11 - Soybean production and N fertilization

Abstract

Soybean (Glycine max (L.) Merr.) is among the most important legume plants, feeding a large number of people across the globe. It can establish a symbiotic association with its specific nitrogen (N) fixing bacterium, Bradyrhizobium japonicum, and acquires most of its essential N therefrom. Such a process is of great economical and environmental significance and can contribute to the health of human beings. However, the remaining part of soybean essential N comes from N-chemical fertilization, which is a quick method of providing plants with N. The important point about using N-chemical fertilization is its interference with the process of biological N fixation by soybean and its symbiotic rhizobia. If extra amounts of chemical N are used, the activity of B. japonicum and hence the amounts of the N fixed by the symbiotic rhizobia decrease. Accordingly, the appropriate rate of N chemical fertilization must be determined so that in combination with the process of N biological fixation the plant can absorb its essential N resulting in suitable growth and yield production. The most important details are presented and analyzed.