Conservation tillage and weed management in smallholder agriculture: Issues and opportunities

Constraint to effective weed management is one of the major reasons for limited adoption of conservation tillage systems in smallholder farming in India. Conservation tillage (CT) has variable effects on soil weed seed bank dynamics, seed germination and seedling emergence, and efficacy of weed control measures. In CT system, a large portion of the weed seeds accumulates in the upper soil layer in contrast to conventional tillage, where large proportion of seeds are buried and maintained in deeper soil layers. In general, CT system increases populations of perennial and summer annual grass where as densities of large seeded dicot species and winter annuals decreases. Due to restricted tillage options, weed control in CA system is largely depends on use of herbicides which often fail to provide adequate weed control in presence of crop residues on soil surface. The present paper highlights the weed management issues and opportunities in CT systems