The response of weed community in soybean with conventional and conservation tillage systems on rainfed Vertisols

Abstract

A change in tillage system from conventional to conservation tillage may influence weed population, diversity and weed seed distribution in the soil profile. Therefore, a field study was conducted during 2009 through 2011 to investigate the effects of tillage system. The number of grassy weeds was least in the no-tillage (NT), reduced till (RT) and mould board plough (MB) treatments compared to the conventional till (CT) treatment. More dicot weeds were recorded in the RT and NT plots than the CT. Averaged over seasons, the CT and MB treatments had 17–30% more weed species than RT and NT treatments. Treatments NT, RT and CT had more weed seeds in 0–5 cm soil depth than the MB. The trend in 5–15 cm soil depth was MB > CT > RT = NT. Tillage systems had significant effect on soybean seed yield in one of the 3 years. Averaged over years, the CT treatment had the lowest seed yield (458 kg ha⁻¹), significantly lower than the MB and RT treatments (522–550 kg ha⁻¹). Seed yields were lower with one (452 kg ha⁻¹) than two (566 kg ha⁻¹) weeding operations. Our results indicate conservation till systems as a suitable option for soybean grown on Vertisols.

Keywords:

• mould board plough
• reduced tillage
• seed stratification
• weed diversity
• weed seedbank