Crop residue retention suppresses seedling emergence and biomass of winter and summer Australian weed species

Crop residue retention could affect the emergence and biomass of weeds in different ways. A summer and winter pot study was conducted to evaluate the effect of different amounts of sorghum and wheat residue on the emergence and biomass of 12 summer and winter Australian weeds. The equivalent amount of sorghum residue to 0, 1, 2, 4 and 6 t/ha was used in the summer study and winter weed seeds were covered with wheat residue equivalent to the amount of 0, 1, 2, 4 and 8 t/ha in the winter study. The emergence and biomass of Amaranthus retroflexus and Echinochloa colona was not affected by sorghum residue treatment. For other summer weeds, the use of the 6 t/ha sorghum residue treatment resulted in 59–94% reductions in biomass compared to no-sorghum residue retention. Similarly, the application of 8 t/ha wheat residue in the winter study resulted in a reduced biomass of 15–100% compared to no-crop residue treatment. The results demonstrated the high potential of using crop residues in eco-friendly weed management strategies, such as harvest weed seed control tactics.