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Right: In this typical windrow operation, the average windrow is between 4 and 8 feet high and between 14 and 16 feet wide—large enough to generate sufficient heat and maintain temperatures, yet small enough to allow oxygen to passively flow to the windrow's core.Photos: Coker Composting and Consulting
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Compost used as a turf topdressing following core aeration brings nutrients and organic matter down to the root-zone of grasses, reducing the potential for diseases such as dollar spot, red thread, and brown patch.

Once finished, compost is both stable and mature. Stability is the extent of organic matter decomposition (a completely stable compost is 100% decomposed). Maturity is a measure of how complete the composting process is (an immature compost, while stable, may still contain some intermediate byproducts of decomposition that can be harmful to plants).

Compost's benefits to soils are physical, chemical, and biological. Physical benefits include improved soil structure (tilth) and improved moisture management (both higher moisture capacity and higher infiltration). Chemical benefits include increased available plant nutrients (compost is a slow-release, low-grade source of nutrients), improved cation exchange capacity (a measure of plant nutrient uptake efficiency), and pH buffering. Biological benefits are an improved and more diverse soil biota and increased resistance to root rot diseases. All three benefits add up to healthier soils, and consequently healthier plants. Long-time users of compost in professional landscape and turf management report reduced herbicide and pesticide usage.

Park managers can use compost in three ways: as a soil amendment when constructing of landscape beds and turf-grass areas, as a topdressing following annual core aeration of turfgrass, or as a mulch. Soil amendment uses the most compost. Application rates, depending on existing soil quality and desired organic matter levels, fall in the range of 3 to 6 cu. yds. per 1000 square feet.

Compost as turf topdressing following core aeration brings nutrients and organic matter down to the root zone of grasses and can significantly reduce potential diseases like dollar spot, red thread, and brown patch. Topdressing is applied about 1 to 1½ cu. yds. per 1000 square feet. Compost for topdressing must be dry enough to pass through a rotary or drop spreader and screened to ¼ inch or finer.

Parks and recreation managers have the opportunity to turn discarded waste material into a valuable horticultural product, not only improving the environmental sustainability of their organization, but also reducing operational costs. For more information, visit the U.S. Composting Council Web site at www.compostingcouncil.org.

— Craig Coker is on the board of directors of the U.S. Composting Council and is a principal in the firm of Coker Composting & Consulting in Roanoke, Va.