Does soya bean really add nitrogen to the soil? : chemicals & fertiliser

The statement is often made that soya bean adds nitrogen to the soil through its symbiotic nitrogen-fixing ability with Rhizobium bacteria. Farmers observe it as vigorous growth of maize following a soya bean crop and then ascribed it to the additional nitrogen. Some research confirmed that a person needs to apply an amount of nitrogen to maize following maize, to match the yield of maize following soya bean without any addition of nitrogen. This conclusion is, however, wrong for most cases as some research has shown that soya bean is nitrogen-neutral. The soil, after the soya bean crop, is left with about the same amount of nitrogen it initially had. What most likely happens, is an improvement in the efficiency of nitrogen uptake by the following maize crop from the soil.