Assessing Anaerobic Soil Disinfestation for Improving Weed and Soilborne Disease Management in High-tunnel and Open-field Salad Green Production

View the project final report

Commodities

• Vegetables: greens (leafy), greens (lettuces)

Practices

• Crop Production: high tunnels or hoop houses
• Pest Management: integrated pest management, physical control
• Production Systems: organic agriculture
• Soil Management: composting

Organic production of leafy greens in the U.S. has steadily increased over the past decade. Florida follows the national trend with organic production representing one of the fastest growing sectors in the agricultural industry. Despite increases in production and demand for salad greens, soilborne pathogens and weed management remain a critical issue for organic producers. Unlike conventional producers with access to chemical fumigants and herbicides, organic producers have limited options. One method showing great potential is anaerobic soil disinfestation (ASD). This preplant method involves addition of molasses and organic amendments, saturating the soil, and covering with gas-impermeable barrier to facilitate shifts in microbial communities and promote soil chemical changes harmful to soilborne pathogens and weed seed viability. However, adoption of ASD at a commercial level is hindered by lack of field-based recommendations regarding application timing and rate of organic soil amendments especially for baby-leaf salad greens. Based on inputs from organic growers, we propose the use of 6-mil silage tarp in ASD, which does not require specialized machinery, is able to be recycled over multiple seasons and can be implemented in high tunnel systems. The main goal of this 2-year project is to examine application timing and rate of ASD amendments in organic high-tunnel and open-field systems for developing recommendations on ASD application in production of direct seeded baby leafy greens. Project findings will contribute to improving ASD as an environmentally friendly method for soilborne disease and weed management and benefit both organic and conventional production systems.

With the long-term goal of developing cost-effective and environmental-friendly ASD application for improving baby leafy green production systems, the specific objectives of this project include:

Objective 1: Optimize application timing and rate of ASD amendments in high tunnel and open field for controlling weeds and soilborne diseases in the production of organic, direct-seeded leafy greens

Objective 2: Determine the effects of ASD on total microbial biomass and microbial community composition in the soil

Objective 3: Monitor seasonal variability of soil nitrogen as affected by ASD in relation to soil moisture and temperature

Objective 4: Assess marketable yield and quality of baby leafy greens as affected by ASD treatments.