Intercropping legumes impact on nitrogen cycling and grazing as a form of cover crop termination

Coordinating agronomist: Marika Dewar-Norosky
Organization: Manitoba Organics
Practice: Nitrogen management
Trial started: Spring 2026

Barrier: While agronomically effective in supplying nitrogen, full season green manure years remove land from cash-crop production so they can be perceived as a financial burden. As a result, farmers (organic and non-organic) are hesitant to extend rotations or adopt more complex systems without clear, regionally relevant evidence that these practices can maintain yields and support economic viability.

Description: This field scale trial evaluates a two-year intercropping and grazing system aimed at improving nitrogen management and profitability in grain production. More specifically, it compares: 1) an intercropped yellow pea-oat crop (to be harvested, cleaned and sold as two separate cash crops) with an underseeded cover crop of hairy vetch and subterranean clover and 2) a forage pea-oat green manure (with an underseeded cover crop of hairy vetch and subterranean clover) that will either be a) grazed as a termination method or b) plowed down as a termination method. The following year, a spring wheat crop (which will be harvested as the cash crop) will either be 1) monocropped or 2) underseeded with red clover. The trial, which builds on University of Manitoba small-plot research, will measure soil nitrate, yellow pea-oat and spring wheat yield and biomass, and oat-pea forage and green manure biomass. Analysis will also be completed to determine nitrogen availability and economic viability of the intercrop.

Field-scale evaluation of fall-applied EEFs for seed yield productivity, profitability, and nitrous oxide emissions reduction in multi-year forage and turf seed production systems

Coordinating agronomist: Jo-Anne Relf-Eckstein
Organization: Saskatchewan Forage Seed Development Commission
Practice: Nitrogen management
Trial started: Fall 2026

Barrier: Adoption of enhanced-efficiency fertilizers (EEFs) in multi-year forage and turfgrass crop production faces barriers of high EEF product cost, lack of region-specific evidence of economic or environmental benefit, and uncertainty about real-world performance. As a result, these producers—who have a short frost-free period and a long cold interval between fall fertilizer application and spring crop demand—are hesitant to invest in EEFs without proof of economic and environmental benefit.

Description: This project evaluates standard, fall-applied urea with enhanced-efficiency products in commercial forage and turf grass seed fields, with three randomized replicates. The four treatments used in this replicated trial are: 1) urea at 100% of the recommended rate, 2) urea at 100% of the recommended rate plus a dual inhibitor (SuperU™), 3) urea at 80% of the recommended rate plus the dual inhibitor, and 4) urea at 100% of the recommended rate plus the dual inhibitor plus a spring-applied liquid phosphorus fertilizer (PhosForce). Tissue tests and post-harvest soil nitrate tests will be conducted, and above-ground biomass, seed yield, and seed quality will be measured. Both statistical and economic analyses will also be completed. This will provide producers with valuable data on nitrogen use efficiency and offer practical guidance for those considering the adoption of these nutrient management practices.

Optimizing wheat yield and quality: Farm-scale comparison of blanket vs. variable rate nitrogen strategies across landscape positions

Coordinating agronomist: Lana Shaw
Supporting agronomists: Junaid Afzal and Salman
Organization: South East Research Farm
Practice: Nitrogen management
Trial started: Spring 2026

Barrier: While many wheat producers understand the theory of variable rate nitrogen (VRN),  adoption has been hindered by the uncertainty on the return on investment (the cost of mapping and technology compared to benefits), risk of low protein levels, and a lack of localized data that clearly quantifies the economic benefit of VRN against blanket rates.

Description: This replicated block design farm-scale trial compares the standard blanket nitrogen rate to a variable rate nitrogen (VRN) application in two topographically variable, rainfed Canada Western Red Spring (CWRS) wheat fields in the Black soil zone of southeast Saskatchewan. In addition to in-crop monitoring, yield, quality, protein, and nitrogen use efficiency (NUE) will be reported across low, mid, and high landscape slope positions. The economic return ($/ac) of each application rate strategy will be determined, based on site-specific performance.

Nitrogen EEFs in northeast Saskatchewan: What is the impact on nutrient management and profitability?

Coordinating agronomist: Ishita Patel
Supporting agronomist: Lauriche De Villa
Organization: Northeast Agriculture Research Foundation
Practice: Nitrogen management
Trial started: Spring 2026

Barrier: Unpredictable weather, increased input costs, and high land rental/mortgage costs are all challenges for farmers on unirrigated land in Northeast Saskatchewan, in addition to balancing production, profitability, and environmental impacts. While there is interest in using nitrogen enhanced efficiency fertilizers (EEFs), inconsistent messaging on the economic feasibility of these products, along with uncertainty related to their performance on soils with high organic matter (6-10% OM), has hampered farmers from trying them.

Description: This field trial will be set up in a randomized complete block design that includes four replicates and five treatments: 1) dual inhibitor product (Active Stabilizer Plus), side-banded at 75% of the recommended nitrogen rate, 2) a 50:50 blend of ESN and conventional urea side-banded at 75% of recommended nitrogen rate, 3) untreated urea at 75% of recommended nitrogen rate and a humic acid product (Resurge by Helena Agri Enterprises) at label-recommended rate (both side-banded), 4) untreated urea check side-banded at 100% of the recommended nitrogen rate, and 5) an anhydrous ammonia check, mid-row banded at 100% of the recommended nitrogen rate. Spring LibertyLink canola will be seeded and tissue tests (at bolting), yield, grade, oil, and protein content will be measured, as well as post-harvest soil nitrate levels. Economic analysis for treatment will also be conducted.

Refining nitrogen rates for spring wheat on high-organic-matter soils in the Bas-Saint-Laurent

Coordinating agronomist: Audrey-Anne Pelletier
Organization: JMP Consultants
Practice: Nitrogen management
Trial started: Spring 2026

Barrier: Spring wheat producers in the Bas-Saint-Laurent region often farm G2 and G3 soils with more than 4% organic matter, but the new MAPAQ nitrogen guidelines adjust for organic matter only in G1 soils. As a result, standard recommendations may overestimate nitrogen needs in the region. While tight profit margins make producers reluctant to reduce rates without regional, spring wheat-specific evidence that yield can be maintained, lowering in-crop nitrogen could reduce fertilizer costs and improve profitability.

Description: Field trials on two farms will compare four nitrogen treatments in spring wheat. The control will receive up to 60 kg N/ha (54 lbs N/ac) at seeding with no additional nitrogen, while the other treatments will receive the same rate at seeding followed by post-emergence applications at Zadoks stage 26 of 30, 45, or 60 kg N/ha (27, 40 or 54 lbs N/ac). Soil and plant tissue nitrate levels, plant population, pest and weed pressure, grain yield, protein, and test weight will be assessed. An economic analysis will compare treatments to evaluate whether post-emergence nitrogen can be reduced on high-organic matter G2 and G3 soils without reducing profitability.

Optimizing nitrogen application in corn while improving operational efficiency and reducing environmental impacts

Coordinating agronomist: Marie-Laurence Côté
Organization: Groupe Envir-Eau-Sol Inc.
Practice: Nitrogen management
Trial started: Spring 2026

Barrier: Applying some nitrogen (N) after corn emergence may better align nitrogen availability with periods of high crop demand, but the timing can conflict with time-sensitive field operations, such as first-cut hay on dairy farms. Applying all N before emergence may improve operational efficiency for these farms, particularly when combined with planting and strip-till in a single pass, while polymer-coated urea may help extend nitrogen availability. Producers lack regional data on whether this approach can maintain yield and provide an agronomically, economically, and environmentally viable alternative.

Description: A strip trial conducted in two fields on a commercial dairy and cash crop farm in Quebec will compare two corn nitrogen strategies at similar total nitrogen rates. The control will include starter fertilizers banded at planting, followed by a post-emergence blend of urea and ammonium sulfate around the V6 stage. In the treatment strips, starter fertilizers and a 50:50 blend of polymer-coated urea and conventional urea will be applied in a single pass, combining planting and strip-tillage, with no post-emergence nitrogen application. Crop performance, nitrogen dynamics, labour, fuel use, treatment costs, and potential greenhouse gas emissions will be assessed to compare the agronomic, operational, economic, and environmental trade-offs of the two strategies.

Sulfur fertilization and overseeding to maximize symbiotic nitrogen fixation in pastures

Coordinating agronomist: Frédérique Lavallée
Organization: Écoboeuf
Practice: Nitrogen management, Rotational grazing
Trial started: Spring 2026

Barrier: Mixed legume-grass pastures are the norm for many beef producers and can supply nitrogen through symbiotic fixation. However, sulfur deficiencies can reduce legume vigour, resulting in declining pasture productivity, leading more producers to consider synthetic nitrogen fertilizer. Although synthetic nitrogen can increase forage yield, it carries economic and environmental costs and can further reduce legume content in mixed stands. Producers lack regionally relevant, commercial-scale evidence that sulfur fertilization combined with legume overseeding can sustain pasture productivity and reduce reliance on synthetic nitrogen.

Description: A randomized field trial on a commercial beef farm in Quebec’s Clay Belt region will evaluate whether sulfur fertilization can improve legume establishment, symbiotic nitrogen fixation, and forage productivity under rotational grazing. Overseeded pasture plots will receive either potassium sulfate, a fast-release sulfur source; lower-cost, slow-release elemental sulfur; or no sulfur fertilizer. Legume establishment, composition, forage yield and quality, and treatment economics will be assessed to determine whether correcting sulfur deficiencies can help mixed pastures provide a practical and economically viable alternative to synthetic nitrogen fertilization.

Evaluation of Dual Inhibitor EEF on Winter Wheat Production

Coordinating agronomist: Steve Watts
Organization: Genesis Crop Systems
Practice: Nitrogen management
Trial started: Spring 2026

Barrier: Limited access to independent, on-farm information about the performance and cost-effectiveness of utilizing enhanced efficiency fertilizers in winter wheat production is a key barrier to adoption in Prince Edward Island. The higher per unit cost associated with these products may discourage farmers from trying them without regionally relevant evidence and/or results from their own operations that demonstrate that using an EEF can reduce total nitrogen application rates and passes across the field while maintaining yield, grain quality, practicality, and profitability.

Description: Field-scale replicated trials will be conducted on six farming operations to evaluate how using a dual-inhibitor nitrogen fertilizer, such as SuperU, to reduce total nitrogen rates in winter wheat affects crop performance, profitability and operational efficiency. Each farm will compare three treatments: 1) the grower’s standard nitrogen management practice; 2) a treatment receiving approximately 20% less total nitrogen, with a dual-inhibited nitrogen source applied at green-up supplying approximately 30–45% of the total nitrogen; and 3) a treatment receiving the same reduced total nitrogen rate without an inhibited nitrogen product. Farmer observations will assess ease of application and adoption, while grain yield, dry matter, bushel weight, protein content, and treatment economics will also be evaluated. 

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.