Straw return with nitrogen fertilizer promotes rice yield through change in nutrient dynamics within soil aggregates in saline sodic soils.

Purpose: Saline sodic soils pose challenges for crop growth due to their high soil salinity, poor structure, and low nutrient content and effectiveness. As a result, there has been increasing interest in using straw return to the field as a means to enhance productivity. However, the impact of straw return and nitrogen fertilization on soil aggregates and nutrient dynamics in saline sodic soils has not been fully understood yet. Methods: The present study conducted a 3-year positional experiment to examine the effects of straw return (S₀: 0, S₁: 7 t ha⁻¹) and nitrogen fertilization (N₀: 0, N₁: 150, N₂: 250, and N₃: 350 kg ha⁻¹) on bulk density (BD), aggregate distribution, nutrient dynamics, and rice yield. Results: Straw return to the field promoted the transformation of aggregates into larger ones, resulting in increased aggregate stability. Additionally, it significantly reduced the BD by 8.5 to 10% and increased the soil organic carbon (SOC), nitrogen (N), phosphorus (P), and potassium (K) content of the aggregates. The 0.25–2 mm aggregates were found to be the major contributors to fertility enhancement. There were no significant differences in the structure of the aggregates and the nutrient levels between the N₂ and N₃ treatments. Straw return led to a significant increase in rice yield by 20.90 to 27.57%. However, the differences between the S₁N₂ and S₁N₃ treatments were not significant, indicating that S₁N₂ had better benefits. Regression analysis revealed that the optimum nitrogen application rate tended to decrease with the increase in years of straw return. Conclusion: The incorporation of straw and optimal nitrogen (quantity) into saline sodic soils can enhance soil structure and aggregate nutrients, particularly in 0.25–2 mm aggregates. This agronomic measure is viable in improving soil productivity which ultimately increases rice yield. [ABSTRACT FROM AUTHOR]