Abstract
Nitrate in groundwater is a major concern in agricultural sub-watersheds. This study assessed the impacts of future climate and agricultural land use changes on groundwater nitrate concentrations in an agricultural sub-watershed (Norfolk site) in southern Ontario, Canada. A fully integrated hydrologic model (HydroGeoSphere) was used in combination with the root zone water quality model (RZWQM2) (shallow zone) to develop water flow and nitrate transport models. Three climate change models and three crop rotations (corn-soybean rotation, continuous corn, corn-soybean-winter wheat-red clover rotation) were used to evaluate the potential impact on groundwater quality (nine predictive scenarios). The selected climate change scenarios yielded less water availability in the future period than in the reference period (past conditions). The simulated nitrate nitrogen (Nitrate-N) concentrations were lower during the future period than the reference period. The continuous corn land use scenario produced higher Nitrate-N concentrations compared to the base case (corn-soybean rotation). However, the best management practices (BMP) scenario (corn-soybean-winter wheat-red clover rotation) produced significantly lower groundwater nitrate concentrations. BMPs, such as the one examined herein, should be adopted to reduce potential negative impacts of future climate change on groundwater quality, especially in vulnerable settings. These findings are important for water and land managers, to mitigate future impacts of nutrient transport on groundwater quality under a changing climate.
Highlights
Climate has always played an important role in the agriculture industry and has shaped the outlook of agriculture all over the world [1,2]
The envelope of uncertainty for Pnet illustrated that the growing season (May to October) has less available water for potential surface runoff and groundwater recharge; the actual rate of availability depends on which model represents the future climate conditions more accurately (Figure 6c)
The focus of this research was to predict the impact of different land use and climate change scenarios on groundwater elevations and Nitrate-N concentrations in a shallow, sandy aquifer setting in an agriculture-dominated sub-watershed in southern Ontario, Canada
Summary
Climate has always played an important role in the agriculture industry and has shaped the outlook of agriculture all over the world [1,2]. Farmers select their crops based on climatic factors such as annual rainfall, low and high temperatures, and growing season length [3,4]. Conventional farming practices in some locations were to apply fertilizers uniformly at high rates without considering the crop and soil requirements [7,8,9] resulting in leaching of excess nutrients to groundwater especially after a heavy rainfall event [9]. It is necessary to evaluate the impact of land and crop management practices on groundwater quality under changing climate conditions
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