Implication of O(2) dynamics for both N(2)O and CH(4) emissions from soil during biological soil disinfestation

Soil O(2) dynamics have significant influences on greenhouse gas emissions during soil management practice. In this study, we deployed O(2)-specific planar optodes to visualize spatiotemporal distribution of O(2) in soils treated with biological soil disinfestation (BSD). This study aimed to reveal the role of anoxia development on emissions of N(2)O and CH(4) from soil amended with crop residues during BSD period. The incorporation of crop residues includes wheat straw only, wheat straw with biochar and early straw incorporation. The anoxia in soil developed very fast within 3 days, while the O(2) in headspace decreased much slower and it became anaerobic after 5 days, which was significantly affected by straw and biochar additions. The N(2)O emissions were positively correlated with soil hypoxic fraction. The CH(4) emissions were not significant until the anoxia dominated in both soil and headspace. The co-application of biochar with straw delayed the anoxia development and extended the hypoxic area in soil, resulting in lower emissions of N(2)O and CH(4). Those results highlight that the soil O(2) dynamic was the key variable triggering the N(2)O and CH(4) productions. Therefore, detailed information of soil O(2) availability could be highly beneficial for optimizing the strategies of organic amendments incorporation in the BSD technique.