MULTIPURPOSE TREE PRUNINGS AS A SOURCE OF NITROGEN TO MAIZE UNDER SEMIARID CONDITIONS IN ZIMBABWE .1. NITROGEN-RECOVERY RATES IN RELATION TO PRUNING QUALITY AND METHOD OF APPLICATION
Pl. Mafongoya et Pkr. Nair, MULTIPURPOSE TREE PRUNINGS AS A SOURCE OF NITROGEN TO MAIZE UNDER SEMIARID CONDITIONS IN ZIMBABWE .1. NITROGEN-RECOVERY RATES IN RELATION TO PRUNING QUALITY AND METHOD OF APPLICATION, Agroforestry systems, 35(1), 1997, pp. 31-46
When multipurpose-tree (MPT) prunings are used as a source of nitrogen
to annual corps in agroforestry systems, it is important that high le
vels of N recovery are attained. In order to test the effect of prunin
g quality and method of pruning application on N-recovery rates, a fie
ld experiment was conducted using prunings of five MPT species and two
methods of application (surface versus incorporation). There was an i
nteraction of pruning quality and method of pruning application on N r
ecovery and maize grain yield. For most MPT species used, incorporated
prunings gave high nitrogen recovery compared to surface applied prun
ings. In order to achieve synchrony between N supply from prunings and
N demand by a maize crop, relatively large amounts of N should be rel
eased into the soil before peak N demand by the maize crop. This could
be achieved by incorporating adequate quantities of high quality prun
ings such as those of Cajanus cajan and Leucaena leucocephala.