[Meta-analysis on the Effects of Organic Fertilizer Application on Global Greenhouse Gas Emissions from Agricultural Soils].

Abstract

To explore the direct and indirect effects of organic fertilizer application on greenhouse gas emissions from agricultural soils, a total of 1228 groups of data from 129 published studies were selected. Meta-analysis was used to analyze the effects of organic fertilizer on global greenhouse gas emissions from agricultural soils and their influencing factors. Meanwhile, a structural equation model （SEM） was further constructed to quantify and determine the causal relationships between the factors. The results showed that, overall, compared with those under no fertilization, organic fertilizer substitution increased CO₂ emissions by 70.73% （lnR： 0.53, 95%CI： 0.45-0.62）, CH₄ emissions by 52.58% （lnR： 0.42, 95%CI： 0.26-0.59）, and N₂O emissions by 208.14% （lnR： 1.13, 95%CI： 1.04-1.21）, respectively. Compared with those under the application of inorganic fertilizers, the substitution of organic fertilizers increased CO₂ emissions by 19.24% （lnR： 0.18, 95%CI： 0.13-0.22）, CH₄ emissions by 27.72% （lnR： 0.24, 95%CI： 0.15-0.34）, and N₂O emissions by -3.66% （lnR：-0.04, 95%CI：-0.11- 0.04）. Under the application of organic fertilizer, the dryland system had the greatest impact on both CO₂ and N₂O emissions, and the rice system had the most significant effect on CH₄ emission effects. The average CO₂ growth rate was highest in silty soils, and sandy soils had a greater effect on the average growth rates of N₂O and CH₄. The average growth rate of CO₂ and N₂O was extremely large under straw substitution compared to that under commercial organic fertilizer and biogas. The substitution of farmyard manure had significant CH₄ emissions from soil promotion. Greenhouse gas emissions were significantly increased under the nitrogen fertilizer and organic fertilizer treatments. The SEM showed that mean annual temperature （MAT） was the most important environmental determinant of CO₂ and N₂O emissions, in which soil CO₂ emissions were significantly positively correlated with MAT （P < 0.01） and soil N₂O emissions were negatively correlated with MAT. The main environmental determinants of CH₄ emissions in dryland, grassland, and rice systems were annual precipitation （MAP） and mean annual temperature （MAT）, respectively, which were both significantly and positively correlated with each other （P < 0.05）. This research can provide a scientific basis for optimizing fertilizer management and mitigating greenhouse gas emissions from farmland.