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Nitrogen monitoring for higher yields and greater nitrogen use efficiency

Principal Investigator

Ben Rosser

Research Institution

Ontario Ministry of Agriculture, Food, and Rural Affairs (OMAFRA)

External Funding Partners

Weather INnovations Consulting LP (WIN)

This project was funded in part through Growing Forward 2 (GF2), a federal-provincial-territorial initiative. The Agricultural Adaptation Council assists in the delivery of GF2 in Ontario.

Project Start

April 2015

Project End

October 2017


  • Establish a series of 20 nitrogen (N) monitoring fields across Ontario to measure: accurate rainfall; evaporation/transpiration; temperatures (crop heat units); soil moisture; soil nitrates; field optimum n rates; and corn growth, development and yield.
  • Develop a new soil nitrate survey with several N sampling times repeated through the spring period.


  • The development of improved tools to estimate nitrogen fertilizer requirements taking into account seasonal weather impacts on nitrogen (N) supply will lead to improved nitrogen use efficiency and support for farmers’ decision-making on the most economic fertilizer rate at the most appropriate timing for efficient uptake by the corn crop.
  • The outcomes of the project will be shared broadly with farmers, and can be used to explain to the public how farmers are using well-researched best practices to improve production as well as decrease environmental impacts.
  • This project will serve as a launch pad for a nitrogen monitoring and recommendation network where producers will be able to access in real time, on the internet, the status of nitrogen supply in corn fields.

Scientific Summary

Nitrogen (N) remains a key input in corn and cereal production but determining the rate required remains an elusive target. Weather is a dominant force impacting nitrogen use efficiency in Ontario agriculture. When weather and nitrate supply from the soil are not factored in to N recommendations the risk goes up considerably that N may be over applied and move in to the environment or it will be under applied and put producer’s economic sustainability at risk. It has become clear as a result of previous research that general recommendations that have no weather or soil N status adjustment are limited in predicting correct N rates beyond “the average”. As farmers move to more in-crop nitrogen fertilization strategies (i.e. side-dressing, high clearance injection tool bars, Y-Drops, etc.) the influence of weather on soil nitrogen status and potential crop demand for nitrogen will become more significant factors in attempting to predict the correct N rate. It is imperative that Ontario has a network of sites that can evaluate how weather data, crop and soil factors and recommendation tools can fit together to improve yields and environmental sustainability. It is increasingly apparent that as weather fluctuations become more severe from season to season, recommendation tools will almost certainly need some real time weather or soil N status data to make accurate recommendations.

The project is focused on addressing climate change challenges (precipitation and temperature) and how they impact decisions on nitrogen application rate for high yielding corn, and nitrogen availability throughout the season. The project also addresses the challenge of improving nutrient stewardship in Ontario, applying the right rate of nitrogen at the right time, through development of new tools and recommendations. The project will improve the farmers’ responsiveness to weather events, to reduce environmental risks that can impact the sector or society at large. Yield expectation combined with soil nitrate status work together to produce a much more reliable N recommendation for the side-dress application.