Grain legume rotation benefits to maize in the Nigerian savanna

Understanding the contributions of fixed-N and other rotation effects is essential in reducing energy use and pollution potential of inorganic fertilizer usage and to understand the process by which a legume benefits a non-legume grown in rotation. Two rotation cycles were evaluated to separate the fixed- N from other rotation effects of soybean and cowpea, natural fallow and maize on subsequent maize. The experiment was laid out in a split-plot design. The legumes fixed between 16 and 50 kg N/ha of their total N and had an estimated N contribution to soil ranging from -22 to 3 kg N/ha depending on the ratio of N derived from atmosphere and N harvest index. On average, maize following legumes had higher grain yield of 1.3-fold and NFRVs of 28 kg/ha compared with maize after maize. The correlations between soil microbial C and N, and crop yield indicate that these soil quality parameters can be used to predict yield. This book is essential for graduate students and experts in the fields of soil fertility/microbiology studying the contributions of legumes to soil quality and the mechanisms by which they benefit cereal crop grown in rotation.