Integrating zinc fertilisation with conservation agriculture enhances soil health, enzyme activities, and rice productivity

Context Conventional agricultural practices, particularly poor soil management and intensive tillage, have led to soil degradation in rice (Oryza sativa L.) systems. These practices reduce the bioavailability of essential micronutrients, such as zinc (Zn), thereby constraining grain yield and nutritional quality. Aims This study evaluated the effects of rice production systems (RPS), namely, direct seeded aerobic rice (DSAR), and puddled transplanted rice (PuTR), and different Zn application methods on soil health, soil enzyme activities, and rice productivity. Methods A 2-year field experiment (2017–2018) was conducted in Sialkot, Pakistan, comparing the following four Zn application methods: soil application (10 kg ha−1), seed priming with 0.01 M Zn solution, foliar application at 0.025 M, and a control (no Zn). Key results DSAR significantly improved soil organic carbon (SOC: 5−27%), microbial biomass carbon (MBC: 5−12%), microbial biomass nitrogen (MBN: 3−7%), and activities of key extracellular enzyme activities, viz. β-glucosidase (18−54%), chitinase (5−16%), acid phosphatase (26−132%), and leucine aminopeptidase (23−66%) across soil depths and years. Zn application methods further enhanced SOC and MBN, especially in the topsoil. Among Zn application methods, seed priming produced the highest grain yield in DSAR (5.06 t ha−1 and 4.75 t ha−1 during 2017 and 2018 respectively), whereas soil-applied Zn was the next-most effective in terms of grain yield in both rice production systems. Conclusion Zn seed priming, followed by soil and foliar application, significantly enhanced grain Zn concentration in DSAR, whereas soil-applied Zn was most effective for enhancing grain protein concentration in both PuTR and DSAR systems. Integrating conservation-based tillage with Zn management was shown to be synergistic, improving both soil health and rice productivity. Implications Healthy soils are essential for productive, nutrient-rich rice, yet conventional farming often depletes soil fertility. This study shows that direct-seeded rice combined with zinc application improves soil quality, boosts enzyme activity, and increases both yield and grain nutrition. These findings offer a practical strategy for sustainable rice production, supporting soil health and enhancing food security.