Strategic management of nano-fertilizers for sustainable rice yield, grain quality, and soil health

Conventional fertilizers, although widely available, are relatively low in nutrient use efficiency and cause serious environmental concerns like eutrophication, greenhouse gas (GHG) emissions, nitrate poisoning, and soil pollution. With this in mind, a randomized block design (RBD) experiment was conducted in an experimental field taking 10 treatments and 3 replications to investigate the effects of integrated approaches of nano-formulated DAP fertilizer applications on rice growth, yield, and nutrient use efficiency over conventional approaches. The result revealed that plant height, panicle length, number of tillers hill −1 , total number of grain panicle −1 , and root length were maximum in T 10 treatment (50% of the soil test recommended doses (STD) for N and P + seedling root dipping (SRD) with nano DAP at 5 mL L −1 + twice foliar sprays (FS) with nano DAP at 4 mL L −1 at 25 and 45 DAT (date after transplanting). The highest mean grain yields (4.12 and 4.05 Mg ha −1 ) and nutrient uptake were recorded in the T 2 treatment (100% STD), but this was at par with T 10 treatment. The highest benefit–cost ratio (2.26) was recorded in T 10 , which was 3.5% higher than T 2 . N and P agronomic use efficiency (AUE) ranged from 7.5% to 31.5% and 15% to 63%, and recovery efficiency (RE) ranged from 30% to 94.2% and 11.2% to 90.4%. The highest nutrient use efficiency was recorded with T 10 , followed by T 9 , and lowest in T 4 . Post-harvest soil pH and available N and P were significantly highest in T 10 . Soil MBC, MBN, MBP, urease, and phosphatase activity were found significantly higher in T 2 , followed by T 10 . The integrated application of 50% STD for N and P + SRD with nano DAP at 5 mL L -1 + twice FS with nano DAP at 4 mL L −1 at 25 and 45 DAT application can be a suitable substitute for conventional DAP and urea for rice in climate-smart agriculture as it possibly reduces environmental pollution while undisturbing crop yield over the 100% STD.