The Impact of Applying Chicken Manure on Nutrient Release From Wheat Straw and the Evolution of Dissolved Organic Matter in Soil

Returning crop straw to the field with livestock manure is an important technique for comprehensively utilizing solid waste resources. Exogenous organic matter returning primarily involves infiltrating dissolved organic matter (DOM) into the soil. Investigating the evolution characteristics of DOM can effectively predict the turnover of unstable carbon pools. However, the evolution patterns of soil DOM when combining straw returning with adding chicken manure are still unclear. This study conducted a field trial during the maize growth period in the North China Plain, with four treatments: wheat straw returning, wheat straw combined with chicken manure application, chicken manure returning, and no fertilizer application. Using three-dimensional fluorescence spectroscopy combined with parallel factor analysis, the temporal evolution of DOM content and composition during wheat straw returning was elucidated, and the influence of DOM composition evolution on straw decomposition was investigated. The results showed that adding chicken manure significantly increased the straw mass loss rate, carbon and nitrogen release rates, soil microbial carbon, and microbial nitrogen by 4.25%, 5.56%, 1.56%, 12.44%, and 56.98%, respectively. The humification index of soil DOM increased significantly by 11.97%. Variance decomposition analysis revealed that the combination of humic-like and protein-like substances positively impacted microbial carbon and nitrogen. The combination of humic substances and protein substances, as well as microbial activity, had a positive impact on straw carbon release. Humic-like substances and microbial biomass carbon positively affected straw nitrogen release. In summary, the supplementation of chicken manure has demonstrated a remarkable enhancement in the efficacy of straw incorporation, as evidenced by the notable augmentation in soil microbial biomass and expedited processing of labile carbon pools. Consequently, this synergistic effect facilitates a more efficient turnover of soil nutrients while effectively mitigating any potential environmental hazards attributed to straw residue. The findings contribute significantly to our comprehension of the turnover dynamics of labile carbon pools in soil after adding external organic materials. Moreover, the study furnishes a solid theoretical framework and empirical evidence to support the optimization of wheat straw incorporation through the application of chicken manure.