Soil Quality Outcomes from Dryland Cropping Systems: Comparison of Conservation and Business As Usual Practices.

Increased emphasis has been placed on developing conservation management practices that are inherently resilient to external stressors, yet are highly productive, profitable, and enhance ecosystem health. This emphasis has underscored the critical role of soil to affect agricultural and environmental outcomes through impacts on ecosystem services. The objective of this study was to determine effects of conservation management practices on soil quality for dryland cropping systems in a semiarid region. Soil quality outcomes from contrasting long-term conservation and ‘business as usual’ treatments were evaluated near Mandan, ND, USA. Contrasting practices were, a) low vs. high cropping intensity/diversity, b) continuous cropping with and without late-summer seeded cover crops, c) continuous cropping with and without full-season cover crops, and d) continuous cropping with and without livestock integration. A suite of soil physical, chemical, and biological attributes were measured in contrasting treatments over a three-year period (2014-2016) following established methods. Increased cropping intensity/diversity improved soil physical and biological attributes, but increased acidification and enhanced depletion of exchangeable cations. Inclusion of late-summer seeded cover crops had a negligible effect on soil properties, whereas inclusion of full-season cover crops increased enzyme activities and FAME markers for bacteria, actinomycetes, and fungi. Integration of livestock (cattle) decreased sorptivity, implying degradation of near-surface soil physical condition, but increased amino-N, particulate organic matter, and total FAME. Integrative assessments with the Soil Management Assessment Framework suggested soil quality improvements were realized with increased cropping intensity/diversity and full-season cover crops, but not late-summer seeded cover crops or livestock integration. Preliminary results suggest the sustainability of dryland cropping systems can be improved through the use of conservation management practices that increase cropping intensity/diversity and/or include full-season cover crops.