Enhancing the role of legumes: potential and obstacles.

Legumes have a potentially significant role to play in enhancing soil carbon sequestration. They can also have considerable additional benefits beyond their importance regarding nitrogen fixation and high protein feeds. These include positive impacts on biodiversity and soil quality. There is a great need for a strong focus on developing the role of legumes and their contribution to both the sustainable intensification of production and the livelihoods of smallholder farmers in many parts of the world. POTENTIAL OF LEGUMES TO ENHANCE CARBON SEQUESTRATION AND DELIVER CO-BENEFITS Legumes and carbon sequestration For a number of years, the potential importance of legumes in many agro-ecosystems, but also the limited extent to which this potential has been realized, has been recognized. Legumes do not just contribute in terms of food, feed and fertility, but are also important as fuelwood and with respect to carbon (C) sequestration. In this chapter we focus on the extent to which legumes can contribute to enhanced C sequestration and the delivery of co-benefits including greater biodiversity and reduced greenhouse gas (GHG) emissions. We also consider briefly the main reasons why legumes are currently underutilized and the prospects for a greater role in the future. Enhancing C sequestration in the soil is linked to increased biomass and hence to soil fertility. Raising fertility is possibly the most effective way of rapidly increasing C sink capacity. Clearly, one way of doing this is through increased addition of nitrogenous fertilizers. However, caution in the widespread use of nitrogenous fertilizers as an approach to increased productivity is appropriate for a number of reasons, including the potential