YARD TRIMMINGS DIVERSION
LESSONS LEARNED FROM ON-FARM COMPOSTING
Six farms compost municipal leaves, reaping benefits and providing insights on their experiences.

A.H. Christian, G.K. Evanylo and J.W. Pease

Virginia Tech and Virginia Cooperative Extension, the Rivanna Solid Waste Authority (RSWA) and the City of Charlottesville collaborated on a project to divert municipal yard trimmings to farms for composting and agricultural use. Funded by the USDA’s Sustainable Agriculture Research and Education initiative, the program provided technical assistance and economic assessment for farmers, conducted educational outreach, and developed several handbooks.

An Albemarle County, Virginia farm received approximately 1,610 cubic yards (cy) of leaves debagged by municipal workers at the farm. Five other farms each received 180 to 250 cy of leaves, making a total of about 2,600 cy for the six farms. All but one cocomposted the leaves with chicken or turkey litter delivered from nearby poultry operations.

Windrow construction was accomplished with a tractor and bucket and, in two cases, also with a manure spreader. The RSWA loaned its tractor-pulled Wildcat windrow turner to the farmers, four of whom utilized it for three to eight turnings. Additional turning and mixing was done with a tractor and attached bucket or fork.

OBSTACLES PROVIDE INSIGHT

Several challenges arose during the project. Delay of leaf delivery for five participants until the spring growing season, for example, made it difficult to tend to the windrows. Compost pad siting was problematic in a few cases due to rolling topography that made equipment access and maneuverability difficult. A much greater volume of leaves than initially planned was delivered to the farmer who received the 1,610 cubic yards. This resulted in the windrows stretching far beyond the original site into a swale, where the soil was often too wet for equipment traffic,

Initial construction of windrows with a manure spreader was effective only when small volumes of alternating individual feedstocks were added continuously or feedstocks were layered in the spreader before operation; otherwise, the resulting windrows included unmixed sections of single feedstocks. Remixing with a manure spreader is very effective, but it is more time consuming than utilizing a tractor with bucket or similar equipment.

Approximately six parts leaves to one part litter/manure was blended at each farm based on average C and N analyses of the feedstock; however, there were considerable differences in how the piles performed. In some cases, the windrows continued to heat for several weeks to temperatures greater than 60°C following daily or alternating day turnings. At other sites, temperatures rarely exceeded 50°C.

These differences illustrated the variability in feedstock characteristics and composting conditions. Variations in C:N ratio, moisture content and bulk density were inevitable among different litter sources. Litter was stockpiled uncovered for up to a month prior to windrow construction at some locations. Different ages of bedding meant variation in readily available nitrogen, and some composting mixes had greater proportions of bedding than others. The age and condition of delivered leaves also varied.

Watering windrows during turning was less of a critical practice than normally would be the case because there was more than sufficient rainfall during the spring. In fact, excess water supplied by snow and rain reduced the composting rate at most sites because farmers lacked the equipment, labor and/or time to adequately aerate the windrows. However, no objectionable odors were reported by participants or their neighbors.

An economic evaluation of the expenses of leaf delivery and composting was conducted by Virginia Tech Agricultural Economics faculty. The cost for labor, cocomposting materials, and equipment use (not including the windrow turner) ranged from $4.36 to $17.40/cy of finished material. The greatest expense was incurred at the farm that received 1,610 cy of leaves, largely because of the extensive windrow construction activities necessary to manage the inflow of many more leaves than originally planned. The city of Charlottesville paid an additional $1,970 in leaf hauling and debagging costs, but still found the arrangement attractive. Project expenses for the RSWA were about $2,000.

POSITIVE RESULTS

All of the participants are continuing to compost for on-farm use or sale of the finished material, and three are composting at the same level they did for the pilot project or greater. Composting with the windrow turner reduced processing time and produced a more desirable end product than simply turning with a bucket. Finished compost has been used in landscaping projects and vegetable production, bagged and sold from a nursery retail operation, and sold in bulk.

Participant Panorama Farms signed a five-year contract with Charlottesville to receive at least 1,000 tons of leaves annually. It purchased a tractor-pulled windrow turner and expects to process more than 3,000 cy of material this year.
A significant regulatory benefit also arose from the project. Coordinators worked closely with one of the senior environmental engineers in the Virginia Department of Environmental Quality to clarify the regulations concerning yard trimmings composting with agricultural manures. The agency’s interpretation of the regulations resulted in an encouragement of on-farm composting of manures with yard trimmings.

Four Cooperative Extension publications were produced, including a 36-page guidebook for farmers, Closing the Loop:

Public-Private Partnerships for On-Farm Composting of Yard Waste. The documents are available on the VCE website at www.ext.vt.edu/resources.

A.H. Christian, G.K. Evanylo, and J.W. Pease are with the Departments of Crop and Soil Environmental Sciences and Agriculture and Applied Economics, Virginia Polytechnic Institute and State University, Blacksburg.