Search

Conservation agriculture (CA) is advocated as a management system for sustainable productivity, while preserving the environment simultaneously. CA has many advantages, but weed management is regarded as one of its biggest challenges. This study reports on the temporal variation in weed occurrence and biomass under conservation and conventional farming practices. The treatment design was a split-split plot, with a randomised complete block design with three blocks as replicates. Tillage was the main plot factor (reduced tillage [RT] and conventional tillage [CT]), and treatments (a combination of cropping systems and fertilizer levels) were treated as the sub-plot factor. Only cultivation year (F(2.48) = 9.12, p < 0.001) and the cultivation year and tillage interaction (F(2.48) = 22.41, p < 0.001) significantly affected weed biomass. Weed biomass and species diversity increased under RT from cultivation year 3 to 5. Under CT weed biomass had a slight downward trend and species composition was similar across the three years with two dominant weeds representing between 87.2 and 75.1% of total weed biomass. The results suggest that tillage practices can affect both the biomass and diversity of weeds. It is therefore important that practitioners understand such variation and apply weed management practices accordingly. Key words: Conventional tillage, reduced tillage, weed composition, weed dynamics.