Abstract

Agricultural fertilizer management significantly influences both soil organic carbon (SOC) sequestration and greenhouse gas (GHG) emissions, yet their interdependent relationships remain poorly quantified across different management regimes. This study investigated the linkages between SOC stocks and GHG emissions (CO₂, CH₄, N₂O) under varying fertilizer management practices across 36 long-term experimental sites in temperate agricultural systems. Fertilizer treatments included: organic manure (30 t ha⁻¹), synthetic NPK (150-60-40 kg ha⁻¹), integrated nutrient management (INM), and unfertilized control over a 15-year period. Results demonstrated strong negative correlations between SOC stocks and net GHG emissions, with organic manure systems achieving 45% higher SOC content (28.4±3.2 g kg⁻¹) while reducing net GHG emissions by 35% compared to synthetic fertilizers. Integrated nutrient management optimized this relationship, maintaining SOC levels 25% above synthetic treatments while achieving the lowest net global warming potential (2.8±0.4 t CO₂-eq ha⁻¹ yr⁻¹). N₂O emissions showed exponential relationships with nitrogen application rates, increasing from 1.2 kg N₂O-N ha⁻¹ yr⁻¹ in control plots to 8.7 kg N₂O-N ha⁻¹ yr⁻¹ under high synthetic N rates. Soil respiration rates were 15-20% lower in high-SOC systems due to enhanced carbon stabilization and improved soil structure [10]. Economic analysis revealed that INM systems provided net climate benefits of $385-520 ha⁻¹ yr⁻¹ when carbon credits and reduced GHG penalties were considered. These findings demonstrate that strategic fertilizer management can simultaneously enhance soil carbon storage and mitigate agricultural GHG emissions, providing dual climate benefits essential for sustainable intensification of agricultural systems.