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An early season nitrogen test to help Ontario cereal growers decide whether or not to side-dress with nitrogen fertilizer

Principal Investigator

Manish Raizada

Research Institution

University of Guelph

External Funding Partners

International Plant Nutrition Institute (IPNI); National Sciences and Engineering Research Council of Canada’s Collaborative Research and Development program (NSERC-CRD); Ontario Agri-Business Association (OABA); Ontario Trillium Scholarship from the Government of Ontario; Ontario Ministry of Food, Agriculture and Rural Affairs (OMAFRA)

Project Start

March 2014

Project End

April 2018


  • Evaluate whether biosensor bacteria called GlnLux can be used by a grower to decide whether or not (or how much) to side-dress with nitrogen.
  • Determine whether results from GlnLux can be used to make a decision on nitrogen side-dressing that optimizes corn yield and maximizes the cost:benefit ratio of nitrogen application (MERN).
  • Compare the GlnLux test to other available technologies (SPAD meter, Greenseeker, standard soil N tests), so that researchers and growers can make an informed decision as to which test to use.


  • The development of an accurate and affordable GlnLux nitrogen fertilizer diagnostic will help growers know how much nitrogen fertilizer to apply during the mid-season (side-dress stage) to make better nutrient management decisions on their farm, maximizing their return on investment while reducing their environmental impact.

Scientific Summary

Nitrogen is one of the most essential nutrients (fertilizer) for crop production. Farmers strive to apply nitrogen in the most efficient way to satisfy cropping needs while being economically efficient. As a result of uncontrollable factors such as weather, nitrogen has the ability to be lost into the environment. Some grain farmers in Ontario apply all of their crops nitrogen upfront in a single pass when the plant is in its early growth stages. In order to improve nutrient use efficiency, farmers are beginning to apply nitrogen in multiple applications throughout the plants growth cycle. However, affordable diagnostic tools are needed to improve farmers’ ability to splitting their nitrogen fertilizer application into multiple applications. This requires an accurate pre-plant equivalent of a soil test, and a nitrogen test for mature plants to help growers add the most economically and environmental sustainable nitrogen rates at each plant stage. Current in season diagnostic tests using direct soil nitrogen testing include SPAD or Greenseeker®, which are reported to be ineffective during the early part of the growing season.

To assist Ontario corn growers, we are creating an alternative approach to early season nitrogen testing which measures leaf concentrations of the amino acid glutamine, an excellent indicator of plant nitrogen status. We have created a rapid test for leaf glutamine based on a biosensor bacterium called GlnLux. In this test, a grower simply uses a paper punch to remove a small disc from a crop leaf. While the test was previously optimized under controlled greenhouse conditions, this grant is intended for the investigation of its usefulness under field conditions. Two field seasons of sample and data collection have now been completed, with exciting results. Based on our results thus far, we have reason to think that the GlnLux test may be better than some commercial tests at certain points in the growing season with respect to predicting final grain yield as a result of the early season nitrogen status.

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