Due to their role in improving soil fertility, grain legumes can be integrated into farming systems as part of soil fertility management. This offers a potential pathway towards sustainable intensification. In this chapter we focus on how to maximize biological nitrogen fixation and yields of grain legumes through soil and nutrient management options. We review existing literature on optimal conditions for legume cultivation and biological nitrogen fixation in grain legumes, and then discuss recent studies in biological nitrogen fixation in the Guinea Savanna zone of Ghana. We conclude by considering future trends in grain legume research.