Soil Quality Responses to Contrasting Management: Observations from Long-Term Trials in Central North Dakota.

There is a need for comprehensive soil quality evaluations of conservation management practices.  A study was conducted in spring 2014 to evaluate soil quality in contrasting long-term treatments at the USDA-ARS Northern Great Plains Research Laboratory.  Evaluations compared ‘business as usual’ management practices with land management systems characterized by one or more principles of conservation agriculture (e.g., increased crop diversity, livestock integration, continuous soil cover, etc.).  Our goal was to determine the contribution of each principle of conservation agriculture to soil quality according to three approaches.  Each paired contrast was conducted on similar landscapes and soil types, and included a comparison of soil physical, chemical, and microbiological properties and processes.  The geometric mean of several enzyme activities was calculated to provide an index of the soil biogeochemical potential.  Additionally, select measurements were incorporated into the Soil Management Assessment Framework (SMAF) to provide an integrative assessment of soil quality.  Incorporation of soil-based outcomes with relevant production and economic metrics allowed for quantification of tradeoffs between contrasting management practices.