Influence of nano-zinc oxide and fortified rice residue compost on rice productivity, zinc biofortification, zinc use efficiency, soil quality, zinc fractions and profitability in different rice production systems

Abstract

Transplanted rice (TPR) faces several limitations, including deteriorating soil quality, zinc (Zn) deficiency, low use efficiency of zinc sulfate (ZnSO4), water scarcity and escalating labor costs, which are dictating the shift toward alternate production systems like direct-sown rice (DSR) and aerobic rice (AR). However, this shift affects soil Zn dynamics and Zn availability to crops. This study was conducted to compare the effectiveness of Zn nutrition (ZnSO4 as soil application and zinc oxide nanoparticles (ZnO NPs) as seed priming alone or with foliar spray) and fortified organic manures (farm yard manure and rice residue) on the rice productivity, Zn use efficiency, grain biofortification, soil quality, Zn fractions and profitability under TPR, DSR and AR. The application of ZnO NPs and fortified rice residue compost significantly improved the yield traits (437 productive tillers m−2 and 186 filled grains panicle−1), grain weight (6.27 Mg ha−1), grain Zn fortification (33.41 mg kg−1) and Zn fractions in all rice production systems. The AR was found to be more encouraging in improving soil organic carbon (11.3%), dehydrogenase activity (21.96%), microbial biomass carbon (17.31%) and DTPA-Zn (10.57%) than TPR and DSR. ZnO NPs seed priming and fortified rice residue resulted in superior zinc use efficiency in both TPR and DSR. The maximum benefit-cost ratio was obtained in DSR with ZnO NPs and fortified rice residue compost. Altogether, DSR with seed priming and foliar spraying of ZnO NPs and fortified rice residue can be a more efficient way to enhance rice productivity, grain Zn fortification and profitability.