Plow down effects of different forage legume species, cultivars, cutting strategies and seeding rates on the yields of subsequent crops

Summary

Under some conditions the plow down of forage legumes increases the yield of subsequent crops, which is usually caused by improved soil N. However, better soil structure is also a contributing factor. Three experiments were conducted to measure the effect of legume plow down on the yield of subsequent corn crops grown at the Ottawa Research Station (ORS), Ottawa, Canada. In all experiments, corn yields were not affected by legume species, legume cultivars, and/or planting methods. Corn yields from barley plots receiving 0, 60, or 120 kg N ha⁻¹ did not differ until two years after establishment in one experiment and three years in another. The data from these experiments indicated that soil N was high at the ORS, which may inhibit N₂-fixation by forage legumès in the establishment year. Therefore, legume plow down was not beneficial to subsequent crops under these conditions.

Two other experiments were conducted to measure the effect of legume plow down on the yield of subsequent barley crops. In both experiments, barley yields in the field were not affected by legume type or legume seeding density. Greenhouse and field data indicated that the two cuts with removal strategy benefitted the most to succeeding crops. Data from the greenhouse test indicated that soil N levels were not low in the establishment year, and that some cultivars improved soil fertility more than others.