Effects of inter-row hoeing and fertilizer placement on weed growth and yield of winter wheat

Inter-row hoeing is known to control tap-rooted and erect weed species more effectively in winter wheat than weed harrowing. However, little is known about its effectiveness for use in the spring in winter wheat grown at wide row spacing (240 mm) under the influence of different placement of fertiliser. Two field experiments, one in 1999 and one in 2000, were conducted to study the influence of fertiliser placement, timing of inter-row hoeing, and driving speed on the weeding effect on different weed species and crop growth. Placement of fertiliser below the soil surface improved crop growth and grain yield in both years compared with placement on the surface, but weeds surviving hoeing were not more suppressed by the improved crop growth. Timing was not important in the one experiment, whereas hoeing twice with beginning in early April was most effective in the other experiment where weed growth over the winter had been vigorously. Driving speed had no influence on either the weeding effect or the yield, except for one case where increasing speed reduced the effect against well-developed weeds. As compared to non-weeded reference treatments, inter-row hoeing reduced total weed biomass by 60-70% and tap-rooted and erect weed species in particular by 50-90%. Sowing at 240 mm row spacing yielded less than 120 mm (Danish standard), and inter-row hoeing for winter wheat needs to be adapted to narrower row spacing to avoid such yield declines.