Ontario corn farmers continue to apply the majority of the crops nitrogen (N) needs prior to planting as a broadcast and worked in application of urea and to a lesser extent urea ammonium nitrate (UAN). Little if any management decisions other than yield goal target are used in the selection of N rates.
Significant advancements in nitrogen management can be made if we improve upon the current tools used for estimating fertilizer N requirements (Corn N Calculator, Pre-Sidedress Nitrate Testing, manure nutrient analysis, etc.) This improvement can be made by addressing the seasonal or weather impacts on both soil nitrogen supply and crop demand.
In previous years OMAFRA Field Crop Unit staff in partnership with producers, agri-business and SGS labs has conducted an annual one day survey of soil N levels across the province. While this has been of value to a range of users, the single day nature of the soil N levels has limited use as a single point in time measurement when soil N dynamics change quickly with time and climatic conditions.
The ongoing intensive monitoring of soil N levels over the early-mid growing season at a number of dedicated locations with up to the minute weather reporting to enable the soil N results to be explained in relation to the weather was thought to be a better way to assess soil N dynamics.