Summary and Implications
A university-wide compost facility adjacent to the new dairy farm on 260th Street, about 2 miles south of campus, was planned, built, and brought through start-up into full operation during 2008–2009. The facility is managed by the College of Agriculture and Life Sciences’ Research Farms unit and has a separate revolving account that will receive all fees and sales and pay all expenses. The facility is designed to be self-supporting, i.e. not receive allocations for its operations.
Hoop barns cover the composting and receiving areas to control runoff and moisture content. A pull-type turner is used to maximize flexibility and minimize start-up costs. The hoop barns have paved floors to support the turner, and a scale is used to weigh all materials. The machinery includes: a turner, manure spreader, telehandler, and a tractor. The facility consists of seven, 80 x 140 ft hoop barns with paved floors. The central hoop barn is the receiving hoop and the other six are composting hoops. Using the current pull-type turner, there are three windrows per hoop.
The compost blend targets are a Carbon: Nitrogen ratio of 25-30:1 and a moisture of 45–50%. Other parameters to consider are porosity and structure. Porosity and structure both affect how well oxygen flows into the pile and its availability to the microbes.
In the first 11 months of operation, the facility has received approximately 8,056 tons of materials or about 732 tons/month. About 85% of the materials come from the dairy farm as various forms of manure—manure pack, solids from the separator, and general manure scrapings. The remaining 15% of incoming materials are as follows: 7% campus yard and greenhouse wastes, 6% manure from other ISU livestock farms, and 2% from a variety of sources, primarily ISU Dining food waste. The ISU Dining food waste stream started in August 2009 and is about 40 tons per month when classes are in session.
A projected annual incoming flow of material will be 10,000 tons. The breakdown is expected to be about 75% dairy manure, 5% other manure, 5% campus and greenhouse waste, 10% biomass research waste and 5% dining waste.
The compost is primarily used as a soil amendment or as a component of amended soil for university construction projects. The amended soil is made by mixing topsoil, compost, and sand. Most amended soil has been 3 parts topsoil, 2 parts compost, and 1 part sand; although a 1 part topsoil, 2 parts compost, and 1 part sand mix is also used. Construction projects at Jack Trice Stadium, BioCentury Research Farm, College of Veterinary Medicine, College of Design Pavilion, and BioRenewables Lab have used amended soil. The new "green" roof on the Design Pavilion is planted in amended soil from the University Compost Facility.
The average analysis of the compost produced in the fall was 26% moisture, 83% organic matter, and 9-7-9 lb/ton of total N-P205 and K20. Ammonia nitrogen was 6 to 13% of total nitrogen. The three samples were similar in fall 2008 and 2009.
A spring 2009 compost was much wetter–50% moisture, 71% organic matter, and 9-6-11 lb/ton of total NP205 and K20. More mature compost was drier (22 vs. 30% moisture), had more organic matter (83 vs. 79%), and slightly lower nutrient contents (10-5-9 vs. 11-7-13). Because the facility is so new, sampling and compost analysis will continue.
Iowa State University
Honeyman, Mark S.; Goode, Tim; Jonas, Steve; Huss, Mark; and Arora, Kapil
"A University-Wide Compost Facility: Start-Up and Operation,"
Animal Industry Report:
AS 656, ASL R2528.
Available at: http://lib.dr.iastate.edu/ans_air/vol656/iss1/49