Recovery of leucaena and dactyladenia residue nitrogen15 in alley cropping systems

Quantification of the fate of residue N is essential in low-input tropical cropping systems for the development of management practices that optimize N-use efficiency. The recovery of N from 15N-labeled leucaena (Leucaena leucocephala (Lam.) de Wit) and dactyladenia (Dactyladenia barteri (Hook f ex Oliv.) Engl.) leaf residues was followed in the soil, crop, and hedgerow of the respective alley cropping systems during three maize (Zea mays L.) and two cowpea (Vigna unguiculata L. Walp. subsp. Unguiculata) seasons. More residue N was recovered in the top 5 cm of soil in the leucaenr thsnin the dactyladenia microplots during the first 471 d after residueapplicetion (DAA). The first maize crop recovered 8, 6 and 5.2% ofthe N from leucaena and dactyladenie, respectively, while the two subsequent crops recovered