The effect of row spacing and weed density on yield loss of chickpea

The adoption of no-till farming and the desire to maintain stubble cover when sowing legumes in northern New South Wales and southern Queensland have resulted in an increase in commercial row spacing for chickpea (Cicer arietinum L.). This paper examines the effects of increasing crop row widths on weed competition in chickpea crops. Weed densities of 0, 2, 4, 8, 16, and 32 plants/m(2) of wild oats (Avena sterilis ssp. ludoviciana) and turnip weed (Rapistrum rugosum) were established with chickpea crops planted with either 32 or 64 cm row configurations in northern New South Wales during 1996 and 1997. A rectangular hyperbolic model adequately represented the loss in chickpea yield with increasing density of either weed. Even low densities of <10 plants/m(2) caused large (approx. 50%) reductions in yield, particularly with turnip weed. In these experiments, weed-free yields were higher when chickpea was sown in 32 cm rows compared with 64 cm rows, but weeds caused no greater loss in crop yield with the wider row spacing. The results of this work show that the use of wide rows has minimal impact on weed competion in northern chickpea crops.