Management of organic amendments in vegetable crop production systems in Florida

Florida produced more than 20% of the nation's fresh vegetables with sales of more than $1.6 billion during 1997. Predominant soils for vegetable crop production in Florida have a sandy or gravelly texture with low organic ma tter contents. Soil organic amendments are usually in the form of animal ma nures, preen manures (cover crops), and composts. Composts, derived from va rious organic wastes, have become increasingly popular soil organic amendme nts. Research has demonstrated that compost can serve as a soil amendment t o increase organic matter, improve microbial activities in soil, provide nu trients, and ultimately improve plant growth and yield. However, composts a re produced from various organic wastes and consequently, environmental con cerns are always an issue in compost utilization. The potential often exist s for heavy metals to accumulate in the soil and sometimes in the edible pa rts of vegetable plants. Excessive nutrients or metals released from compos ts may be leached out of the root zone and into goundwater by irrigation or by rainfall. Other hazards such as human pathogens, viable weed seeds, and plant phytotoxicity should be considered when developing: vegetable produc tion systems with compost.