Theme 02: Grass-Legume Mixtures
Description
Soil mineral N and DM yield of five forage legume species were investigated in field experiments at two sites in Sweden, established 1997. The species studied were: red clover (Trifolium pratense L.), lucerne (Medicago sativa L.), white clover (Trifolium repens L.), galega (Galega orientalis Lam.) and lotus (Lotus corniculatus L.), all grown in grass-legume mixed swards. No nitrogen was applied to the legumes. Results from two years of ley (1998 and 1999) are presented. Correlation was found between accumulated mineral N in the soil in the autumn and the total seasonal DM yield of the legume fraction of mixed grass-legume swards under temperate conditions. In the first year of ley, the correlation was stronger than in the second year ley. The levels of mineral N in the soil were highest in spring first year of ley at both sites and thereafter the levels decreased until autumn of the second year of ley. Legumes alone showed a poor correlation between soil mineral N in the autumn and DM yield of the legume both years of ley. Most likely the N leaching is taking place at the spring thaw, not during winter when the ground is frozen. In conclusion, when high proportions of legumes in the harvest occur, there could be an environmental risk of N leaching.
Included in
Correlation between Yield of Forage Legumes in Grass Mixtures and Accumulation of Soil Mineral Nitrogen in Sweden
Soil mineral N and DM yield of five forage legume species were investigated in field experiments at two sites in Sweden, established 1997. The species studied were: red clover (Trifolium pratense L.), lucerne (Medicago sativa L.), white clover (Trifolium repens L.), galega (Galega orientalis Lam.) and lotus (Lotus corniculatus L.), all grown in grass-legume mixed swards. No nitrogen was applied to the legumes. Results from two years of ley (1998 and 1999) are presented. Correlation was found between accumulated mineral N in the soil in the autumn and the total seasonal DM yield of the legume fraction of mixed grass-legume swards under temperate conditions. In the first year of ley, the correlation was stronger than in the second year ley. The levels of mineral N in the soil were highest in spring first year of ley at both sites and thereafter the levels decreased until autumn of the second year of ley. Legumes alone showed a poor correlation between soil mineral N in the autumn and DM yield of the legume both years of ley. Most likely the N leaching is taking place at the spring thaw, not during winter when the ground is frozen. In conclusion, when high proportions of legumes in the harvest occur, there could be an environmental risk of N leaching.
