Comparative Analysis of Aerobic Composting of Fresh Cut Floral Waste

Abstract

Abstract Increased levels of pesticide applications are used when growing cut flowers in many developing countries where most are grown and where they are less restrictive on pesticide use when compared to regulations in the United States. Therefore, special consideration should be given to cut flower disposal from floral shops that utilize flowers from other countries due to the potential for pesticide leaching into land and waterways. Most retail florists in the industry dispose of their floral waste in municipal dumpsters. While the United States Department of Agriculture (USDA) has stringent guidelines to prevent the importation of insect and disease pests, there are no regulations regarding residual pesticides or other harmful chemical contamination on imported floral crops. Composting is one technique used as an alternative waste management method to traditional landfill dumping and can produce a valuable commodity for agricultural, horticultural, and related industries. The main objectives of this study were to compare the physicochemical properties of two different compost protocols that incorporated cut flower and foliage waste and to determine whether pesticide residues remained in the finished compost. Analysis of results were based on the U.S. Composting Council's Tests Methods for the Examination of Composting and Compost used by the U.S. Composting Council's Seal of Testing Approval (STA) program. When compared to STA standards, both compost samples pH, total nitrogen, C:N ratio, and bioassay were found to be within normal ranges for compost sold in the horticulture industry. Chemical analysis found the levels of arsenic, cadmium, copper, lead, mercury, molybdenum, nickel, selenium, zinc all to be well below set industry standards. Additionally, the compost was tested for 23 herbicides and insecticides. Of those, two herbicides (clopyralid and MCPA) and one insecticide (lufenuron) were found in the sample in trace amounts, though well below USDA standards for food crops after the composting process. Results indicated floral waste collected from retail flower shops has the potential to be incorporated into a composting system to create a quality compost suitable for use in the horticulture industry.