Soilborne pests are a major obstacle that must be overcome for the production of horticultural crops. Methyl bromide (MBr) was an effective preplanting soil broad-spectrum biocide, but its use has been banned due to its role in depleting the ozone layer. As a result, sustainable alternative methods for controlling soilborne pathogens and pests are needed. Nitrous oxide (N2 O) emissions are of concern in crop production due to the role of N2 O as a greenhouse gas. Agricultural lands are known sources for emission of N2 O into the atmosphere. Emissions are related to many environmental factors as well as fertilization and fumigation practices. This study evaluated the influence of different alternatives to MBr on N2 O emissions throughout a tomato production season in two locations representative of southern and northern Florida. We evaluated eight soil management practices, including (a) untreated controls; (b) chemical soil fumigation; (c) anaerobic soil disinfestation using molasses (M) + composted poultry litter and (d and e) M + composted yard waste (CYW, at two rates); (f) Soil Symphony Amendment (SSA), a commercially available mix of microbes and nutrients; (g) CYW alone; and (h) CYW + SSA. Nitrous oxide emissions were measured throughout the cropping season. Emissions were highest on the day of planting (Day 21), ranging from 213 to 1,878 μg m-2 h-1 , likely due to the release of N2 O that had accumulated under the totally impermeable film when it was punctured for planting. However, statistical significance varied between sites. Estimated cumulative emissions of N2 O throughout the production season ranged from 1.3 to 4.8 kg N2 O-N ha-1 .

Anaerobic soil disinfestation (ASD) is proposed as a pre-plant, non-chemical soil disinfestation technique to control several soilborne phytosanitary issues. Limited information is available on the impact of ASD on soil fertility, plant growth, and potential nutrient loss. The objectives of the current study were to evaluate the effects of ASD applied using composted poultry litter (CPL) and molasses as amendments, on soil redox potential, pH, temperature, soil nutrient content, plant biomass and nutrient accumulation, and nitrous oxide (N2O) emissions. A field study was conducted on fresh-market tomato (Solanum lycopersicum L.) at two sites, Immokalee and Citra, FL, comparing ASD applied using a mix of CPL at the rate of 22 Mg ha(-1) and two rates of molasses [13.9 (ASD1) and 27.7 m(3) ha(-1) (ASD2)] as a carbon-source to chemical soil fumigation (CSF). ASD treatment had a significant impact on soil redox potential, but did not affect soil pH or temperature. Soil treatment did not affect nitrous oxide emissions from intact polyethylene mulched beds at either location. Emissions ranged from 0 to 0.378 mu g m(-2) h(-1) and from 8.8 to 39.8 mu g m(-2) h(-1) in Immokalee and Citra, respectively. However, on day 21 after punching holes in the polyethylene film to transplant, N2O emissions ranged from 1.56 to 4.83 and from 303.4 to 1480.1 mu g m(-2) h(-1) in Immokalee and Citra, respectively. Emissions were higher in ASD than in CSF plots in Citra, but not in Immokalee. Molasses and CPL used in ASD treatments increased soil nutrients content, and particularly the availability of P and K. Results show no clear evidence of an increased risk of N loss with ASD compared to CSF. However, pre- and post-planting nutrient management should be adjusted to take into account the nutrients provided through the molasses and CLP application. (C) 2017 Elsevier B.V. All rights reserved.