Greenhouse gas emissions from cassava production influenced by 47 years of diverse fertilizer application practices in Thailand: insights from two years of measurements

Greenhouse gas (GHG) emissions and their mitigation in food crop production, particularly in tropical regions such as Thailand, remain a knowledge gap in advancing sustainable agricultural systems. This study used a 47-year field experiment to assess the effects of diverse fertilizer application practices on GHG emissions, soil properties and cassava yield. The results revealed that carbon inputs from crop residues (CR) and compost (CP) significantly elevated carbon dioxide emissions, primarily due to enhanced soil microbial respiration. Nitrogen applications, whether from mineral or organic sources, significantly stimulated nitrous oxide (N2O) emissions, with greater N inputs leading to higher N2O releases. At equivalent N application rates, mineral N fertilizers induced greater N2O emissions, having a mean emission factor (EF) of 0.75% compared to CR-derived N with an EF of 0.56%. Additionally, mineral fertilizers led to soil acidification and nutrient accumulation. CR and CP inputs increased soil organic carbon stocks by 42.1% and 53.3%, respectively, relative to the control. CP addition also improved soil pH and significantly enhanced phosphorus and potassium availability. Notably, the combined inputs of NPK fertilizers and CR achieved the lowest GHG emissions per unit yield, highlighting the potential of integrated fertilizer application strategies to mitigate GHG emissions while sustaining crop productivity.