Weed population dynamics in wheat as affected by Astragalus sinicus L. (Chinese milk vetch) under reduced tillage

An understanding of the weed population dynamics under reduced tillage systems is essential in order to achieve successful weed control without using herbicides under a sustainable soil management system. A switch from conventional to conservational tillage alters the weed species composition and temporal pattern of emergence of weeds. A two-season experiment was conducted in 2000/2001 and 2001/2002 winters to determine the effect of Astragalus sinicus L. as a cover crop in wheat under minimum tillage (MT) and no-tillage (NT) as compared to conventional tillage (CT) on a clay loam soil. In both seasons, total weed biomass was greater in the no-tillage system and the continuous cultivation significantly reduced all the major weed species. Row seeding of A. sinicus resulted in lower weed biomass than broadcasting. Repeated cultivation affected wheat until the heading stage irrespective of the tillage or presence of the cover crop but the effect on ripening stage was not significant. Although, NT resulted in the lowest yield under the given conditions, successive cultivation of wheat with the incorporation of the cover crop did not affect the wheat yield significantly. An increase in the prevalence of weeds was observed as the degree of tillage was reduced but successive cultivation reduced the overall biomass significantly. The results showed the significance of a row seeded cover crop with wheat under MT in order to achieve comparable yield with CT.