Weed seedbank, above-ground weed community and crop yields under conventional and conservation agriculture practices in maize-wheat-mungbean rotation

Weeds are the major biological barriers to achieving higher yields in agro-ecosystem. We aimed to determine weed community (seedbank and aboveground) and crop yield responses to conventional tillage (CT) and different types of conservation agriculture (CA) practices with variable nitrogen (N) doses in a maize (Zea mays L.)-wheat (Triticum aestivum L.)-mungbean (Vigna radiata L.) rotation. After 8 years of implementation, CA practices including zero-tilled (ZT) permanent narrow-bed with crop residues and 100% required N (PNB + R + 100 N), and ZT permanent broad-bed with residues and 100% required N (PBB + R + 100 N) had a lower weed seed density by 45% at 0-7.5 cm and 53% at 7.5-15 cm soil layers than CT. CT promoted dominance of Cyperus rotundus L., Cyperus esculentus L. and Dinebra retroflexa (Vahl) Panz. while, specific CA practices (PNB + R + 100 N and PBB + R + 100 N) promoted dominance of Digera arvensis Forsk. and Melilotus indicus (L.). Compared to PNB + R + 100 N and PBB + R + 100 N, CT seedbanks had 41-46% higher ecological dominance, which is an indicator that delineates dominance of few specific weed species. The PBB + R + 100 N also had a lower total above-ground weed density in maize-wheat-mungbean rotation by 34% (mean of years) than CT. The PBB + R + 100 N had 31.1% higher system productivity over CT. Thus, PBB + R + 100 N could reduce the weed seed density in the soil and above-ground weeds and increase crop yields for sustainable crop production in maize-wheat-mungbean rotations.