CFCRA Corn Project: Activity 2 – Cross Canada agronomic and environmental benefit of advanced 4R nitrogen management of grain corn

Objectives:

• Determine if advanced 4R nitrogen (N) management for Quebec (QC), Ontario (ON), and Manitoba (MB) conditions changes the most economical rate of N (MERN) and improves grower return on investment (ROI).
• Determine if advanced 4R N management for QC, ON, and MB conditions reduces N losses to the environment.
• Determine if a novel practice of double vs single injection bands in combination with depth placement and N source reduces N losses and increases corn grain yield in Ontario.
• Develop advanced grower tools for in-season N rate determination.

Impacts:

This research met an important need to increase the use efficiency of nitrogen fertilizers to hold or reduce nitrogen fertilizer rates in grain corn without decreasing yields.

Scientific Summary:

This activity aimed to develop advanced 4R (Right Source, Right Rate, Right Time, and Right Place) nitrogen (N) management strategies for Canadian corn producers to enhance productivity and environmental performance (nutrient leaching and GHG emissions) for N-intensive corn production. Specifically, the project explored the economic and environmental impacts of advanced 4R nitrogen management practices with grain corn and examined whether in-season nitrogen testing and rate adjustments should be included in advanced 4R practices. Four high-efficiency fertilizers were compared to liquid urea ammonium nitrate fertilizer at planting: ESN, SuperU, Agrotain and Agrotain+ across sites in Ontario, Quebec and Manitoba.

Results: Research Highlights (2018-2023)

Nitrogen application; source, timing and placement studies

Specifically in Ontario, single/double injection bands were compared with broadcast applications regarding nitrogen losses and grain yield.

In 2018, broadcast surface application of urea and SuperU without incorporation gave lower yields than single and double slot injection of UAN, with or without Agrotain+. SuperU provided yields on par with side-dressing of UAN at the highest rate.

In 2019, broadcast application of urea and SuperU outperformed injected UAN sources in terms of yield, and double slot injection of UAN sources was better than single-slot.

In 2020, yields were higher with an in-season application of UAN (either single or double slot injection) compared to broadcast application at planting.

With respect to emissions, in 2020, Agrotain+ reduced nitrous oxide (N₂O) more for double-slot than with single-slot injections. For ammonia emissions, SuperU reduced these with broadcast application at planting, but single or double injection of UAN was even more effective.

In Quebec, corn grain yield was greater across all three years (2018, 2019 and 2020) when nitrogen fertilizer was split in two applications rather than broadcast on the field before planting. Split application delivered 25% of the recommended nitrogen fertilizer in the form of urea within 5 cm of the corn seed at planting. The remaining 75% of the required nitrogen was applied as a liquid urea ammonium nitrate solution when corn reached the V5-V6 growth stage. Corn grain yield was greater (2018) and tended to be higher (2019, 2020) when urea ammonium nitrate was injected at a depth under 5 cm compared to being dribbled on the soil surface, or injected at a depth deeper than 5 cm.

The urea and nitrification inhibitors in Agrotain and Agrotain+ were associated with more corn grain yield at higher N application rates in 2018 and 2019, but not in 2020 due to the weather conditions in Quebec.

In terms of application timing, in Manitoba, results showed that delaying split nitrogen applications (after V4 stage) did not improve corn yields compared to earlier split nitrogen applications. However, in Ontario and Quebec, a more positive response to later nitrogen application (V8 to V12) was observed, due to regional differences in climate.

Optimal nitrogen application rate for grain corn using in-field measurements

In Quebec, studies showed that the use of near infrared spectroscopy (NIRS), Greenseeker and other reflectance sensors prior to post-emergence application of nitrogen fertilizer did not improve the determination of the optimal nitrogen rate for corn.

The use of nitrogen nutrition index (NNI) alone also did not result in an effective determination of the optimum nitrogen rate for corn. Results suggest that a more effective diagnosis would need to consider the lower and upper parts of the corn plant in order to detect nitrogen deficiencies in corn.

Optimal nitrogen application rate for grain corn using modeling

An optimal nitrogen application rate for grain corn can be determined using modelling at the V8 growth stage. The model incorporates many parameters, ranging from precipitation, light, soil pH, soil phosphorus, potassium, calcium, and aluminum content to corn plant nitrogen, corn aerial biomass, and soil carbon and sand. The model takes into account data from this study, as well as data from other ongoing projects. The relationship was found to be valid even when combining contrasting data from sites located in both Manitoba and Quebec, thereby potentially developing a predictive model for all of Canada. The model is currently being validated at the Quebec Research and Development Centre, Agriculture and Agri-Food Canada.

Overall, modelling analysis using traditional data related to soil, climate, and plants was found to be more effective than using NIRS and light reflectance when predicting the optimum nitrogen rate for corn. This is likely due to the fact that a single parameter, whether NNI, soil nitrate content, or reflectance at a certain wavelength of foliage, rarely, if ever, directly determines the optimal nitrogen rate for corn production. It is more reliable for a multitude of parameters to be used together, simultaneously, and factors that maximize crop yields are multifactorial, comprising soil phosphorus concentration, soil pH, calcium, magnesium and other vital elements.  

External Funding Partners:

Funding for the Corn Project was provided by the Agriculture and Agri-Food Canada AgriScience Program through the Canadian Agricultural Partnership, with industry support from the Canadian Field Crop Research Alliance (CFCRA) whose members include: Atlantic Grains Council; Producteurs de grains du Quebec; Grain Farmers of Ontario; Manitoba Corn Growers Association; Manitoba Pulse & Soybean Growers; Saskatchewan Pulse Growers; Prairie Oat Growers Association; SeCan; and FP Genetics. Additional industry funding beyond the core CFCRA members was provided by organizations representing the Canadian fertilizer industry.

Project Related Publications:

None.