Probing deep to express root-zone enrichment of soil-test biological activity on southeastern U.S. farms

Soil organic carbon (C) and nitrogen (N) accumulation contributes to improved soil health condition, particularly after a history of tillage-intensive land use. Soil-test biological activity (STBA) is an active fraction of organic matter that is responsive to conservation management. This essay summarizes the need, concept, and method of calculating root-zone enrichment of STBA and other organic C and N fractions on private farms. Calculation of root-zone enrichment separates the pedogenic influence on organic matter content from that of contemporary management. This separation is particularly important when attempting to determine STBA or soil organic C stock change in response to management across variable landscapes. Reasonable farm-level estimates of STBA and stocks of soil organic C and N can be obtained from one to two dozen sampling sites on farms with differences in land use, a process that could help propel in-depth assessments of soil health condition and C stock change.