Quantitative Separation of Nitrogen and Non-Nitrogen Rotation Benefits for Maize Following Velvet Bean Under Selected Soil Management Practices

摘要

AbstractIt is increasingly known that factors other than legume-fixed nitrogen contribute to rotation benefit (yield advantage of legume/cereal over cereal/cereal). The contributions of nitrogen and such other factors were quantified to guide soil fertility management in legume/cereal systems. Under greenhouse conditions, the effects of returning first crop’s residue to the soil, crop sequence (velvet/maize, maize/maize) and nitrogen-fertilizer level on yield of second maize were used to separate rotation benefits into nitrogen and non-nitrogen factors, while the corresponding effects of crop sequence, mycorrhizal inoculation and phosphorus-targeted fertilization in a parallel experiment were used to disaggregate the non-nitrogen effects. Crop residue and velvet/maize had positive effects on soil nitrogen and maize yield. Nitrogen fertilizer had optimal effects at 60?kg?ha?1, while phosphorus enhanced maize yields the most when no essential nutrient was limiting. Rotation benefit was lower without (13.59%) than with (33.27%) residue. Non-nitrogen rotation benefit was 37.5%. Relative contributions of nitrogen, phosphorus, other nutrients, mycorrhiza and not-considered factors were, respectively, 34, 9, 6, 21 and 30% without residue and 68, 4, 3, 10 and 15% with residue. Crop residue management has, therefore, a strong underlying influence on legume-to-cereal rotation benefit and the relative contribution of its components.]]>