Legume Identity and Timing of Incorporation Effects on Soil Responses to Green Manure
Challenges to sustainable agriculture include optimizing nitrogen (N) availability, maintaining profitability by reducing input costs, such as synthetic N fertilizers, and minimizing the loss of nitrate-N. Production of a legume green manure in a crop sequence is a typical method used to reduce or eliminate the need for applying synthetic N fertilizer to succeeding crops. Legumes or legume/small grain mixtures are often used as green manures because of the symbiotic association of most legume species with N fixing Rhizobium bacteria. The dynamics of nitrogen (N) mineralization in the soil after legume incorporation are complex. To contribute adequate amounts of plant-available N to the subsequent crop, the incorporated green manures must decompose sufficiently and in synchrony with the N demand of crops such as corn.