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

Mitigation of soil N2O emissions by decomposed straw based on changes in dissolved organic matter and denitrifying bacteria

The return of decomposed straw represents a less explored potential option for reducing N2O emissions. However, the mechanisms underlying the effects of decomposed straw return on soil N2O mitigation are still not fully clear. Therefore, we used a helium atmosphere robotized continuous flow incubation system to compare the soil N2O and N2 emissions from four treatments: CK (control: no straw), WS (wheat straw), IWS (wheat straw decomposed with Irpex lacteus), and PWS (wheat straw decomposed with Phanerochaete chrysosporium). All the treatments have been fertilized with the same amount of KNO3. Furthermore, we also analyzed i) the chemodiversity of soil dissolved organic matter (DOM), ii) the nirS, nirK, and nosZ gene copies and relative abundances of denitrifying bacterial communities (DBCs), and iii) the specific linkages between N2O emissions and DOM and DBC. The results showed that the WS, IWS and PWS treatments increased N2O emissions compared to the CK treatment. However, applying decomposed straw to soil, especially straw treated with P. chrysosporium, effectively decreased the soil N2O and increased N2 emissions compared to WS and IWS. Moreover, the IWS and PWS treatments increased the CHO composition, but they decreased the CHON and CHOS compositions of heteroatomic compounds of DOM compared with the WS and CK treatments. Furthermore, the WS, IWS and PWS treatments all significantly increased the nirS and nosZ gene copies compared with the CK treatment. Additionally, compared with the other treatments, the PWS treatment significantly shaped the DBC and led to a higher relative abundance of Pseudomonas with nirS and nosZ genes. Meanwhile, Network analysis showed that the mitigation of N2O was closely related to particular DOM molecules, and specific DBC taxa. These results highlight the potential for decomposed straw amendments to mitigate of soil N2O emissions not only by changing soil DOM but also mediating the soil DBC.

Microbial-Mediated Emissions of Greenhouse Gas from Farmland Soils: A Review

The greenhouse effect is one of the concerning environmental problems. Farmland soil is an important source of greenhouse gases (GHG), which is characterized by the wide range of ways to produce GHG, multiple influencing factors and complex regulatory measures. Therefore, reducing GHG emissions from farmland soil is a hot topic for relevant researchers. This review systematically expounds on the main pathways of soil CO2, CH4 and N2O; analyzes the effects of soil temperature, moisture, organic matter and pH on various GHG emissions from soil; and focuses on the microbial mechanisms of soil GHG emissions under soil remediation modes, such as biochar addition, organic fertilizer addition, straw return and microalgal biofertilizer application. Finally, the problems and environmental benefits of various soil remediation modes are discussed. This paper points out the important role of microalgae biofertilizer in the GHG emissions reduction in farmland soil, which provides theoretical support for realizing the goal of “carbon peaking and carbon neutrality” in agriculture.