|KUMAR, SANDEEP - South Dakota State University|
Submitted to: Journal of Environmental Quality
Publication Type: Review Article
Publication Acceptance Date: 10/15/2017
Publication Date: 1/12/2018
Citation: Faust, D.R., Kumar, S., Archer, D.W., Hendrickson, J.R., Kronberg, S.L., Liebig, M.A. 2018. Integrated crop-livestock systems and water quality in the Northern Great Plains: Review of current practices and future research needs. Journal of Environmental Quality. 47:1-15. https://doi.org/10.2134/jeq2017.08.0306.
Interpretive Summary: A growing global population has placed increased pressure on the agriculture sector to produce an increasing amount food and fiber products and to do so in an environmentally sustainable manner. Integrated crop-livestock (ICL) systems hold potential to achieve environmentally sustainable production of crop and livestock products as studies have indicated improved soil health in ICL systems, but there is a lack of information regarding impacts to water quality. Published research on water quality outcomes from management practices used in ICL systems was reviewed and summarized for application to the northern Great Plains of North America. In general, management practices used in ICL systems reduced losses of total suspended solids, nitrogen, and phosphorus in surface runoff and soil leachate. However, certain management practices (e.g., no/reduced tillage) reduced losses of nitrogen, while phosphorus losses in runoff increased. Furthermore, practices such as grazing increased total suspended solids, nitrogen, and phosphorus losses in surface runoff and aquatic ecosystems. Accordingly, water quality tradeoffs associated with management practices used in ICL systems need to be taken into account when deploying practices on working farms. This review identified three major research needs associated with water quality in ICL systems in the northern Great Plains: 1) quantify surface runoff water quality associated with crop rotation and intercropping and on soil leachate water quality associated with cover crops, no/reduced till, and grazing, 2) increase emphasis on collection of water quality data in ICL systems, especially in the face of projected increases in rainfall amount and intensity due to climate change, and 3) maintain long-term (7-10 year) data collection efforts.
Technical Abstract: Integrated crop-livestock systems hold potential to achieve environmentally sustainable production of crop and livestock products. Although previous studies suggest that integrated crop-livestock systems improve soil health, impacts of integrated crop-livestock systems on water quality and aquatic ecosystems are largely unknown. This review (i) summarizes studies examining surface water quality and soil leachate for management practices commonly used in integrated crop-livestock systems (e.g., no-till, cover crops, livestock grazing) with emphasis on the Northern Great Plains ecoregion of North America, (ii) quantifies management system effects on nutrient and total suspended solids concentrations and loads, and (iii) identifies information gaps regarding water quality associated with integrated crop-livestock systems and research needs in this area. In general, management practices used in integrated crop-livestock systems reduced losses of total suspended solids, nitrogen (N), and phosphorus (P) in surface runoff and soil leachate. However, certain management practices (e.g., no-till or reduced tillage) reduced losses of total N (relative median change = -65%), whereas soluble P losses in runoff increased (57%). Conversely, practices such as grazing increased median total suspended solids (22%), nitrate (45%), total N (85%), and total P (25%) concentrations and loads in surface runoff and aquatic ecosystems. An improved understanding of the interactive effects of integrated crop-livestock management practices on surface water quality and soil leachate under current and future climate scenarios is urgently needed. To close this knowledge 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 integrated crop-livestock systems.