The growth of grain legumes into Australian farming systems has been increasing in the 1980’s. Part of their value in crop rotations is their ability to fix atmospheric nitrogen in symbiosis with Rhizobium. This may decrease the need for nitrogen fertilizer for crop following the legume crop. This is because some of the fixed nitrogen may be left in the legume crop residue after grain harvest and thus become available to the following crop. Subsequently legumes have a reputation of maintaining or increasing soil nitrogen status.

Many management practices of the farmer will influence the amount of nitrogen fixed by the grain legume crop and thus the amount left for the following crop. Practices like ground preparation, inoculation, fertiliser usage, irrigation and crop residue management all affect the amount of nitrogen fixed and left by the legume crop. The following review covers these and other management practices. As well, certain biological aspects of nitrogen fixation are discussed giving background to the effects of management practices