Effects of white-rot fungal pretreatment of corn straw return on greenhouse gas emissions from the North China Plain soil

Straw-return with fungal treatment is a potential method for reducing soil greenhouse gas emissions through carbon (C) sequestration and N2O mitigation. However, there is little information on the effects of different fungal treatments of crop straw return on soil CO2 and N2O emissions. To explore to what extent decomposed corn straw and its components controls soil CO2 and N2O emissions, we set up three sequential incubation experiments using soil collected from the North China Plain, an intensive agricultural area. Interactions between the different C contents of corn straw (CS), CS pretreated with Irpex lacteus (ICS), CS pretreated with Phanerochaete chrysosporium (PCS) and different NO3--N concentrations on the effect of soil CO2 and N2O emissions were conducted, and the kinetics of CO2 and N2O as influenced by changes in soil biochemical factors were analyzed. The effects of different lignocellulose components (lignin, cellulose, and xylan) on soil CO2 and N2O emissions were further studied. The results showed that straw pretreatment did not affect CO2 emissions. Both CO2 and N2O emissions increased when the C and N contents increased. However, applying PCS to 70% water-filled pore space soil effectively decreased the soil N2O emissions, by 41.8%-76.3% compared with adding the same level of CS. Moreover, extracellular enzyme activities related to C and N cycling were triggered, and the nosZI and nosZII abundances were significantly stimulated by the PCS application. These effects are closely related to the initial soluble C content of this treatment. Furthermore, adding xylan can significantly reduce N2O emissions. Overall, our data suggest that the environmentally beneficial effects of returning straw can be greatly enhanced by applying the straw-degrading white-rot fungi of P. chrysosporium in the North China Plain soil. Future studies are needed in the field to upscale this technology.