Weed Management Options for Conservation Agriculture Farmers

Weeds have been identified as the major agronomic problem associated with arable crop production in conservation agriculture systems. Manual weeding and hand pulling are by far the most common weed control methods used in maize production, whilst chemical weed control is relatively uncommon in Zimbabwe's smallholder farming systems. In Zimbabwe, the key to conservation agriculture revolves around weed control. An experiment was done to evaluate the effect of manual and chemical weed control strategies on (i) weed density and biomass, (ii) total labour requirements for weed control, (iii) maize biomass and grain yield and (iv) the economics of weed control. The trials were done at four sites in Zimbabwe's Highveld area in the 2007/8 rainy season. Results from the different sites show that weed abundance was not significantly affected by the different weed control strategies that were used in this study. However the different weed control strategies resulted in differences in labour requirements and economic returns. This study showed that using tank mixes of glyphosate and atrazine at planting is the most effective and economically feasible weed control strategy.