Effect of Nitrogen and Maize Straw on Soil Nitrogen Transformation, Farm Profitability, and Wheat Yield: Balancing Productivity and Environmental Sustainability

Abstract

Mitigating nitrogen (N) losses, particularly nitrous oxide (N₂O) emissions from excessive sole-N fertilizer use, is critical for environmental and agronomic sustainability. This two-year study evaluates the effects of integrating maize straw (MS) with N fertilizer on N transformation, wheat yield, and farm profitability while assessing all N₂O emission sources to refine global estimates. Higher N (160 kg ha⁻¹) and MS (9 t ha⁻¹) rates enhanced nitrification and denitrification due to increased microbial activity, improving nitrate (NO₃⁻) availability but also increasing N₂O emissions. These emissions peaked at 124 days after sowing (DAS) in both years. However, integrating N and MS reduced N losses in the second year. The study provides insights into plant-mediated N₂O emissions, demonstrating minimal reliance on external inputs using the plant-cutting method. Correlation and principal component analysis highlight integrated N and MS management as crucial for improving productivity, reducing N₂O emissions, and enhancing soil health. Economic analysis confirms that combining N and MS significantly increases wheat profitability, with all treatments achieving a value-cost ratio > 2. Balanced fertilization (120 kg N ha⁻¹ and 6 t MS ha⁻¹) optimizes yield, reduces environmental impacts, and sustains soil health long-term.