Promotion of weed species diversity and reduction of weed seedbanks with conservation tillage and crop rotation.

摘要

In a 6-year study on four farms (36 fields) in Ontario, Canada, we tested the effects of tillage (mouldboard, chisel plough, no tillage) and crop rotations (continuous corn [maize], corn-soyabean, corn-soyabean-winter wheat) on emerged and seed bank weed species diversity and density. Aside from the imposed experimental treatments, all other management was generally consistent among farms. Tillage had the greatest effect on weed diversity and density. No tillage promoted the highest weed species diversity, chisel plough was intermediate, and mouldboard plough resulted in the lowest species diversity. These results are consistent with ecological succession theory. The increase in weed species diversity resulted from 20 species being associated with no tillage systems, 15 of which were winter annuals, biennials, or perennials. Emerged weed density was affected only by tillage. Over 6 years, seed bank declined in no-tillage systems from 8000 to 41 000 seeds m-3. Crop yields were not affected by tillage or crop rotation. In practical terms, reduced tillage in combination with a good crop rotation may reduce weed density and expenditures on weed management..