Impacts of Climate Change and Different Crop Rotation Scenarios on Groundwater Nitrate Concentrations in a Sandy Aquifer

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.

Estimation of Watershed Hydrochemical Responses to Future Climate Changes Based on CMIP6 Scenarios in the Tianhe River (China)

“…To sum up, positive climate policies to address greenhouse gas emission controls are important to mitigate increases in TDN fluxes in the future, and more strict management of agricultural land for non-point source control will likely be needed, particularly during the high-flow periods in the summer, to avoid extreme events. It is necessary to project flexible strategies facing the changing climate status in the future to realize a dynamic best management practice including integrated measures [62,63], such as limits on crop fertilization, matching of the timing of fertilizer-to-crop demand, conservation tillage, terraces, and diversions to reduce soil and organic N loss, plant buffer structures, constructed wetlands, and so on.…”

Assessment of Impacts of Climate Change on Tile Discharge and Nitrogen Yield Using the DRAINMOD Model

“…In a study using SWAT model, [70], found that annual P loading would decrease in the future from a watershed in Lake Erie basin due to increased evapotranspiration and decreased snowfall. On the other hand, [14,18,19,68,71,72] all found that nutrient losses may increase in future in Ontario and Quebec watersheds.…”

“…In Canada mainly watershed-scale studies on impacts of climate change on water resources have been completed by [10][11][12][13][14]. In their study on a watershed in Quebec, [10], simulated future streamflows finding a slight decrease in annual runoff.…”

“…Also, in southern Ontario, [13] used model simulations to estimate the increase in winter streamflow in several large watersheds. A future assessment of groundwater nitrate concentrations in a sub-watershed of southern Ontario was conducted by [14]. They found that an agricultural BMP was very effective in reducing nitrate in groundwater under a crop rotation system.…”

Groundwater promotes emergence of asporogenic mutants of emetic Bacillus cereus

“…It is transported from the soil into the groundwater by leaching (Brillard et al ., 2015). Leaching is increased by heavy rainfall and intensive irrigation, both of which will increase with global warming (Zhou et al ., 2010; Green and Anapalli, 2018; Saleem et al ., 2020). In addition to increasing the flow of water through the soil, global warming may affect the diversity of bacteria (Classen et al ., 2015).…”