Written by: Kelsey Banks, Ottawa-Rideau Regional Communication Coordinator                  Previous       Next 

As part of the OSCIA’s annual meeting on February 8, 2022, attendees were presented with data and further information on fertilizer efficiency in field crops. This topic was presented by Dr. Claudia Wagner-Riddle, Professor and Research Leadership Chair with the School of Environmental Sciences at the University of Guelph, and Dr. Alfons Weersink, professor of agri-environmental policy, farm structure and production economics at the University of Guelph.

Dr. Wagner-Riddle began the discussion by presenting “Practices for fertilizer emission reductions in crop production”.

Nitrogen (N) is a mobile nutrient that can be lost throughout the N cycle by denitrification, volatilization, immobilization or leaching. Focusing on N losses on-farm and in relation to greenhouse gas (GHG) emissions, the main GHG emissions coming from a farm are enteric fermentation emitting methane, manure and emitting nitrous oxide and methane, and soils emitting nitrous oxide. When the soil is emitting the N source from the soil as nitrous oxide, that is called volatilization. Leaching is when the N source is exposed to a high amount of water the nitrates can move by water into groundwater causing groundwater contamination.

Right now, one of the main topics of global discussion is carbon emissions and carbon credit programs. Dr. Wagner-Riddle said, “We need to focus on not just carbon management, but also nitrogen management.”

So, what practices can growers do to reduce fertilizer emissions? The main strategy that was discussed is to manage the fertilizer plan using the 4R strategy.

Here is where the focus should be according to the 4R’s:

1. Right Time – when it comes to planning N application, consider split application in corn. Corn will rapidly uptake the N most at V6–V8 stages.
2. Right Source – use the best source of N available to you and use an inhibitor to reduce the loss.
3. Right Place – focus on the best way to place the N in the crop so it is utilized to the best of its ability while being safe for the crop.
4. Right Rate – right now, this is not being as focused on as much as it could be, and growers should consider looking at their fertilizer strategy and seeing if the rate can be lowered.

Corn emits approximately 2.6 times more nitrous oxide than soybeans do so it is important to keep these facts in mind when planning your corn fertilizer strategy. Soybeans do emit some nitrous oxide, but to reduce the amount emitted growers should consider adding cover crops and winter wheat to their crop and fertilizer plans.

Dr. Weersink continued the fertilizer efficiency conversation through a presentation on the production economics behind N usage and efficiency. Some farmers are using too much N and it surpasses the Most Economical Rate of N (MERN). Most farmers do not want to lower the rate of N they are using because of the following factors:

1. The time pressures faced at planting. There is very little time for precision across and within fields.
2. “The value farmers associate with a loss is greater than the value associated with a gain of the same dollar amount” – Dr. Weersink
3. “The intrinsic value of a good-looking crop” – Dr. Weersink

From a production economics and environmental perspective, lowering the N rate is the most effective means of reducing GHG emissions. Dr. Weersink concluded his presentation by saying, “However, a number of economic and behavioural factors also influence actual N use decisions.”

If you have any questions, please contact your local OSCIA committee for the contact information of Dr. Claudia Wagner-Riddle and Dr. Alfons Weersink.

The full video presentation of this session is available on the OSCIA membership platform as a membership benefit. Login here: https://membership.ontariosoilcrop.org/member-home/

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