Washington State University-Puyallup Organic Farm conducts long-term research projects on a 4-hectare plot to compare how different organic farming systems affect the quality of the soil, nutrients, weeds, and yields of the crops, as well as to compare different types of soil amendments, cover crops, and tillage. Various vegetables are grown including squash, beans, broccoli, lettuce, and spinach. Experiments include projects with cover crops, canola (organic feed for cattle and oil for energy), sweet corn, a bamboo grove, and experiments with biosolids (derived from human waste that was made safe by treating with heat). Researchers at WSU Puyallup also work on nursery and greenhouse crops, berries, integrated pest management, water quality, and diseases of ornamental crops.