Isotopic evidence of the transfer of nitrogen fixed by legumes to coffee trees.

The use of isotopic methods has made it possible to quantify the contribution of nitrogen fixed by a coffee plantation. Thanks to the use of the natural 15N abundance assessment technique, we were able to show that, in field condition, roughly 30/ of the nitrogen effectively fixed by a legume (including biomass, roots and root exudates) were transferred to the associated coffee trees. The quantities of N transferred by legume prunings to sole coffee trees were measured to evaluate the amount of N transferred to coffee via litter fall or soil.