Community manure management addresses manure storage, processing, and by-product generation at a multi-farm or community scale. The goals of community manure management are to:
Dane County has been exploring ways to assist the agricultural industry by supporting a variety of community manure management pilot projects including manure digesters, nutrient concentration systems, and manure composting.
Dane County led the development of two community manure digesters based on recommendations from the Community Manure Feasibility Study Committee to improve water quality. The primary goal of the digesters is to reduce phosphorous in water runoff from surrounding farm fields by removing it from manure. There are currently two community digesters, one north of the Village of Waunakee and the other near the City of Middleton in the Town of Springfield.
In 2010 Dane County commissioned its first community manure digester located just north of the Village of Waunakee. The digester serves a centralized collection and processing facility for 35 million gallons of manure generated from three nearby farms annually. The manure is pumped from the farms into three 1.25 million gallon digester tanks where it undergoes anerobic digestion. After digestion, fiber and solids containing large amounts of phosphorus are removed through a combination of centrifuges and screw presses. These solids can then be used for bedding or as a fertilizer and soil amendment for area cropland. Liquid, from the solids separation process, containing nitrogen and potassium is then returned to participating farms where it can also be utilized as a fertilizer for growing crops.
Another by-product of the manure digester process is the generation of methane gas during anaerobic digestion in the three digester tanks. The gas is collected, cleaned, and transported to the Dane County Landfill where it is sold and injected into the Interstate Pipeline to be distributed throughout the United States as natural gas for home and industry use.
The second digester, located northwest of the City of Middleton, was commissioned in 2013 and collects manure from three near-by farms. In this model, two farms use semi-trucks to transport manure to and from the facility while the third farm is located close enough to the facility to pump manure. More than 26 million gallons of manure is processed at the facility each year using similar screw press and centrifuge technology to separate fiber and solids containing phosphorus as the Waunakee community digester. This facility has the ability to generate over 2,000 kW of electricity by processing the methane gas generated directing into electricity.
This location also includes a 71,000 square foot building and turner for composting the separated solids as well as a 15 million gallon manure storage facility to store the separated liquids. The addition of on-site storage provides greater flexibility in accommodating emergency situations from area farmers. The facility is also designed to accommodate further treatment technology including nutrient concentration systems.
June of 2020 marked the completion of additional manure treatment and commissioning of Dane Counties first Nutrient Concentration System. Manure that has been processed by the Middleton digester and undergone solids separation is pumped through ultrafiltration and reverse osmosis membranes, oxygenated and adjusted for pH, before being discharged to the North Fork of Pheasant Branch Creek. The system has the capacity to treat up to 100,000 gallons of manure each day while returning as much as 50,000 gallons of clean water back to the stream.
In addition to returning clean water to the environment, the system also provides the following benefits:
Composting is not a new concept; it is a naturally occurring process in the environment in which organic material and nutrients get recycled back into the soil. From an agricultural perspective, the practice has been documented going back thousands of years to prehistoric farming people and was commonly used up until the twentieth century when synthetic fertilizers were introduced in order to increase food production for a growing population. However, synthetic fertilizers do not provide the same soil conditioning benefits that compost does. With an increased focus on soil health as well as a desire to manage nutrients such as phosphorus, composting is coming back as a low technology (though high management) alternative to managing manure while benefiting the soil and reducing nutrient runoff. The major difference between composting during prehistoric times and today is the scale of agriculture. To make composting work for farms today requires innovation and partnerships.
Over the past few years, Dane County has supported the efforts of Yahara Pride Farms and Endres Berryridge Farms to explore composting as a manure management tool by supporting the purchase of a compost turner and compost spreader to be used in the Mendota Watershed.
The benefits of composting manure and having the right equipment include: