On-farm Evaluation of an Innovative Anaerobic Soil Disinfestation Practice for Improving Organic Carrot Production in North Florida

View the project final report

Commodities

• Vegetables: carrots

Practices

• Crop Production: nutrient management, organic fertilizers
• Education and Training: on-farm/ranch research
• Pest Management: biofumigation, mulches - general
• Production Systems: organic agriculture, transitioning to organic
• Soil Management: soil quality/health

This on-farm research project is a response to growers’ interest in seeking innovative solutions to overcome weed and disease management challenges in organic carrot production systems. Anaerobic soil disinfestation (ASD) as a non-chemical tool for controlling soilborne diseases and weeds also has great potential to enhance soil fertility and biological activity through the addition of organic amendments. However, the cost of implementing ASD treatments in commercial production is often perceived as an economic barrier for the wide-spread adoption among growers. To address cost concerns from the grower, we used locally sourced labile carbon amendments and re-usable 6-mil silage tarp for ASD application, which helps reduce waste from using single-season plastic covers. By teaching the grower how to implement ASD treatment utilizing locally available resources and re-usable tarp, we expect to establish a partnership with local growers for technology and knowledge transfer which allows for a practical assessment of ASD for improving high-value vegetable production systems. Results from a series of on-farm trials conducted at Siembra Farm in Gainesville, FL demonstrated promising effects of ASD application on managing weeds and enhancing carrot yields while maintaining or improving produce quality. The ASD treatment using Nature Safe organic fertilizer (10%N-2%P₂O₅-8%K₂O) at a rate of 175 lb N/acre + black strap molasses at a rate of 741 gal/acre + on-farm compost at a rate of 7.5 bu/100 ft² (ASD1) significantly reduced the number of weeds in the carrot field compared to grower’s practice using organic fertilizer applied at a rate of 130 lb N/acre + on-farm compost at a rate of 7.5 bu/100 ft² (Control) and the other two ASD treatments, i.e., organic fertilizer at 130 lb N/acre + molasses at 741 gal/acre + compost at 7.5 bu/100 ft² (ASD2) and organic fertilizer at 175 lb N/acre + molasses at 741 gal/acre (ASD3). Among the three ASD treatments, ASD3 led to significantly more marketable carrots than ASD1 and ASD2 by 33% and 34%, respectively. ASD3 also showed a numerical increase in marketable number of carrots relative to Control by 20%. Carrot quality assessment revealed significantly higher soluble solids content and total phenolic content in ASD3 vs. Control by 13% and 20%, respectively. The disease pressure including the nematode infestation level remained low throughout the carrot trials, with no ASD treatment effect observed. We demonstrated ASD treatment setup and presented research findings at the on-farm field day upon completion of the field trials. While more studies are needed to further improve on-farm ASD application and its effectiveness, this on-farm research project successfully introduced ASD as a biological management tool for enhancing organic vegetable production to growers and Extension agents. 

The specific objectives of this project include:

Objective 1: Develop ASD treatments based on farmer-recommended inputs that fit within the site-specific farming system.

Objective 2: Determine the effectiveness of ASD for controlling weeds and soilborne diseases in the production of organic, direct-seeded carrots.

Objective 3: Assess marketable yield and carrot quality as affected by ASD treatments.