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Soil enzyme activities and water stable aggregates have been identified as sensitive soil quality indicators, but few studies exist comparing those parameters within buffers, grazed pastures and row-crop systems. Our objective was to examine the effects of these land uses on the activities of selected enzymes (b-glucosidase, b-glucosaminidase, fluorescein diacetate (FDA) hydrolase, and dehydrogenase), proportion of water stable aggregates (WSA), soil organic carbon and total nitrogen content. Four management treatments [grazed pasture (GP), agroforestry buffer (AgB), grass buffer (GB) and row crop (RC)] were sampled in 2009 and 2010 at two depths (0 to 10-and 10 to 20-cm) and analyzed. Most of the soil quality indicators were significantly greater under perennial vegetation when compared to row crop treatments. Although there were numerical variations, soil quality response trends were consistent between years. The b-glucosaminidase activity increased slightly from 156 to 177 lg PNP g -1 dry soil while b-glucosidase activity slightly decreased from 248 to 237 lg PNP g -1 dry soil in GB treatment during 2 years. The surface (0-10 cm depth) had greater enzyme activities and WSA than sub-surface (10-20 cm) samples. WSA increased from 178 to 314 g kg -1 in row crop areas while all other treatments had similar values during the 2 year study. The treatment by depth interaction was significant (P \ 0.05) for b-glucosidase and b-glucosaminidase enzymes in 2009 and for dehydrogenase and b-glucosaminidase in 2010. Soil enzyme activities were significantly correlated with soil organic carbon content (r C 0.94, P \ 0.0001). This is important because soil enzyme activities and microbial biomass can be enhanced by perennial vegetation and thus improve several other soil quality parameters. These results also support the hypothesis that positive interactions among management practices, soil biota and subsequent environmental quality effects are of great agricultural and ecological importance.

In the search for alternative practices to chemical soil fumigation (CSF), anaerobic soil disinfestation (ASD) has proven to be a promising tool for soil-borne pest management and crop production improvement. The ASD treatment with composted poultry litter (CPL) and molasses (M, a labile carbon source) was identified as an effective approach for a biologically based soil disinfestation system in tomato (Solanum lycopersicum L.) production in Florida. However, environmental and food-safety concerns are associated with animal manure-based amendments, which led to the exploration of composted yard waste (CYW) as a potential substitute for CPL in ASD application. In this study, field trials were conducted in Citra and Immokalee, FL to examine the effects of ASD using CYW, CPL and M compared with a commercially available microbial amendment system on root-knot nematodes, weeds, fruit yield and quality of fresh-market tomato. Treatments included (1) ASD with CPL (11 Mg ha−1) and M (6.9 m3 ha−1) (ASD0.5), (2) ASD with CYW (26.9 Mg ha−1) and M (CYW1 + M), (3) ASD with CYW (13.5 Mg ha−1) and M (CYW0.5 + M), (4) Soil Symphony Amendment (SSA), (5) CYW (26.9 Mg ha−1) alone (CYW1) and (6) a combination of CYW1 + SSA, in comparison with (7) untreated control and (8) CSF (Pic-Clor 60 at 224 kg ha−1). Cumulative soil anaerobiosis was greater in ASD0.5 compared with all the other treatments. The root-knot nematode gall index ratings on the tomato crop were significantly lower in CSF, ASD0.5, CYW1 + M and CYW0.5 + M than untreated control in Citra. Although CYW1 and SSA alone had a moderately suppressive effect on weed coverage and root-knot nematodes, their positive impact on crop performance was limited when used alone. ASD0.5, CYW1 + M and CSF had significantly higher marketable and total fruit yields than untreated control in both locations, while all treatments showed promising results in the Immokalee trial in comparison with untreated control. In general, few differences in major fruit quality attributes were found. Although using CYW in ASD was not as effective as CPL in creating soil anaerobic conditions, the enhanced crop performance in CYW1 + M and CYW0.5 + M suggests the potential of using CYW as an alternative source of organic amendment in combination with M to achieve benefits similar to those obtained with CPL-based ASD.

Fusarium, Cylindrocarpon and Pythium spp. are the major soil-borne pathogens of conifer seedlings. Soil fumigation with methyl bromide and chloropicrin has been the most effective method for reducing the population density and disease pressure of these organisms. Due to safety and environmental concerns, use of methyl bromide as a pre-plant soil fumigant has been

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