Effect of management practices for Stylosanthes hamata (L.) Taub. biomass cover on the weed species in different direct-seeding, mulch-based cropping systems

Abstract

Weed management is a major challenge for smallholders’ adoption of conservation agriculture techniques. The phytological composition and weed biomass in five direct‐seeding cropping systems based on the millet–groundnut rotation, with permanent cover provided by Stylosanthes hamata (L.) Taub., were evaluated after 3 years in western Senegal. A transect was used to determine the phytological composition. The weed biomass was measured in five quadrats in the middle and at the end of the plant growth cycle. This study shows that S. hamata ground cover does not allow the effective control of weeds; high weed infestation was recorded in all direct‐seeding cropping systems (58–75% of the ground cover). A high diversity of weed species was observed in all treatments, dominated by Eragrostis ssp. and Dactyloctenium aegyptium Beauv. Cutting back and removing the aboveground biomass reduced the ground cover provided by S. hamata, lowered the weed species diversity and favored heliophilous species such as Eragrostis tremula but did not reduce weed infestation. Animal manure application did not, in the short term, affect the composition or structure of the weed species. However, it favored weed development and increased aboveground biomass. In the long term, this could affect weed seedbank and structure. Cutting back and removing the aboveground biomass of S. hamata resulted in lower weed diversity and higher crop yield. To achieve effective weed control, additional research on management techniques that would focus on the combination of cutting back vegetation and weeding along the crop seeding line will be needed.