MULTIPURPOSE TREE PRUNINGS AS A SOURCE OF NITROGEN TO MAIZE UNDER SEMIARID CONDITIONS IN ZIMBABWE .2. NITROGEN-RECOVERY RATES AND CROP GROWTH AS INFLUENCED BY MIXTURES AND PRUNINGS
Pl. Mafongoya et al., MULTIPURPOSE TREE PRUNINGS AS A SOURCE OF NITROGEN TO MAIZE UNDER SEMIARID CONDITIONS IN ZIMBABWE .2. NITROGEN-RECOVERY RATES AND CROP GROWTH AS INFLUENCED BY MIXTURES AND PRUNINGS, Agroforestry systems, 35(1), 1997, pp. 47-56
Time of pruning application and mixing prunings of varying qualities c
ould be important management options to increase the rate of nitrogen
recovery from multipurpose-tree prunings that are used as a source of
nitrogen to crops. A field experiment was conducted in the semiarid zo
ne of Zimbabwe to test this hypothesis, using prunings of calliandra (
Calliandra calothyrsus) and leucaena (Leucaena leucocephala), alone an
d in mixtures, and maize (Zea mays) as the test crop. Time of pruning
application significantly improved N uptake, N recovery, and grain yie
ld of maize. Applying prunings of calliandra at maize planting was sig
nificantly better in terms of N uptake, N recovery, and grain yield th
an applying them four weeks after planting. However, with leucaena, ti
me of prunings application had no significant effects on;N recovery. M
ixing prunings of leucaena and calliandra had no effect on maize N upt
ake, N recovery, and grain yield. Split application of available pruni
ngs during the crop growth cycle had no effect on N recovery compared
to one-time application of entire amounts of prunings at planting.