Soil-test biological activity with the flush of CO2: VIII. Soil type and management diversity

Authors: Franzluebbers, Alan; PERSHING, MOLLY - Skagit Farmers Supply

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/13/2020
Publication Date: 11/18/2020
Citation: Franzluebbers, A.J., Pershing, M. 2020. Soil-test biological activity with the flush of CO2: VIII. Soil type and management diversity. Soil Science Society of America Journal. 84:1658-1674.

Interpretive Summary: The supply of nitrogen to agricultural crops and forages can be partially achieved from mineralization of nitrogen from soil organic matter. A biologically based soil testing tool has been developed for making predictions of soil organic nitrogen mineralization, but needs to be tested under a diversity of climates, land uses, and soil conditions. A scientist from USDA-Agricultural Research Service in Raleigh NC collaborated with a former graduate student at North Carolina State University to evaluate how soil-test biological activity determined from the flush of CO2 following rewetting of dried soil relates to several dozen other soil properties. Soil-test biological activity was most closely related with other soil organic carbon and nitrogen fractions, like cumulative carbon mineralization during 24 days, basal soil respiration, particulate organic carbon, and nitrogen mineralization. Soil-test biological activity and nitrogen mineralization were closely associated across all samples, but diverged somewhat between prairie soils and Blue Ridge, Piedmont, Ridge/Valley, and Coastal Plain soils of the eastern US. Difference in land use between cropland and pastureland did not alter this association. Soil-test biological activity was verified as a robust indicator of soil organic nitrogen supply, as well as of general soil biological condition to assess soil decomposition potential and potential soil carbon storage.

Technical Abstract: Soil-test biological activity is proposed as a key indicator to describe the function of soil to catabolize organic amendments, promote soil organic C sequestration, and cycle nutrients. We explored how climatic zone, land use, and physiographic region might affect the relationship of soil-test biological activity to a wide swath of soil fertility properties and processes. Soils from eastern states of Georgia, North Carolina, Pennsylvania, and Virginia were Aquults, Fluvents, Udalfs, Udepts, and Udults and soils from western states of Nebraska and Oklahoma were Udolls and Ustolls. Land use comparison was between annual cropland and perennial pasture. Prairie region had silt loam and silty clay loam soils, Ridge/Valley region had silt loam soil, Piedmont region had fine sandy loam, loam, silt loam, sandy clay loam, and sandy loam soils, and Coastal Plain region had fine sandy loam, loam, sandy clay loam, and sandy loam soils. Across land cover and locations, soil-test biological activity was most strongly associated with cumulative C mineralization, basal soil respiration, particulate organic C, net N mineralization, residual soil ammonium, soil microbial biomass C, and total soil N. Climatic zone modified the association between soil-test biological activity and net N mineralization, possibly due to greater N immobilization in more arid soils. Physiographic region had variable effects on the relationship between soil-test biological activity and net N mineralization. Difference in land use did not alter this relationship significantly. Soil-test biological activity was verified as a robust indicator of soil organic N supply, as well as of general soil biological condition to assess soil catabolic potential and potential C storage.