Winter cover crops and fertiliser effects on the weed seed bank in a low-input maize-based conservation agriculture system

Abstract

This study investigated the effects of grazing vetch (Vicia dasycarpa L.) and oat (Avena sativa L.) cover crops and fertiliser on the seed bank of some problematic weeds in a maize-based conservation agriculture system. Soil sampling for seed bank analysis was carried out at the 0–5 and 5–20 cm depths after four years of rotations. The winter cover crops reduced the seed-bank density of Digitaria sanguinalis (L.) Scop., Eleusine indica (L.) Gaertn., Amaranthus retroflexus L. and Datura stramonium L. in the 0–5 cm depth by 30–70%. Vetch was more effective on depleting the D. sanguinalis seed bank than oat. Fertiliser application reduced the A. retroflexus seed bank by 41.6% in the weedy fallow, but had no significant effect in plots grown to the cover crops. The winter cover crops did not significantly affect seed-bank weed species diversity.