Mineralization of organic carbon and formation of microbial biomass in soil: effects of clay content and composition and the mechanisms involved

Rakhsh, Fatemeh, Golchin, Ahmad, Agha, Ali Beheshti Al, and Nelson, Paul N. (2020) Mineralization of organic carbon and formation of microbial biomass in soil: effects of clay content and composition and the mechanisms involved. Soil Biology and Biochemistry, 151. 108036.

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Abstract

Mineralization of soil organic carbon and CO2 emission from the soil is slowed by interactions between organic matter and minerals. The main minerals involved are clay minerals and oxides but there is limited understanding of their effects when combined, as occurs in soil. We aimed to determine the effects of clay content and composition on organic carbon stabilization in soil, and the mechanisms involved. This was achieved by studying the decomposition of alfalfa residues in artificial soils made from quartz sand and kaolinite with and without additions of the non-layered colloids (NLCs) goethite, manganese oxide or imogolite. The artificial soils were inoculated with microbes from natural soil and incubated at 23 °C in the dark at 60% of water holding capacity for 180 days. With increasing contents of clay and NLCs, organic carbon mineralization decreased, whereas carbohydrate and microbial biomass carbon contents increased. Of the NLCs, goethite had the least effect and imogolite the greatest effect on carbohydrate content. The effects of the treatments on mineralization and carbohydrate content were explained mostly by specific surface area (> 83% of variation), presumably due to the effects on sorption. The effects of the treatments on microbial biomass were related to the volume of habitat (water-filled pore space) and availability of substrate (influenced by sorption). These results showed that clay content and composition influenced the stabilization of soil organic carbon mostly through the supply of surfaces for sorption reactions rather than via interactions unique to particular colloids.

Item ID: 64621
Item Type: Article (Research - C1)
ISSN: 1879-3428
Keywords: biomass carbon, carbohydrate, cation exchange capacity, oxyhydroxides, specific surface area, water holding capacity
Copyright Information: © 2020 Elsevier Ltd. All rights reserved.
Date Deposited: 18 Oct 2020 21:32
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0503 Soil Sciences > 050301 Carbon Sequestration Science @ 30%
05 ENVIRONMENTAL SCIENCES > 0503 Soil Sciences > 050303 Soil Biology @ 40%
05 ENVIRONMENTAL SCIENCES > 0503 Soil Sciences > 050304 Soil Chemistry (excl Carbon Sequestration Science) @ 30%
SEO Codes: 82 PLANT PRODUCTION AND PLANT PRIMARY PRODUCTS > 8298 Environmentally Sustainable Plant Production > 829802 Management of Greenhouse Gas Emissions from Plant Production @ 40%
96 ENVIRONMENT > 9614 Soils > 961402 Farmland, Arable Cropland and Permanent Cropland Soils @ 40%
96 ENVIRONMENT > 9609 Land and Water Management > 960904 Farmland, Arable Cropland and Permanent Cropland Land Management @ 20%
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