Effect of tillage and weed control approaches on soil biological health and rice crop performance under conservation agriculture

Conservation agriculture, a climate-resilient approach, improves holistic soil health but is often constrained by severe weed challenges. To assess the effect of tillage and weed management practices on soil biological health, a field experiment was conducted during the kharif seasons of 2019 and 2020 at the Research cum Instructional Farm, Indira Gandhi Krishi Vishwavidyalaya, Raipur (Chhattisgarh). The experiment with the rice variety “IGKV R1” was laid out in a split-plot design with five tillage practices as main plots, namely two conventional transplanted rice [CT(TPR)], one conventional direct-seeded rice [CT(DSR)], zero tillage (ZT) and zero tillage with residue retention (ZT+R) and three weed management practices as sub-plots, replicated thrice. The results revealed that the conventional transplanted system [CT(TPR)] recorded the highest economic yield, which was of 7.66 % higher than that of ZT+R. Soil biological properties, including dehydrogenase activity (DHA), fluorescein diacetate (FDA) and bacterial, fungal and actinomycete populations, showed significant variation across the observation stages. These parameters increased after herbicide application and declined towards harvest. Among the tillage practices, ZT+R recorded the highest soil biological activity, whereas CT(TPR) recorded the lowest, indicating greater sustainability under conservation agriculture. Among weed management practices, integrated weed management (IWM) i.e. oxadiargyl 80 g ha-1 pre-emergence (PE) followed by hand weeding at 25 days after sowing (DAS)/T resulted in superior performance across all parameters and produced 47 % higher grain yield than the weedy check. Therefore, the combined adoption of ZT+R and IWM is socio-ecologically acceptable and recommended for sustainable rice production.