Project Number: 8042-12630-006-00
Start Date: Apr 03, 2010
End Date: Apr 02, 2015
Modern livestock production involves the use of large amounts of nutrient inputs as well as antibiotics. Untreated manure is either stored or immediately applied to farmland as a fertilizer. When manure is applied to fields, manure components (nutrients, microorganisms, and remaining antibiotic residues) may reach surface water by volatilization, run-off or leaching. The goal of this research is to improve our basic understanding of two common manure treatment practices (composting and anaerobic digestion) so as to maximize their benefits and minimize their economic and environmental costs. The first objective is to evaluate the efficacy of a series of minimal management options for composting manure and poultry litter on-farm to reduce concentrations of ten widely used pharmaceutically active compounds. Treatments are designed to span a range of practical management options – from the current practice of stockpiling the manure/litter to amending it with straw (to increase aeration) and adding insulating layers of straw. The second objective seeks to reduce the environmental footprint of composting by reducing methane, nitrous oxide, and ammonia emissions during composting. Greenhouse gas and ammonia emissions will be measured using replicate pilot-scale compost piles composed of manure/bedding from the BARC dairy and food/green wastes from local food processors. The first set of treatments will test the timing and frequency of compost mixing and turning. Subsequent experiments will measure and compare gas emissions from replicate piles constructed at initial bulk densities and from piles covered with 7-30 cm layers of finished compost. The third objective involves an evaluation of a relatively low-cost anaerobic digestion system that has significant potential for use on small farms. Six replicate pilot-scale plug-flow digesters, with two operational designs will be studied to provide long-term research on a system that has not been fully explored. Treatment efficiency, capital and operational costs, and gas utilization strategies will be evaluated for each type of system. Costs and benefits of different treatment strategies will be compared to existing manure management practices.