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Monica Ozores-Hampton*

The success of long-term vegetable production and maintenance of environmental quality is dependent on soil quality. Indicators of soil quality include cation exchange capacity (CEC), organic matter (OM), carbon (C), pH, and the number and community structure of soil organisms. The use of appropriate compost has been shown to improve soil quality and enhance the response to fertilizer, therefore improving growth and yield of vegetable crops. The objective of this study was to evaluate changes in the chemical and biological properties of soil in response to compost use in conventional vegetables production systems. A survey was conducted on 5 farms (three in Immokalee, and one each in Delray Beach, and Clewiston) growing tomato, pepper, and specialty vegetables. Most of the farms were applying composted yard trimming waste alone or in combination with biosolids or horse manure at application rates of between 7 to 112 Mg·ha-1 once a year. Soil samples were taken from composted and non-composted areas in each farm during Feb. and Mar. 2002. Soil pH, OM, C, K, Ca, Mg, Cu, Fe, MN and Zn were higher in the composted areas compared with the non-composted areas for each farm. CEC values in composted areas were double those in non-composted areas. Most importantly, application of compost enhanced the overall soil microbial activity as determined by total microorganism number, SRD (species richness diversity), and TSRD (total species richness diversity) of six functional groups including heterotrophic aerobic bacteria, anaerobic bacteria, fungi, actinomycetes, pseudomonads, and nitrogen-fixing bacteria, in all the participating farms. The greatest soil quality improvement was seen in soils receiving the highest rates of compost for the longest time.

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Monica Ozores-Hampton

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Monica Ozores-Hampton

Compost is primarily a soil-amending product that may improve soil quality and the productivity of organic and conventional vegetable crops. Growers can use compost as a soil conditioner or as nutrient source to supplement the fertility program in vegetable production. Nutrients such as nitrogen, phosphorous, and potassium may be low. To lower the environmental impact of high compost application rates and protect water supplies from excessive nutrient runoff or leaching, or an excessive soil nutrient buildup, compost should be applied to match the nutrient needs of a crop. Compost quality use guidelines for assessing compost quality for use in vegetable production are limited. The objective of this paper is to present guidelines for determining compost quality for use in organic or conventional vegetable production.

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Monica Ozores-Hampton

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Monica Ozores-Hampton

A rapid increase in municipal solid waste (MSW) production (2 kg/person per day), combined with a decreasing number of operating landfills, has increased waste disposal costs. Composting MSW can be an alternative method of waste disposal to traditional landfilling or incineration. Weed control methods using waste materials such as bark, straw, and sawdust were used in commercial crop production for many years before the advent of chemical weed control. Weed growth suppression by mulching can often be almost as effective as conventional herbicides. A 10 to 15 cm-deep mulch layer is needed to completely discourage weed growth in these systems, and best results are obtained with composted materials. In recent years, composts made from a large variety of waste materials have become available on a commercial scale. Preliminary investigations into the use of MSW compost as a weed control agent have shown that compost, especially in an immature state, applied to row crop middles reduced weed growth due to its high concentration of acetic, propionic, and butyric acids. Subsequently, compost can be incorporated into the soil for the following growing season to potentially improve soil physical and chemical properties. Integrated pest management programs that incorporate biological control should be adopted wherever possible because some weed species with persistent seeds can escape chemical control.

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Monica Ozores-Hampton

Iron (Fe) deficiency is a frequent nutritional problem in Florida vegetable crops because of leaching of Fe fertilizer from the soil, poor soil aeration, low soil organic matter (SOM), temperature, high soil pH and/or water bicarbonate content, and interactions with high levels of manganese (Mn) and calcium (Ca). Most Fe-deficient plants are yellow and stunted, with symptoms on younger leaves near the top of the plant because of Fe immobility and poor translocation resulting in interveinal chlorosis. Iron deficiency in tomato (Solanum lycopersicum) is characterized by a drastic reduction of leaf chlorophyll content at first at the base of the leaves (bleached leaf) ending in necrotic spots. Iron deficiency can have a significant economic impact depending on the timing of the deficiency during the crop production cycle. Furthermore, crop genotypic variations influence the ability of root systems to acquire Fe. The objective of this article was to describe current methods used by vegetable growers to correct Fe deficiency and to evaluate their effectiveness in tomato, pepper (Capsicum annuum), bean (Phaseolus vulgaris), and eggplant (Solanum melongena) production in Florida. A survey was conducted in the major vegetable production areas in Florida during 2012. Results from the survey indicated that since Fe availability depends on complex soil and environmental factors, there was no reliable soil test method that can predict Fe deficiency on vegetable crops in Florida. Production areas surveyed with calcareous or alkaline soils that are often due to over-liming, Fe becomes unavailable because of significant reduction of Fe. Production practices for those areas were not to use calcitic lime to raise Ca levels, especially if the pH is adequate (6.5). Instead, gypsum or calcium nitrate was recommended for soil Ca. The survey indicated that Fe sulfate (inorganic form) is the most commonly used Fe fertilizer in Florida. However, chelates of Fe were effective but expensive Fe alternative. Among chelate sources, ferric ethylenediaminediaminedi-o-hydroxyphenylacetic acid was frequently the preferred chelate fertilizer for soil application, but it is an expensive option. Soil acidification to lower the soil pH was also used to improve soil Fe availability. Organic matter in animal manures and composts was used as an effective alternative to increase Fe with positive results in Florida tomato production. However, the survey indicated that Fe applied to the soil was converted into unavailable forms especially under high soil pH, thus foliar application was used if Fe deficiency symptoms were observed early in the production cycle.

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Monica Ozores-Hampton

This review integrates information from common organic amendments used in conventional vegetable production, including 1) cover crops (legumes and nonlegumes), 2) compost generated from yard wastes, biosolids, municipal solid waste (MSW), animal manures, and other biodegradable waste by-products, and 3) raw animal manure (with and without bedding). Environmental monitoring has shown elevated nitrate concentration to be widespread in both surface and groundwater, often occurring in regions with concentrated horticultural production. Therefore, the objective of this review was to calculate the nutrient content from organic amendments, since these are not considered nutrient sources. Common organic amendments affect soil bulk density, water-holding capacity, soil structure, soil carbon content, macro- and micronutrients, pH, soluble salts, cation exchange capacity (CEC), and biological properties (microbial biomass). The first step in building a conventional tomato (Solanum lycopersicum) fertility program will be to take a soil sample and send it to a soil laboratory for a nutrient analysis. These results should be compared with the local crop recommendations. Second, select the organic amendments based on local cover crop suitability and availability of compost, raw animal manure, or both. Then, determine the nutrients available from cover crops and other applied organic amendments and use inorganic fertilizer sources to satisfy the crop nutrient requirements not supplied from these other sources.

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Joan Bradshaw and Monica Ozores-Hampton

In 1988, the Florida Legislature passed the Solid Waste Management Act that affected the solid waste disposal practices of every county in the state. With legislation directly affecting the industry, organic recyclers and Florida Department of Environmental Protection (FDEP) regulators recognized a need to establish a professional organization that could serve as a unified industry voice, and foster high standards and ethics in the business of recycling and reuse of organic materials. In December 1994, a meeting was held to discuss the formulation of a Florida organic recycling association which became known as the Florida Organics Recyclers Association (FORA). FORA's first major contribution to the industry was the development of a recycling best management practice manual for yard trash in 1996. The second major project undertaken by FORA was a food waste diversion project which sought to promote an increase in food waste recovery and reuse. In Spring 1999, FORA became the organic division of Recycling Florida Today (RFT) further unifying recycling efforts within the State of Florida. In an attempt to address mounting concerns regarding industry marketing and promotional needs, RFT/FORA developed an organic recycling facility directory for the State of Florida in Spring 2000. Most recently RFT/FORA developed an organic recycling facility operator training course outline to assist the FDEP in identifying industry training needs. From its modest beginnings in 1994, to future joint programming efforts with the University of Florida's Florida Organic Recycling Center for Excellence (FORCE), RFT/FORA continues to emerge as a viable conduit of educational information for public and private agencies relative to organic recycling in Florida.

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Mike Litvany and Monica Ozores-Hampton

Commercial citrus (Citrus sp.) groves in Florida use an average of 150 lb/acre (168 kg·ha-1) of elemental nitrogen (N) per year. There are about 853,000 acres (345,000 ha) of commercial citrus requiring about 63,975 tons (62,652 t) of N. At an average analysis of 12% N, about 533,125 tons (483,811 t) of blended nitrogenous fertilizers are applied to citrus annually. To meet this annual N demand from compost, it would be necessary to produce 3,198,750 tons (2,901,906 t) of 2% N compost. The market for high-quality compost products in Florida is far greater than the current or projected production capacity of the state. As long as the cost benefits of compost are clear to citrus growers, demand will always exceed supply. Not all composts are equal in their nutrient availability. The best composts for use as fertilizers are derived from sewage sludge or biosolids, municipal solid waste and sludge, food waste, and/or animal manure combined with a bulking agent such as sawdust or wood chips. Composts made from wood waste as their only feedstock contain large amounts of lignin and cellulose to break down within a reasonable period to directly offset chemical fertilizers. Ultimately, they will mineralize in the soil and provide all of the benefits described earlier, but their rates of availability are in years rather than months, like the other composts.