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Title: Great Plains climate and land-use effects on soil organic carbon

Author
item FOLLETT, RONALD - Retired ARS Employee
item Stewart, Catherine
item Pruessner, Elizabeth
item KIMBLE, JOHN - Retired Non ARS Employee

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/16/2014
Publication Date: 1/13/2015
Publication URL: http://doi: 10.1111/gcbb.12142
Citation: Follett, R.F., Stewart, C.E., Pruessner, E.G., Kimble, J. 2015. Great Plains climate and land-use effects on soil organic carbon. Soil Science Society of America Journal. 79:261-271.

Interpretive Summary: Soil organic carbon (SOC) is essential to agricultural productivity and sustainability in response to climate and land-use change. We examined 14 sites across the US Great Plains to determine the sensitivity of important SOC fractions to climatic gradients (temperature and precipitation) and land-use change (native, CRP, and cropped). We measured particulate organic matter (POM-C) and soil mineral associated (Cmin-C) C, soil microbial biomass C (SMB-C) and soil aggregate stability (%Agg Stab). The Cmin-C fraction comprised the majority of total SOC (70%) and also comprised most of the whole soil response to temperature and moisture gradients. The POM-C fraction could be used as an easily measured indicator of land-use impacts in soil, since POM-C and SMB-C were highly correlated. Conservation practices that promote soil aggregation and reduce disturbance and erosion will be critical in maintaining mineral soil C and ameliorating soil C loss though increased temperatures. These practices have additional benefit of building the POM-C fraction and SMB-C.

Technical Abstract: Soil organic carbon (SOC) is essential to agricultural productivity and sustainability in response to climate and land-use change. Here, we examine 14 sites across the US Great Plains to determine the sensitivity of important SOC fractions to climatic gradients (temperature and precipitation) and land-use change (native, CRP, and cropped). We measured particulate organic matter (POM-C) and soil mineral associated (Cmin-C) C, soil microbial biomass C (SMB-C) and soil aggregate stability (%Agg Stab). All fractions (POM-C, SMB-C and % Agg Stab) except Cmin were affected by land-use, and decreased from native>CRP>cropped sites. Total soil C and all the fractions decreased with increasing temperature and increased with greater clay content. Surprisingly, only the mineral-associated C (Cmin-C and %AggStab) increased with increasing MAP:ET ratio, the more labile fractions POM-C, SMB-C did not. Despite greater %AggStab, there was not POM protection, suggesting that aggregate turnover and subsequent C loss was greater in sites with more moisture. The Cmin-C fraction comprised the majority of total SOC (70%) and also comprised most of the whole soil response to temperature and moisture gradients. The POM-C fraction could be used as an easily measured indicator of land-use impacts in soil, since POM-C and SMB-C were highly correlated. Conservation practices that promote soil aggregation and reduce disturbance and erosion will be critical in maintaining mineral soil C and ameliorating soil C loss though increased temperatures. These practices have additional benefit of building the POM-C fraction and SMB-C.