Finding the irrigation threshold with cover crops and manure inputs: Soil health, nutrient cycling, and weed suppression in an organic grazed system

Commodities

Practices

Organic producers in irrigated and semi-arid regions depend heavily on cover crops, manure application, and grazing to maintain soil health. While organic agriculture provides wide benefits to environmental and human health, it often presents unique challenges in dryland ecosystems, especially escalating the challenges in soil moisture, nutrient management, and weed pressure. Despite these problems, limited on-farm research has evaluated irrigation levels and the impact of organic nutrients on soil physical and biological processes, nutrient cycling, coupled with weed pressure in grazed organic cover crop systems. In particular, Phosphorus (P) dynamics are underexplored, leaving producers with scarce guidance on nutrient management in cover-crop-managed systems under water-limited conditions. This on-farm producer-centric project will evaluate how irrigation levels and chicken manure inputs affect the cover crop performance, weed suppression, and soil physical and biological properties in the grazed cover crop system.

Treatments will include standard and reduced irrigation integrated with a five-species cover crop mixture with and without chicken manure. Measurements include cover crop biomass production, weed ground cover, with a focus on below-ground soil health indicators, including soil moisture, infiltration, and key phosphorus pools.

Research findings will be communicated to growers through field days, surveys, short educational videos, and extension fact sheets to effectively translate the findings into practical management decisions.

Anticipated outcomes include an advanced understanding of how irrigation management and chicken manure inputs affect soil structure, water retention, and P cycling, coupled with weed management. Therefore, this project will deliver practical approaches to soil health management in organic-grazed cover-cropping systems.

1. Evaluate the impact of irrigation and nutrient management on cover crop biomass production and weed suppression in grazed organic systems.
2. Identify the fate of phosphorus and soil health properties under varying irrigation and chicken manure levels.
3. Improve the decision-making process of organic growers during water-limited conditions through extension and outreach activities such as field days, factsheets, and articles on identifying optimum irrigation and nutrient levels.