Measuring the impact of different proportions of legumes in cover crop mixes on nitrogen credits in a subsequent corn crop

Coordinating agronomist: Florence Pomerleau-Lacasse
Organization: Agri Conseils Maska
Practices: Cover crops, nitrogen management
Trial started: Fall 2025

Barrier: Leguminous cover crops can supply nitrogen to the following crop and potentially reduce synthetic fertilizer needs, but legume cover crops can have a wide range of seed costs depending on species. There is a lack of local data on what species and proportion of legumes optimize biomass, nitrogen contribution and economic return.

Description: On four farms, two cover crop mixes (oats, radish and forage peas or fava beans) will be planted side by side after a cereal crop with <50% legumes and >70% legumes. Cover crop biomass and quality will be measured. In the subsequent corn crop, test strips with only starter fertilizer will be compared to standard rates. Changes in soil nitrate, corn stalk nitrate, and corn yield will be measured, and the economics evaluated to determine the legume proportion that delivers the best agronomic and economic value.

Evaluating nitrogen credits from leguminous cover crops in colder regions to guide nitrogen fertilizer management in potatoes

Coordinating agronomist: Yolaine Filion
Organization: Club d’encadrement technique pommes de terre
Practices: Cover crops, nitrogen management
Trial started: Fall 2025

Barrier: Potatoes are heavy feeders, and under- or over-applying nitrogen can affect plant health, yield and quality. In colder regions with shorter growing seasons, uncertainty about nitrogen credits from leguminous cover crops makes it difficult for potato growers to confidently adjust synthetic nitrogen fertilizer rates.

Description: This replicated split-plot trial will compare a legume cover crop (forage peas) seeded after canola harvest with a no cover crop control. Three post-emergence nitrogen (N) rate treatments will be applied: the grower’s standard nitrogen rate and two reduced rates (15 kg N/ha and 30kg of N/ha below standard). Cover crop biomass, soil and petiole nitrate levels and potato yield and tuber quality will help quantify nitrogen credits, while an economic analysis will evaluate the feasibility of adjusting synthetic fertilizer rates accordingly.

Adaptive nitrogen trials in corn following cover crops

Coordinating agronomists: Lorraine Vandermyden, Jackie Clark
Organizations: The Ontario Soil Network and Ecological Farmers Association of Ontario
Practices: Cover crops nitrogen management
Trials started: Summer 2025 and Summer 2026

Barrier: Nitrogen is a critical and costly input, with economic and environmental consequences if not managed carefully. As farmers adopt beneficial management practices such as cover cropping to improve nutrient cycling and increase flexibility in nitrogen management, the lack of local, field-level data on how much nitrogen can be reduced in corn following a legume cover crop without compromising yield or profitability remains a key barrier.

Description: This replicated strip trial will be conducted on 12 farms across Ontario and will compare the farmers’ standard nitrogen (N) application rates with reduced nitrogen application rates (by at least 20 lbs N/acre) in corn following cover crops. Farms may choose to include a zero/near-zero nitrogen control. Yield, soil, and economic data will be combined with farmer observations to understand outcomes.

Evaluating the profitability and productivity of enhanced efficiency fertilizers (EEFs) on irrigated winter wheat systems

Coordinating agronomist: Jamie Puchinger
Organization: Farming Smarter
Practice: Nitrogen management
Trial started: Fall 2025

Barrier: There is limited data on the cost-benefit analysis of the use of EEFs on a fall-seeded winter wheat crop under irrigation in the Prairies.

Description: This study aims to evaluate the use of EEFs in irrigated winter wheat systems in southern Alberta. A replicated strip trial will compare two rates of fall-applied urea (at 100% and 80% the recommended rate) with and without the use of a dual inhibitor (Anvol and Centuro U-Pro) to a check (with no nitrogen). Soil samples, emergence counts, canopy closure, vigour, biomass and aerial imagery will be captured in this trial. Grain yield and quality will also be measured and nitrogen use efficiency and profitability will be calculated. The project assesses strategies to reduce nitrogen losses, reduce operational expenses while maintaining yields for overall increased profitability.

Examining the impacts of reduced nitrogen rates in a cereal-based rotation with under-sown clover as a cover crop

Coordinating agronomist: Lana Shaw 
Organization: South East Research Farm Inc.
Practices: Cover crops, nitrogen management
Trial started: Spring 2026

Barrier: There is concern about the economic risk of reducing nitrogen fertilizer rates in cereals with under-sown clover.

Description: This trial evaluates reduced nitrogen rates (70% of standard) combined with under-sown clover (red clover) in a rain-fed oat production system. It will assess impacts on nitrogen use efficiency, cereal yield and quality, nitrogen credits from the red clover to the subsequent crop, and the profitability of intercropping, providing practical evidence for adopting these integrated practices.