Smucker, A.J.M., E.J. Park, R. Horn, and E. Jasinska
Presented at the All Scientist Meeting (2004-10-08 )
Soil aggregates are the primary reservoirs of carbon © in the soil. Greater quantities of C, from root and plant exudates and decomposing plant residues accumulate at aggregate surfaces and can be moved into aggregate interiors by repeated wetting and drying cycles. As intra-aggregate pore networks increase and more C moves inward, aggregates become more stable. These feed back mechanisms increase internal sequestration of soil C. Accumulations of C and N compounds on aggregate surfaces increase hydrophobic properties at aggregates. Respiration rates by whole intact aggregates from CT treatments were nearly 2-fold greater than soils from exterior regions of aggregates from Forest and NT whole aggregates. In contrast, respiration rates by soils from interior regions of CT aggregates were 70% of NT interiors. These flux rates and subsequent biogeochemical processes influence different microbial populations at surfaces and within aggregates. Management practices that promote these processes could dramatically increase both the strengths of aggregates and the rates of C deposition and retention.
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