Organic manure and fertilizer N management strategies improve soil health at different growth stages of pearl millet under pearl millet-wheat sequence

Abstract

Background: Incorporating organic manure improves soil properties and crop productivity. A long-term study started in October 1967 examined the effects of farmyard manure and nitrogen fertilization on the soil at key growth stages of pearl millet in a pearl millet-wheat cropping system over its 51st cycle. Results: Applying 15 Mg of farmyard manure (FYM) per hectare in both growing seasons significantly boosted soil organic carbon (SOC), dissolved organic carbon (DOC), and key nutrients compared to one-season application. SOC levels reached 9.1–11.0% with FYM15, outperforming FYM10 and FYM5. The effectiveness order was FYM15 > FYM10 > FYM5 > FYM0. Chemical nitrogen fertilization also enhanced soil properties, with FYM15 improving DOC, available nitrogen, and enzyme activities during various growth stages. Conclusions: Principal component analysis (PCA) effectively distinguished soil variables and treatments, with β-glucosidase and arylsulfatase activity (ARA) showing the highest loading (0.294) in the first principal component (PC1), followed by dissolved organic carbon (DOC) at 0.292 and dehydrogenase activity (DHA) at 0.291. A strong polynomial relationship was noted between soil organic carbon (SOC) and various soil properties, with R² values between 0.93 and 0.99. The FYM15 x N120 treatment improved soil health in North-West India’s sandy loam soils during both seasons.