A Systems Perspective on the Effects of Grazing on Soil Water and Other Ecosystem Services.

There is growing interest in how grazing management could be improved as a tool for both climate change adaptation and mitigation, yet it remains unclear which practices could achieve these goals and to what extent. With respect to climate change adaptation, one of the biggest challenges is likely to be increased rainfall variability, which exposes agricultural systems to greater risks related to flooding and drought, both of which affect productivity and environmental outcomes. These threats indicate that it is critical to think not only about how practices can alter soil carbon or net greenhouse gas emissions, but also about the potential implications for water resources and farm-scale profitability. The goal of this study is to better understand how grazing management affects soils water dynamics, in light of other potential ecosystem service tradeoffs. To address this question, we are conducting a global meta-analysis that includes grazing management practices as part of broader range of soil conservation practices. To date, the full analysis includes 83 studies (>350 paired observations), of which 11 are directly related to grazing. Grazing impacts were divided into four distinct management regimes: reducing stocking rates, moving from continuous grazing to more complex (rotational) grazing, integrating animals into cultivated lands, and integrating animals into uncultivated lands. Preliminary findings indicate significant variability, but suggest that integrating livestock into cultivated lands tends to decrease infiltration (-12%), whereas decreasing stocking rates or increasing the complexity of management can increase infiltration (+21%). Although adding animals to uncultivated systems had an undesirable impact on infiltration, findings provide some evidence that incorporating other soil conservation practices (planting perennials,  agroforestry,  rotating crops) might help to mitigate those effects. These results will be presented in the context of climate change and economic considerations that could be associated with changes in management that influence soil water properties.