Effects of organic and inorganic amendments on weed management in sweet maize

Abstract

Field experiments were conducted to determine the effects of organic and<br />inorganic amendments on weed suppression in sweet maize cultivation (Zea mays<br />L.). A randomized complete block design was employed with four replicates per<br />treatment with each organic amendment used at half (x/2), single (x=10 t ha-1) and<br />double (2x) rates (organic fertilization: cow manure, poultry manure and barley<br />mulch; synthetic fertilizer (240 kg N ha-1: 21-0-0); and control). The highest<br />number and dry weight of weeds were recorded for double cow manure and<br />chemical fertilizer treatments. The cow manure treatments promoted weed<br />emergence and growth proportionally to the rate of application (x/2<x<2x). In the<br />presence of barley residues, weed biomass or density was reduced for the species:<br />redroot pigweed (Amaranthus retroflexus L.), common purslane (Portulaca<br />oleracea L.) and prostrate knotweed (Polygonum aviculare L.). Weed suppressive<br />effect of barley residues decreased with time following residue decomposition. The<br />barley mulch plots presented the highest values of Shannon-Weiner and Simpson<br />indices. These results indicate that green manure of barley are effective for the<br />suppression of some weeds in sweet maize.