DOMESTIC, EXOTIC, AND EMERGING DISEASES OF CITRUS, VEGETABLES, AND ORNAMENTALS (DEED)
Location: Subtropical Plant Pathology Research
Title: Exploring cover crops as carbon sources for anaerobic soil disinfestation in a vegetable production system
Submitted to: Soil Science Society of America Journal
Publication Type: Abstract Only
Publication Acceptance Date: October 11, 2011
Publication Date: November 6, 2010
Citation: Butler, D.M., Rosskopf, E.N., Burelle, N.K., Albano, J.P., Muramoto, J. 2010. Exploring cover crops as carbon sources for anaerobic soil disinfestation in a vegetable production system. Soil Science Society of America Journal.
In a raised-bed plasticulture vegetable production system utilizing anaerobic soil disinfestation (ASD) in Florida field trials, pathogen, weed, and parasitic nematode control was equivalent to or better than the methyl bromide control. Molasses was used as the labile carbon source to stimulate microbially-driven anaerobic soil conditions. Warm-season cover crops can fill a summer-fallow niche in Florida vegetable production systems, which can have agronomic and environmental benefits. These cover crops can subsequently serve as an on-farm carbon source for ASD. To test whether cover crops could replace molasses in ASD, a greenhouse trial was conducted using field soil in which warm-season legumes and grasses were grown and incorporated with or without composted broiler litter. Pots were then irrigated to fill porosity, allowed to drain, and covered with a clear plastic film to initiate a 3-week ASD treatment prior to planting tomatoes. Soil anaerobicity (Eh) was monitored during treatment and soil fertility assessed throughout the experiment. In nearly all cases, ASD treatment utilizing cover crops resulted in cumulative Eh values that were equal to ASD treatment with molasses and greater than a fallow control without added carbon source. Immediately following ASD treatment, soil inorganic nitrogen in all treatments was primarily comprised of NH4-N (85 to 97%) rather than NO3-N, and was greatest in pots where a legume cover crop (sunn hemp or cowpeas) was grown and/or composted litter applied. Throughout the study, germination of yellow nutsedge tubers introduced at treatment was highest from control pots without added carbon (75% tuber germination), lowest when molasses applied (8% tuber germination), and intermediate from cover crop treatments (41 to 64% tuber germination). The number and weight of tomatoes harvested and height and weight of tomato plants did not differ among ASD treatments. These results suggest that cover crops can be effective carbon sources for ASD.