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 matter contents. Soil organic amendments are usually in the form of animal manures, preen manures (cover crops), and composts. Composts, derived from various organic wastes, have become increasingly popular soil organic amendments. Research has demonstrated that compost can serve as a soil amendment to increase organic matter, improve microbial activities in soil, provide nutrients, and ultimately improve plant growth and yield. However, composts are produced from various organic wastes and consequently, environmental concerns are always an issue in compost utilization. The potential often exists for heavy metals to accumulate in the soil and sometimes in the edible parts of vegetable plants. Excessive nutrients or metals released from composts 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 production systems with compost.