What factors influence the dynamics of mineralization and humification processes of organic amendments in soil?

Increasing attention is being directed toward carbon sequestration in agricultural soils due to its potential to mitigate global climate change. Enhancing soil organic carbon (SOC) storage is not only vital for addressing climate concerns but also essential for soil health, agricultural productivity, and, ultimately, food security. Organic amendments—such as biogas digestate, compost, manure, and slurry—have proven effective in increasing SOC levels. However, the decomposition dynamics of various exogenous organic amendments in soil vary significantly due to their distinct physicochemical properties, resulting in different mineralization and humification pathways driven by diverse microbial metabolic processes. Given these complexities, a comprehensive investigation into the mineralization and humification dynamics of organic amendments is crucial for accurately assessing their carbon sequestration potential in soil matrices and for optimizing strategies to enhance soil carbon storage.

In this study, the authors investigated the mineralization, humification characteristics, and dynamics of microbial communities of two organic materials, including chicken manure (CM) and composted kitchen waste compost (KW) in farmland soil by conducting nylon mesh bag in-situ incubation experiments combined with indoor analysis and high-throughput microbial sequencing technology. The results showed that the organic amendments exhibited similar patterns of mass loss, with over 43.95 % of mass loss occurring in the early stage of decomposition (days 1–56), and CM and KW decomposition rates stabilizing in the later stage (days 56–280). The study also found that although the precursors and levels of humus of CM and KW differed, they all enhanced the humification process, significantly affecting the retention of carbon and nitrogen during incubation. At 280 days, carbon and nitrogen residues were more in CM than in KW. Additionally, the study demonstrated that the stoichiometric characteristics and complexity of microbial communities, as well as the distribution of specific bacterial and fungal phyla had a significant impact on the mineralization and humification processes of organic materials.

These findings will enhance understanding of organic amendments decomposition in soils and provide valuable references for soil carbon sequestration with organic inputs.

This study was published in the Journal of Frontiers of Agricultural Science and Engineering in 2024, 11(4) 

DOI: 10.15302/J-FASE-2024546.