Potential Water Quality Outcomes from Integrated Crop-Livestock Systems in the Northern Great Plains.

A growing global population has placed increased pressure on the agriculture sector to produce an increasing amount of food products while increasing environmental sustainability. Integrated crop-livestock (ICL) systems have the potential to achieve environmentally sustainable production of crop and livestock products with studies indicating improved soil health in these systems. However, impacts of ICL systems on water quality and aquatic ecosystems have not received much attention. Objectives include: 1) examining effects of management practices commonly used in ICL systems (e.g., no till, cover crops, livestock grazing) on surface water quality in the Northern Great Plains ecoregion of North America and, 2) identifying information gaps regarding water quality associated with ICL systems and research needs in this area. In general, management practices used in ICL systems reduced losses of total suspended solids, N, and P in surface runoff and soil leachate. However, certain management practices (e.g., no/reduced tillage) reduced losses of TN (relative median change = -65%) while soluble P losses in runoff increased (57%). Conversely, practices such as grazing increased median total suspended solids (22%), NO₃^- (45%), TN (85%), and TP (25%) concentrations and loads in surface runoff and aquatic ecosystems. In ICL systems, a combination of management practices is used and their combined impacts on surface water quality and soil leachate are generally unknown. To close this information gap, future studies should focus on determining concentrations and loads of total suspended solids, N, P, and organic carbon in runoff and soil leachate from ICL systems. This will allow the agricultural community to better assess the environmental sustainability of ICL systems and improve management practices through adaptive management with regards to water quality issues.