LONG TERM LARGE SCALE SOIL SOLARIZATION AS A LOW-INPUT PRODUCTION SYSTEM FOR FLORIDA VEGETABLES

Profound changes will occur from the loss of methyl bromide by the vegetable industry, since it is a key component in production systems. Many growers have relied only on methyl bromide to manage soil pathogens, nematodes, and weeds. This system combined with raised beds, plastic mulch, and drip irrigation has been very effective to produce high vegetable yields. Non-chemical alternatives like solarization and organic amendments are as yet largely unproven but do offer promise of sustainable solutions free of government regulation. The objective of this research was to study the effects of long-term, large-scale use of sustainable methods utilizing soil solarization and organic amendments on weed populations, nematodes, yields and soil fertility on peppers (Capsicum annuum L.) and cucumbers (Cucumis sativus L.). The field experiment was conducted during 1998 and 1999 season in a commercial vegetable farm in Boynton Beach, FL. There were five large plots consisting of 10 beds, 610 m long (1.3 ha). Treatments consisted of: 3 years of soil solarization and organic amendment; 2 years of soil solarization and organic amendment; 2 years of soil solarization and non-organic amendment; and methyl bromide as a control. At the end of the second crop, solarized treatments had higher % weed cover and were populated primally by bermudagras (Cynodon dactylon L. Pers.) a warm weather spreading perennial weed as compared with the methyl bromide production system, dominated by redroot pigweed (Amaranthus retroflexus L.) an annual weed easier to control than bermudagrass illustrating, a weak point of a long term solarization system. Population levels of the root-knot nematode [Meloidogyne incognita (kofoid and white) chitwood] fluctuated throughout the experiment. During 1999 and 2000, the lowest numbers occurred in the conventional system with methyl bromide. However on each sampling date, numbers in at least one of the sustainable systems were statistically similar to those in the methyl bromide-treated plots. Marketable yields of peppers appeared to be similar within the production systems for the 1998-1999 season. On all testing dates, organic matter, pH, and Mehlich 1-extractable P, K, Ca, Mg, and Zn were higher in systems where compost was applied than in systems without compost. Manganese was not affected, and Cu and Fe varied by year. The results suggest that large-scale soil solarization and organic amendment can be an attractive alternative to methyl bromide. However, methyl bromide produce the more consistent results.