November 25, 2005 | General


BioCycle November 2005, Vol. 46, No. 11, p. 49
In a project demonstrating methods of manure management, a Hennepin County, Minnesota, waste abatement program shows horse owners the benefits of composting.
Betsy Gilkerson

WHEN people think of Hennepin County, Minnesota, most envision densely populated Minneapolis and the surrounding inner-ring suburbs. However, the county also has pastoral countryside and over 2,000 horses in seven cities that allow livestock. As this area develops and farms turn into houses, it becomes more difficult for horse owners to properly manage manure. This rapidly developing area is dotted with many lakes and 15,000 wetlands that can be adversely impacted by mismanaged horse manure. As a result, the regional park district and the county are cooperating on a composting program.
Three Rivers Park District consists of 26,000 acres of park reserves, regional parks, trails and special use areas that annually provide outdoor opportunities for three million park visitors. One of the parks in this system is Gale Woods Farm, a 410-acre working educational farm located 30 miles west of Minneapolis. The mission of the farm is demonstrating the practices and culture of contemporary small-scale production farming, and promoting land stewardship through agriculture education.
Gale Woods Farm and Hennepin County’s Department of Environmental Services are partners in an innovative project that collects horse manure from local farms, composts it and educates horse owners and municipalities about the benefits of composting. Three Rivers Park District was awarded a grant through Hennepin County’s Public Entity Waste Abatement Incentive Fund. To increase waste abatement throughout the county, the Hennepin County Board of Commissioners established a Public Entity Waste Abatement Incentive Fund in the amount of $200,000 for supporting innovative waste reduction and recycling projects by public entities in Hennepin County. Grants are awarded annually through this fund.
The goals for this project are improving soil fertility at Gale Woods, demonstrating proper methods of manure management, and encouraging private industry, local government and landowners to take over the system of collection and composting when the project ends.
The project began by selecting a manure hauler and horse owners to participate. The hauler selected was already hauling horse manure in the area. It was not practical to purchase hauling equipment for the project. Horse owners were selected based on proximity to Gale Woods, number of horses, and the pollution potential of their current manure management practices. Eight farms with 100 horses joined the project. The farms range in size from two to 33 horses. As an incentive, the grant reimbursed each horse owner for 75 percent of the hauling fees the first year, and 25 percent of the fees will be reimbursed the second year.
At Gale Woods, manure storage occurs on sites with an adequate vegetative buffer to prevent surface or ground water nutrient loading. Additional ingredients for the compost recipe include: lake weeds harvested from a nearby lake, granular urea, and woodchips as a bulking agent. The compost is mixed using a manure spreader and managed three different ways: In an Ag Bag demonstration pod; Mixed windrows; and Static piles; A variety of methods were used to demonstrate the advantages and disadvantages of each. In September, a demonstration day was organized to display the project to area government officials and local horse owners. This event was well attended.
As with any project, unexpected challenges arise. One challenge was managing a larger volume of materials than anticipated. The farm took in roughly 3,000 yards of manure and bedding and on average it was comprised of approximately 70 percent pine shavings bedding and 30 percent manure. Pine shavings are popular and used in such large quantities because of their high absorbance, lack of dust, softness, clean smell and ease of clean up. As a result of this large quantity of bedding, approximately 1,000 yards of lake weed were used to create an appropriate C:N ratio and moisture level in the compost mixture. This overall quantity was approximately twice the volume of manure anticipated from 100 horses. Given the rolling terrain of the farm and the number of waterbodies on the farm, it was challenging to find appropriate areas suitable for composting this volume of material.
Another challenge for the park was providing adequate labor for maintaining the compost. The labor was provided largely from the park district maintenance crews. As with many park systems, there are always many projects going on in the summer. There were times when they just couldn’t get to the farm to manage the piles when needed.
Several findings have surfaced from the project so far. One is that the interest in having manure hauled is greatly affected by the price of hauling. There were many horse owners who were interested in a hauling service, but as the price increased, the interest level decreased. Also, some of the barns won’t have as much manure hauled out this year from this program due to the reduced level of reimbursement.
The experience in this project has also made people look more closely at alternative bedding types that may be more readily compostable. There are several products available such as wheat-based, straw-based, and pellets from pine or other organic materials. These all have smaller particle sizes, which will compost faster and reduce material volume. Further research is needed since compaction will become a problem with smaller particle size.
Another finding is that the end use of the compost plays a significant role in the management techniques and the ability to use a waste material such as horse manure. The high carbon levels prevent the creation of potting soil grade compost in the time allotted. It takes roughly two years to break down the shaving to a humus-like texture. The finished product, however, appears to work well for tilling into gardens and spreading on hayfields. As a primarily organic farm, Gale Woods has a need for this type of compost, so the composting itself was successful. As private or public entities look at starting a horse manure composting program, it will be necessary to know what kind of compost will be produced and how it will be used.
In the second year of the project, more work will be focused applying the findings of the project. As stated earlier, a major goal is having the project taken over by a local government or a private business. Many people are excited about the idea of composting sites and manure collection, but have not stepped up to provide the land, labor and equipment to realize the goal. However, with growing demand for compost in erosion control, landscaping and the organic farming industry, it is possible that either a public or a private interest could be successful at hauling manure and turning it into a value-added product.
There are two significant outcomes from this project so far. One is that high value compost cannot be created quickly using the inputs and methods from this project. Second, the utilization of horse manure is not fully explored yet and with careful planning, it has the possibility to change dramatically in the next several years as public and private sectors recognize the opportunities.
Betsy Gilkerson is a Hennepin County Agriculture Technical Advisor with the University of Minnesota Extension Service in Minneapolis.

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