|NUNES, MARCIO - Orise Fellow|
|KARLEN, DOUGLAS - Retired ARS Employee|
Submitted to: Environmental and Sustainability Indicators
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/24/2020
Publication Date: 9/28/2020
Citation: Nunes, M.R., Karlen, D.L., Veum, K.S., Moorman, T.B. 2020. A SMAF assessment of U.S. tillage and crop management strategies. Environmental and Sustainability Indicators. 8. Article 100072. https://doi.org/10.1016/j.indic.2020.100072.
Interpretive Summary: The Soil Management Assessment Framework (SMAF) has been used for soil health assessments. However, the sensitivity of the SMAF scoring curves to detect soil health changes induced by management are still unknown. Although the sensitivity and efficacy of SMAF scoring curves for detecting agronomic management effects on soil function were verified, some algorithms (especially for soil organic C and beta-glucosidase) are underestimating scores in some US regions. This large-scale analysis also confirmed the benefits of conservation practices to enhance soil health, especially biological and physical soil functions. These results are useful for consultants and researchers, but results indicate that further evaluation of the SMAF scoring curves is merited.
Technical Abstract: Tillage and crop management evolved as agricultural cornerstones because of their roles in creating seedbeds, cycling nutrients, and controlling weeds. Unintended consequences, however, included oxidation of soil organic matter, insufficient surface soil cover, increased runoff as well as wind and water erosion that gradually degraded many soil resources. Within the past two decades, the concept of soil health has emerged with an emphasis on mitigating soil degradation induced by long-term agriculture. Our hypotheses are that:(1) reducing tillage intensity and increasing cropping system diversity will help restore soil health by improving critical soil functions, and (2) those changes can be quantified using the Soil Management Assessment Framework (SMAF). To test our hypotheses, a large dataset was compiled from research throughout the U.S. and used as input for a SMAF analysis. Indicator scores for soil organic carbon (SOC), microbial biomass C (MBC), beta-glucosidase activity (BG), macroaggregate stability (AS), bulk density (BD), soil pH, soil P and K, and an overall soil quality index (SQI) were computed. Measured, scored, and SQI values were used to evaluate tillage intensity [conventional (CT), reduced tillage (RT), no-till (NT), and perennial systems (PER)] and system diversification [annual cropping system without cover crops (ANCC) and with cover crops (ACC), and perennial systems (PER)] effects. Reducing tillage intensity and increasing diversity increased topsoil (=15-cm) SOC, MBC, BG, and AS values. The SMAF scoring curves discriminated among and were sensitive to agronomic practices affecting soil function. The highest SQI values were associated with PER systems because of improved soil biological and physical functions. Overall, this national assessment confirmed the utility of the SMAF and highlighted the benefits of conservation practices.