Effects of poly-gamma-glutamic acid on soil nitrogen and carbon leaching and CO2 fluxes in a sandy clay loam soil

摘要

Poly-gamma-glutamic acid (gamma-PGA) has shown a significant promotional effect on plant production. However, little is known of the environmental footprint generated from the application of gamma-PGA. A laboratory trial was conducted to study the effects of gamma-PGA on soil nitrogen and carbon leaching loss and carbon dioxide (CO2) emission by applying 0, 0.0125, 0.025, 0.05, 0.1, 0.2, 0.4, and 0.8 g gamma-PGA kg(-1) soil to soil receiving 150 kg N ha(-1) in the form of urea. Results showed that the cumulative loss of ammonium and nitrate decreased by 17.81%-29.31% and 8.27%-52.42% when the application rate of gamma-PGA reached 0.1 g kg(-1) soil. Cumulative total dissolved nitrogen loss was diminished by 7.16%-40.10% when the gamma-PGA application rate was 0.2-0.8 g kg(-1) soil. Cumulative loss of dissolved organic carbon was rarely affected by the gamma-PGA, whereas cumulative CO2 flux was notably enhanced by 26.87%-180.70%. Soil total nitrogen (TN) and soil organic carbon (SOC) contents varied with the different application rates of gamma-PGA; soil TN increased by 6.34%-8.04%, and SOC remained unchanged only when the gamma-PGA application rate was 0.4-0.8 g kg(-1) soil. In conclusion, before considering using gamma-PGA in an agroecosystem, its effects on both the environment and plant production should be examined.