Crop Mulches for Increased Weed Control and Rice Productivity

A study was conducted to determine the influence of mulches of rice (R), maize (Mz), mucuna (Mc) and cymbopogon (C) on weed growth and rice yield. Twelve mulch treatments included MzRC, RMcC, MzMC, MzRMc, MzRC + one hand rogueing of weeds (hr), RMcC + hr, MzMcC + hr, MzRMc + hr, MzRC + one hand hoeing of weeds (hh), RMcC + hh, MzMcC + hh and MzRMc + hh, 2hh, 3hh, Butanil +1hh and a weedy check in a randomised complete block design (RCBD) with three replicates. The study was conducted both on-station and on-farm (2014). CMcRMz species were each planted in 24 plots under a RCBD replicated thrice and 3 crops uprooted from the plots were combined in equal proportions of different stover into four mulches (MzRC, RMcC, MzMcC & MzRMc). The experimental site was ploughed, divided into 48 plots under RCBD replicated thrice and the mixed mulches were applied (10-12.Mt ha-1) to 12 plots at planting. Higher rice growth was recorded under MzMc than RC mulches with or without a post mulch weed control. RC based mulches most effectively reduced weed density and biomass followed by MzMc mulches. 2hh and MzRMc mulch + 1hr produced similar rice yield but lower rice yield was under RMcC and Butanil + 1hh. Rice growth and tiller development reduced under the weedy check giving zero yields. The highest Striga was under Butanil + 1hh (8 Striga), followed by 3hh and 2hh (3 & 2 Striga). No Striga was recorded under cymbopogon mulches and weedy check. The highest returns on investment (ROI) were under 2hh (0.52 & 0.43) at the two sites and MzRMc + hr recorded high ROI (0.47) on station, similar to 3hh on-farm. Maize, rice, cymbopogon and mucuna have high potential to produce bio-herbicides with high rice yields.