. 1986. Damping-off, root rot and wilt of crownvetch (Coronilla varia) caused by Pythium myriotybum. Canadian Journal of Plant Pathology, 8: 107–108. GERVAIS, P. (2000) L’astragale pois chiche, la coronille bigarrée et le sainfoin (cicer milkvetch, crown vetch and sainfoin). Université Laval, Québec, 190pp
GUSTINE, D.L. (1979) Aliphatic nitro compounds in crownvetch: A review. Crop Science, 19, 197-203.
HART, R.H., THOMPSON III, A.J. and HUNGERFORD, W.E. (1977) Crownvetch-grass mixtures under frequent cutting : Yields and nitrogen equivalent values of crownvetch cultivars. Agronomy Journal, 69, 287-290.
LANGILLE, A.R. and McKEE, G.W. (1962) Early growth of crownvetch under reduced light. Agronomy Journal, 62, 552-554.
LANGILLE, A.R. and McKEE, G.W. (1968) Seasonal variation in carbohydrate root reserves and crude protein and tannin in crownvetch forage, Coronilla varia L. Agronomy Journal, 60, 415-419.
LE ROUX, C.J.G., HOWE, L.G. and DU TOIT, L.P. (1988) A comparison of the dry matter yields of perennial legumes in the Dohne Sourveld, South Africa. Journal of the Grassland Society of South Africa, 5, 146-149.
MAYS, D.A. and EVANS, E.M. (1972) Effects of variety, seeding rate, companion species and cutting schedule on crownvetch yield. Agronomy Journal, 64, 283-285.
MILLER, D.A. and HOVELAND, C.S. (l995) Other temperate legumes. In : Barnes, R.F., Miller, D.A. and Nelson, C.J. (eds) Forages, 5th edn, Vol.1, An Introduction to Grassland Agriculture. pp. 273-281. Iowa State University Press, Ames, Iowa.
PEIFFER, R.A., McKEE, G.W. and RISIUS, M.L. (1972) Germination and emergence of crownvetch as affected by seed maturity and depth of planting. Agronomy Journal, 64, 772-774.
REYNOLDS, P.J., JACKSON, Jr. C. and HENSON, P.R. (1969) Comparison of the effects of crownvetch (Coronilla varia L.) and alfalfa hays on the liveweight gain of sheep. Agronomy Journal, 61, 187-190.
REYNOLDS, J.J. and SMITH, D. (1962) Trends of carbohydrate reserves in alfalfa, smooth bromegrass and timothy grown under various cutting schedules. Crop Science, 2, 333-336.
SHARP, W.C., SCHERTZ, D.L. and CARLSON, J.R. (1995) Forages for conservation and soil stabilization. In: Barnes, R.F., Miller, D.A. and Nelson, C.J. (eds) Forages 5th edn, Vol. II, The Science of Grassland Agriculture. pp.243-262. Iowa State University Press, Ames, Iowa.
TOWNSEND, C.E. and McGINNIES, W.J. (1972a) Temperature requirements for seed germination of several forage legumes. Agronomy Journal, 64, 809-812.