Analysis of Water Quality Impact of Windrow Composting
Posted May 2018
This study investigates composting operations and applications on three Dane County dairy farms that are composting bedded pack manures from livestock housing where cornstalks, straw, wood shavings, and/or sand are spread on the floor for bedding. This solid manure is typically managed separately from the manure produced by lactating dairy cows, which often goes into liquid storage. Bedded pack manure can make up 20-25% of a dairy farm’s total manure production.
Composting is an ancient and cost-effective way to speed the decomposition of manure by piling it in rows and turning it regularly to aerate. For the last two years, three members of Yahara Pride Farms have been working with UW-Madison to determine whether composting can lead to reductions in phosphorus (P) runoff loads from their farms.
Our objective was to evaluate potential runoff P losses on these farms during the manure composting process, and to follow compost application to cropped fields and compare it to expected losses from applying the manures directly to the fields without composting. Secondary objectives were to document the agronomic benefits and costs associated with composting, and to evaluate the costs per pound of runoff P reduction.
This report was produced by Dr. Laura Ward Good, UW-Madison Department of Soil Science, and Pamela Porter, Center for Integrated Agricultural Systems, under contract with Clean Lakes Alliance, a nonprofit organization working to improve water quality in the Yahara River Watershed through funding from the Lake Michigan Federation.