Weed Suppression Using Hairy Vetch Living Mulch in Forage Soybean Crops

Abstract

We conducted field experiments during the period 2011-2014 to evaluate the efficacy of hairy vetch (HV) living mulch on weed control in stands of forage soybean cultivated without herbicides. Soybean seed was planted in June, without tilling, into HV sod that had been sown in September of the previous year. The HV sods were chopped by disc harrow, prior to soybean seed germination, with the gang angle adjusted to prevent overturning of the sod. The dead HV sod formed by this procedure suppressed weed growth effectively in fields where pale persicaria, common lambsquarters, or slim smooth pigweed dominated, but was less effective in a field dominated by barnyard grass. If the disc harrow procedure was carried out within four days of soybean planting, soybean germination was not disturbed. We also found that a planting density of soybean-less than 12000/ha-brought about an increase in weeds, and consequently reduced soybean yields.