Recovery of leucaena and dactyladenia residue nitrogen15 in alley cropping systems

Vanlauwe, B., Sanginga, N. & Merckx, R. (1998). Recovery of Leucaena and Dactyladenia residue nitrogen-15 in alley cropping systems. Soil Science Society of America Journal, 62(2), 454-460.

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 <l %. The cowpea plants in the leucaensand dactyladenia microplots contained 05 and l.lolo of lhe residueN in the lirst harvest. Sixteen and 9% of the residue N was recovered by the leucaena hedgerow in the first and second pruning following residue application. The dactyladenia hedges recovered maximally 3.1% of the residue N in a single pruning. The total N recovery in the leucaena microplots was =90% at 120 and 471 DAA, compared with 56 and 35%in the dactyladenia microplots. At 858 DAA 620% of the added leucsena N was accounted for, compared with 25% of the dactyladenia N. Residue quality was shown to have a major impact on the dynamics of applied residue N in alley cropping systems and will be an important factor in deciding which residue-supplying plant species to integrate into similar cropping systems.