Plant microbial interactive effects on soil carbon in relation to soil structure

Abstract

The plant input of organic carbon (C) into soil is essential for the soil structure, including the formation of soil aggregates. The inclusion of C in soil aggregates ensures protection from microbial decomposers that can move C from the soil -as a C sink- to the atmosphere through CO2 emissions, thereby raising the concentration of atmospheric greenhouse gases. The plant C sequestration in soil aggregates and its stability in the long-term is dependent on the microbial processes that vary widely according to the soil, climate, plant C quality, and soil microbial communities. The exact mechanisms of the microbial decomposition of plant substrates and role of soil microbes (like bacteria and fungi) in the formation and stability of soil aggregates is still unknown. Plant rhizodeposits in the soil can influence the soil microbial activity. In this thesis, the factors affecting the soil aggregate formation, the microbial decomposition of plant residue added to the soil, and the plant-microbial interactive effects on the decomposition of added litter to soil, soil structure, and soil C content were explored. Longer studies are needed to investigate the effects of plant residue soil amendments and rhizosphere on soil aggregation and soil C. Nevertheless, plant residue inputs to the soil should be always considered by farmers and growers to retain depleted nutrients from the soil such as C, despite the inconsistent magnitude of benefits to soil C and aggregation among different residue origins.