Grazed Berseem Clover for Soil Health and Weed Suppression in Organic and Conventional Rotations of the Inland West

Commodities

• Agronomic: clovers, hay, medics/alfalfa

Practices

• Animal Production: grazing management
• Crop Production: cover crops, nutrient cycling
• Education and Training: extension, farmer to farmer, on-farm/ranch research, workshop
• Soil Management: soil quality/health

Field bindweed (Convolvulus arvensis) and other persistent perennial and annual weeds remain major barriers to sustainable crop production across Eastern Oregon and Western Colorado, especially in irrigated alfalfa systems under both organic and conventional management. These weeds reduce stand vigor and forage yield, increase reliance on tillage and herbicides, and complicate organic transition due to deep root systems and long-lived seedbanks. In these regions, irrigation water can further spread weed seeds, accelerating reinfestation. Preliminary grower observations suggest promising solutions: a producer near Ontario, Oregon, reported that a small planting of 'Frosty' berseem clover nearly eliminated morning glory pressure. Berseem, also known as Egyptian clover, is a fast-growing, nitrogen-fixing annual legume that reportedly suppresses weeds through rapid canopy closure and high biomass while improving soil health by enhancing nitrogen availability, organic matter, and beneficial microbial activity. Its high forage quality and low bloat risk also make it well-suited for integrated crop-livestock systems common in alfalfa-based rotations.

This project evaluates whether fall-planted berseem clover, managed with and without grazing during the cover crop phase, and its use as a nurse crop during alfalfa establishment, can suppress field bindweed, improve soil biological and physical health, and enhance whole-farm economics in alfalfa production systems. On-farm trials will be conducted in two irrigated regions-the Treasure Valley (Oregon) and Grand Valley (Colorado). The experiments will be conducted using a Randomized Complete Block Design with split plots with four replications. Main plot treatments include berseem monoculture and berseem-triticale mixtures, each with and without managed grazing, along with a no-cover control. Subplots will consist of alfalfa monoculture and an alfalfa-berseem clover mixture (80:20). Multi-year measurements will quantify cover-crop performance, weed suppression, soil health indicators, and subsequent alfalfa establishment, yield, and forage quality. Economic analyses will estimate nitrogen credits, forage and nutritive value, fertilizer savings, and weed-control cost offsets. Results will support a practical Clover Return-on-Investment (ROI) calculator and regionally adapted guidelines to help alfalfa producers integrate cover crops and grazing while reducing weed pressure and input costs. Results from this project will be actively disseminated to alfalfa growers, industry representatives, researchers, students, and other stakeholders through a range of extension and outreach activities. These will include on-farm field days, workshops, extension publications, and presentations at scientific conferences and seminars to ensure the broad adoption and practical application of the findings.

This project directly aligns with Western SARE priorities by promoting economically viable, environmentally sound, and socially responsible agricultural systems. By integrating cover crops with grazing, the project addresses multiple sustainability goals simultaneously, reducing reliance on herbicides and synthetic fertilizers, improving soil health and nutrient cycling, increasing farm profitability through forage production, and strengthening collaboration between crop and livestock producers in organic and conventional production systems.

Research Objectives:

1. Weed Suppression and Community Dynamics: Quantify the effect of fall-planted berseem clover (Trifolium alexandrinum) with and without managed grazing on field bindweed density, total weed biomass, and weed bank composition in organic and conventional systems.
2. Soil Health and Nitrogen Dynamics: Evaluate changes in key soil health indicators and quantify nitrogen credits associated with berseem clover and grazing integration.
3. Forage Value and System Productivity and Profitability: Determine the nutritive value of berseem clover and clover-based mixtures and document grazing utilization. Assess the subsequent impact on organic and conventional alfalfa (Medicago sativa) establishment, yield, and forage quality, and whole-farm economic viability and system productivity.

Educational Objectives:

1. Increase Knowledge and Skills-By August 2029, at least 70% of participating alfalfa producers, livestock operators, and agricultural professionals will demonstrate increased knowledge and practical skills related to establishing fall-planted berseem clover, implementing managed grazing, and interpreting soil health indicators, as measured through pre- and post-event surveys.
2. Expand Regional Outreach and Collaboration - Between 2026 and 2029, project outreach activities, including on-farm field days, webinars, workshops, and extension publications will reach at least 500 producers, livestock operators, agricultural professionals, and crop advisors across Oregon, Colorado, and Idaho, with at least 60% of participants reporting improved understanding and intention to adopt integrated crop-livestock systems.