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

Authors: Franzluebbers, Alan

Submitted to: Agricultural & Environmental Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/11/2022
Publication Date: 8/9/2022
Citation: Franzluebbers, A.J. 2022. Probing deep to express root-zone enrichment of soil-test biological activity on southeastern U.S. farms. Agricultural and Environmental Letters. 7:e20087. https://doi.org/10.1002/ael2.20087.
DOI: https://doi.org/10.1002/ael2.20087

Interpretive Summary: Soil organic matter accumulation contributes to improved soil health condition, particularly after a history of degradative land use. Soil-test biological activity characterizes soil microbial activity and is an active fraction of organic matter that is responsive to conservation management. This essay was prepared by a USDA scientist in Raleigh NC to summarize the need, concept, and method of calculating root-zone enrichment of soil-test biological activity on private farms. Calculation of root-zone enrichment separates the influence of historical soil formation processes on organic matter fractions from that of contemporary management. This separation is particularly important when attempting to determine soil-test biological activity or soil organic carbon change in response to management across variable landscapes. It is suggested that reasonable farm-level estimates of soil-test biological activity and contents of soil organic carbon and nitrogen can be obtained with one to two dozen sampling sites on farms with a few differences in land use, a process that could help propel in-depth assessments of soil health condition and carbon sequestration.

Technical Abstract: 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.