Crimson clover in pure stands yields 2.1 to 5.0 t DM/ha (Albayrak et al., 2013; Ross et al., 2009; Gilbert et al., 1992), which is much lower than for red clover (up to 19 t DM/ha in the USA). Under Mediterranean conditions, crimson clover sown in a mixture with Italian ryegrass yielded 4.7 t DM/ha in rain-fed stands and 6.3 t DM/ha under irrigation (Martiniello, 1999).
Crimson clover is a versatile fast-growing legume. It establishes from spring or summer seedlings. It can be sown (drilled or broadcast) alone or in combination with small grain crops or grass on a well-prepared seedbed, no deeper than 0.6 cm in clayey soils and 1.5 cm in sandy ones. Trifolium incarnatum can be mixed with other forage legumes such as vetches (Lathyrus spp), subterranean clover (Trifolium subterraneum), red clover (Trifolium pratense) and black medic (Medicago lupulina). Crimson clover can be sown with oats (Avena sativa), rye (Secale cereale), and annual ryegrass (Lolium perenne ssp. multiflorum) (Young-Mathews, 2013).
Crimson clover can be used either as a winter or a summer annual.
When it is intended as a winter annual, crimson clover is sown in late summer, at least 6 weeks before the first frost. It grows until frost occurs, provides fodder in November and resumes growth immediately after winter (February-March). It provides good soil cover during winter, good weed control and an early grazing fodder to livestock in early spring. In Western France, crimson clover is available a month earlier than red clover and 6 weeks earlier than alfalfa (GNIS, 2014; SARE, 2008; Ball et al., 2000). As a winter annual, crimson clover can be sown in association with a winter annual grass. The grass should be cut or grazed to prevent it from shading out crimson clover. Winter crimson clover can provide valuable green manure and is suitable for rotations: it can be first harvested or grazed by livestock and then ploughed in the soil to provide N to the subsequent summer crop (maize, wheat, cotton, etc.) (Young-Mathews, 2013).
Crimson clover as a summer annual is sown in May or June. It can be sown alone, once the risk of frost is over, to be harvested for hay in autumn (Young-Mathews, 2013). Crimson clover can be overseeded into a warm season perennial grass which should be removed by grazing, burning, or mowing prior to planting the clover (Ball et al., 2000).
Grazing and cutting
Crimson clover can be grazed or cut, but grazing or cutting should not start before the plants are 10-15 cm high and should leave at least an 8 cm high stubble. Trifolium incarnatum does not withstand overgrazing, though a constant grazing pressure at a moderate stocking rate may be beneficial to the plant as it limits fungal diseases (MSUcares, 2014). Though there is a low risk of bloat with crimson clover, hungry animals should not enter the stand and it is recommended to provide dry hay during periods of lush growth (Ball et al., 2000). Livestock can graze crimson clover until the blooming stage is reached. They must then be removed from the stand to allow reseeding. Once mature seeds have been dropped, livestock can re-enter the stand. Another possibility is to let crimson clover regrow and cut it for hay in summer. The stands can be grazed late in autumn and winter at moderate stocking rates (MSUcares, 2014).