Weed suppression, weed seed bank and crop productivity influenced under tillage and mulches in maize-rapeseed cropping system

Crop productivity is seriously threatened by weeds, and poor management techniques may make the problem even worse. Hence, there is need to minimize weed severity and sustain crop productivity. The study aimed to minimize the weed severity, determine the status of weed seed bank and enhance crop productivity in maize-rapeseed cropping system. Therefore, the maize-rapeseed system was evaluated with three tillage practices in main plots [deep tillage (DT), reduced tillage (RT), and no-tillage (NT)] and two levels of crop residue mulch (CRM) in sub-plots [4 Mg ha- 1 mulch and bare land]. The results revealed that 41-52% of maize and 40-50% of rapeseed canopy, respectively, covered cropped land followed by weeds and mulch. While having more grasses and sedges, NT plots had 18.8-20.9% less broadleaved weeds. Contrarily, DT in maize and RT in rapeseed coupled with CRM substantially suppressed all groups of weeds resulted in higher maize grain yield (3.84-3.94 Mg ha -1) and seed yield of rapeseed (0.96-0.98 Mg ha-1). The CRM could suppress weeds by 62-68% in maize and 66-72% in rapeseed while increasing maize yield by 6-10% and rapeseed yield by 20-25% over NT. Weed seeds in NT were more concentrated (>80%) at 0-10 cm soil profile, while they uniformly distributed (0-30 cm) in DT and RT. Moreover, fewer weed seeds were recorded across the soil depths in mulch-adopted plots over bare land. Likewise, DT and RT coupled with CRM obtained significantly (p < 0.05) higher system productivity over NT and bare land. Considering the facts, DT and RT with CRM in the system suppressed weeds by 32.6-48.3%, minimized the weed seed bank in the active seed bank (0-5 cm) by 70% and gave 15.6-28.9% higher system productivity in the maize-rapeseed cropping system.