The Impact of Organic Amendments on Carbon Dynamics and the Soil Microbial Community

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The Ohio State University

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The degradation of agricultural soils contributes significantly to CO2 emissions and threatens both global food security and ecosystem function. Soil microorganisms drive these biological functions and the formation of soil properties that contribute to both carbon sequestration and promotion of plant growth. Soil organic amendments can prevent or mitigate soil degradation by enhancing soil carbon, but the effect on soil microbial community structure is lacks a clear consensus. This field study investigated microbial CO2 respiration, total soil carbon content, and soil microbial community composition in plots with 30 years of application of three common organic amendments: cover crop, manure, and compost. Respiration was unaffected by treatments. Soil carbon was enhanced by compost and manure treatments in comparison to the control. Analysis of microbial ester-linked fatty acids revealed the microbial community composition of the cover crop treatment to be highly similar to that of the control. The manure and compost treatments were also similar to each other in overall community composition, including having higher microbial biomass compared to the cover crop treatment and control. Data suggested that the differences in community composition are likely a result of differences in carbon availability of different amendments. Manure and compost amendments are recommended to maximize carbon sequestration and soil microbial biomass.



soil science, microbiology, carbon sequestration, organic amendments, agriculture, climate change