Changing agricultural landscapes and groundwater quality in sensitive aquifers

Principal Investigator

Jana Levison

Research Institution

University of Guelph

External Funding Partners

Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) New Directions; Dairy Farmers of Ontario; Ontario Federation of Agriculture (OFA); Fertilizer Canada

Project Start

January 2014

Project End

February 2017


  • Study groundwater quality under corn-soybean-wheat rotation scenarios such as: i) cash crops only; ii) including green manures with fall termination after wheat in contrast to fields receiving manure; iii) increased tile drained area; and iv) simulating extreme storm events following nutrient application.
  • Determine critical or threshold scenarios to mitigate nutrient transport to sensitive groundwater bodies.
  • Examine several geological conditions encountered across Ontario including: i) sandy aquifers; ii) thin sediments overlying fractured bedrock aquifers; and iii) thick sediments overlying fractured bedrock aquifers.
  • Identify critical cases for sensitivity to contamination using numerical modelling supported by field research.
  • Provide recommendations for nutrient management policies.


  • The improved understanding of the transport of nitrate from the surface to groundwater related to crop and weather changes at three locations in southern Ontario may contribute to recommendations about how land use practices may be adjusted, if needed, to mitigate rural water quality impacts.

Scientific Summary

In Ontario, groundwater is the main, and often only, water source for farm use and rural residents. While agricultural activities and climate are changing, it is essential that groundwater quality is continually protected. In Ontario, acreages for corn, soybean and winter wheat are increasing while production of certain livestock (i.e., beef and dairy cattle, pigs) is decreasing. It is more sustainable – that is, less expensive, more socially responsible and better for the environment – to maintain a clean groundwater supply than to treat water once it has been contaminated. With more cash crops requiring nutrient inputs and less manure available, as well as the desire for increased yields, more synthetic nutrients may be applied. Weather patterns with more intense storms could also impact nutrient fate in the environment. A comprehensive understanding of evolving cropping systems of corn-soybean-wheat production and their potential impact on groundwater quality in various geological conditions encountered across Ontario is necessary to ensure sensitive rural water supplies are continually protected for agricultural and potable water uses.

The project aims to define and quantify the transport of excess nutrients, specifically nitrate from nitrogen application, related to cash cropping into groundwater to anticipate and reduce any potential impacts on water quality. Advanced computer modelling of groundwater systems, agricultural nutrient management expertise and well water monitoring data will be used together to find critical cases for sensitivity to contamination. Various soils and geological conditions found across Ontario at three study locations will be characterized and used in the models. The results can be applied to nutrient management policies and to help to improve “right time, right place, right rate” application principles for Ontario grain farmers. This research will contribute to knowledge surrounding on-farm initiatives such as nutrient management plans and farm wellhead protection. Groundwater is a resource important for farm viability in Ontario, and results of this research will contribute to groundwater protection initiatives related to changing agriculture.

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