Optimizing Tarping and Cover Crop Management Practices to Enhance Soil Health and Vegetable Crop Performance

Commodities

Practices

Soil tarping (occultation) is the practice of placing opaque plastic sheets, usually silage tarps, on the soil surface to block light, warm the soil, and manage soil moisture. Organic vegetable growers are readily implementing soil tarping to terminate cover crops, manage weeds, and prepare beds for planting without tillage. Previous research suggests that tarping can support weed control and vegetable crop performance equivalent to, or better than, conventional tillage while preserving soil structure and water holding capacity. However, relatively little research-based information is available to understand short-term nitrogen cycling dynamics in tarping systems related to variation in baseline soil health status, cover crop residue quality, soil disturbance intensity or maturity of a no-till system, and tarping duration. The scant information available suggests that these parameters can each have significant effects on soil microbiology, nutrient cycling and availability to subsequent vegetable crops, thus influencing nutrient use efficiency, long-term soil health and the ultimate sustainability of tarping practices.

The primary goal of our project is to provide organic vegetable producers with targeted recommendations to optimize integrated cover crop and tarping systems for enhanced nutrient use efficiency, weed control and crop performance. By conducting trials at two Michigan State University research stations and on-farm in partnership with six small vegetable operations, our project will account for the range of agroecological conditions, grower experience and management contexts in which tarps are being implemented across the North Central Region (NCR). Over two field seasons, we will compare six unique treatments designed to represent real-world variation in cover crop composition and tarping duration as key variables driving soil health and fertility outcomes in tarping systems. Comprehensive measurement of cover crop biomass and residue quality, soil temperature and moisture, nitrogen cycling and availability, as well as weed control, vegetable yield and quality outcomes will increase understanding of how cover crop and tarping systems can be optimized to enhance sustainability. Pairing this participatory research with multi-modal outreach and evaluation in the form of surveys, partial budgets, extension programming and publications targeting the wider population of small vegetable growers in the NCR will increase its relevance and impact. Through our integrated research and extension approach, we expect to document meaningful outcomes related to farmers increasing their knowledge and adoption/optimization of integrated cover crop and tarping systems, enhancing the economic viability and ecological soundness of small, organic vegetable farms, as well as quality of life for farmers.

Objectives

1. Engage small, organic vegetable growers in participatory research and outreach to understand variability in tarping practices and identify strategies to optimize tarping for nutrient management and crop performance.
2. Quantify the effects of baseline soil health, cover crop residue quality and tarping duration on nitrogen cycling, weed management and crop performance in organic vegetables across a biophysical gradient useful to farmers in the NCR.
3. Develop targeted cover crop residue quality and tarping duration recommendations based on farm location, soil type, weather and management history, as well as farmer objectives/priorities.
4. Share findings and recommendations with organic vegetable growers, agriculture professionals, and researchers beyond the project team to increase adoption of sustainable tarping practices within the NCR.

Outcomes

• Researchers and farmers will increase their knowledge and awareness of best management practices for soil health and fertility in integrated cover crop and tarping systems. (Learning)
• Farmers will increase their adoption or optimization of integrated cover crop and tarping systems, enhancing the economic viability and agroecological soundness of small, organic vegetable farms, as well as quality of life for farmers. (Action)
• Enhanced sustainability of small, organic vegetable farms using cover crops and tarping will reduce the ecological impact of agriculture and increase the accessibility of healthy produce in local food systems for all stakeholders. (Condition)

Engaging researchers, extension and small, organic vegetable growers in participatory research and outreach will increase their knowledge and awareness of best management practices for soil health and fertility in integrated cover crop and tarping systems. Optimizing cover crop and tarping systems for specific farm contexts and nutrient, weed and crop management goals will mitigate negative impacts of this practice on nutrient use efficiency and farmer quality of life, and also offset those risks/costs with positive effects on profitability and ecological soundness. Sharing this information with other researchers and farmers through project outreach activities will expand our project's potential reach and impact. Enhanced sustainability of small, organic vegetable farms using cover crops and tarping will reduce the ecological impact of agriculture and increase the accessibility of healthy produce in local food systems for all stakeholders.