Abstract:
Three field experiments were conducted in two seasons in Zimbabwe to study the effects of rate and method of
placement of NPK fertilizer on productivity of maize and the emergence and growth of weeds. Compound D (8% N,
14% K2O, 7% P2O5, 6,5% S) was applied at 75, 150 and 225 kg ha1 using three placement methods viz. spot
placement, banding and broadcasting in Experiment 1. The three placement methods were combined with four
weed-free period and weedy periods in Experiment 2 and 3. Maize yield was highest at 150 kg ha1 of compound D
in Experiment 1. Banding consistently attained the highest maize grain yield, followed by spot placement and
broadcasting. Early maize growth and grain yield data suggested that spot placement may reduce the yield
response of the maize to fertilizer in water limited environments by predisposing maize plants to higher levels of
moisture stress, when compared to banding. Spot and band placement increased radiation interception and early
growth of maize and reduced the emergence, growth and seed production of weeds, compared to broadcasting;
however the effects of fertilizer placement on weeds did not significantly affect the duration of critical period for
weed control required to avert yield loss in maize. Our results suggest that smallholder farmers may maximize the
benefits, of increased yield and suppression of weeds, derived from scarce fertilizer/manure resources by using
precise methods of placement, more so with banding than spot placement.
