In June 2007, Soil Key organized an IASP biosolids composting pilot study in Tenino, Washington. Biosolids are the organic residuals produced during wastewater treatment. Once composted, biosolids look like other commercially available composts and are approved for use by the U.S. Environmental Protection Agency as a soil amendment by home gardeners, farmers and others. Biosolids provide soils with the nutrients that tend to be deficient. These products are used in landscaping and gardening in the following ways:

• As a fertilizer: Biosolids products help plants by adding nitrogen, phosphorus and other nutrients to soils.

• As a mulch: The addition of biosolids compost as a mulch reduces watering requirements and prevents weeds.

• As a potting medium: When mixed with potting soil, biosolids products provide an ideal medium for potted plants and greenhouse containers.