Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 21, 2014
Publication Date: September 1, 2014
Citation: Karlen, D.L., Stott, D.E., Cambardella, C.A., Kremer, R.J., King, K.W., McCarty, G.W. 2014. Surface soil quality in five midwestern cropland Conservation Effects Assessment Project watersheds. Journal of Soil and Water Conservation. 69(5):393-401. Interpretive Summary: Soil quality assessment was suggested by the National Academy of Sciences as being an important piece of information for assessing the effetiveness of conservation program investments by the USDA Natural Resources Conservation Service (NRCS). To help develop guidelines for watershed-scale soil quality assessment, the Agricultural Research Service (ARS) conducted a soil quality assessment within five Midwestern cropland Conservation Effects Assessment Program (CEAP) research sites. We found that soil quality could be assessed and that according to the Soil Management Assessment Framework (SMAF) soils in these watersheds were functioning at between 70 and 90 percent of their potential for crop production. We recommend working with soil testing laboratories and crop consultants to incorporate similar soil quality assessments into routine evaluations of various conservation practices. This information will be important for the NRCS, researchers, and persons interested in conservation of our soil and water resources.
Technical Abstract: Soil quality assessment is a proactive process for evaluating long-term effects of soil and crop management practices on biological, chemical, and physical indicators of soil health. Our objective was to determine if any of three conservation practices (manure application, crop rotation, or no-tillage) significantly affected selected soil quality indicators or various indices within five ARS cropland Conservation Effects Assessment Project (CEAP) watersheds located in the U.S. Corn/Soybean Belt. Ten soil quality indicators reflecting physical [bulk density (BD) and water-stable macro-aggregates (WSA)], chemical [pH, electrical conductivity (EC), soil-test phosphorus (P), and soil-test potassium (K)], and biological [soil organic carbon (SOC), potentially mineralizable nitrogen (PMN), microbial biomass carbon (MBC), and ß-glucosidase (BG)] properties or processes were measured within 600, 0 to 5-cm and 398, 5 to 15-cm depth increment samples, evaluated statistically and scored using the Soil Management Assessment Framework (SMAF). Watershed, manure application, tillage, and cropping systems effects were detectable through both measured and SMAF scored indicator values. We conclude that monitoring soil quality at the watershed scale is feasible and suggest that such assessments (i.e., every three to five years) could be efficiently incorporated into existing conservation programs by interfacing with soil testing and crop consulting groups.