Manipulating Crop Row Orientation to Suppress Weeds and Increase Crop Yield

摘要

Crop rows oriented at a right angle to sunlight direction (i.e., eastwest within the winter cropping system in Western Australia) may suppress weed growth through greater shading of weeds in the interrow spaces. This was investigated in the districts of Merredin and Beverley, Western Australian (latitudes of 31p and 32pS) from 2002 to 2005 (four trials). Winter grain crops (wheat, barley, canola, lupines, and field peas) were sown in an eastwest or northsouth orientation. Within wheat and barley crops oriented eastwest, weed biomass (averaged throughout all trials) was reduced by 51 and 37%, and grain yield increased by 24 and 26% (compared with crops oriented northsouth). This reduction in weed biomass and increase in crop yield likely resulted from the increased light (photosynthetically active radiation) interception by crops oriented eastwest (i.e., light interception by the crop canopy as opposed to the weed canopy was 28 and 18% greater in wheat and barley crops oriented eastwest, compared with northsouth crops). There was no consistent effect of crop row orientation in the canola, field pea, and lupine crops. It appears that manipulation of crop row orientation in wheat and barley is a useful weed-control technique that has few negative effects on the farming system (i.e., does not cost anything to implement and is more environmentally friendly than chemical weed control).