GREENHOUSE BROCCOLI AND LETTUCE GROWTH USING COCOMPOSTED BIOSOLIDS

The benefits of compost applications on various soil types were demons trated in greenhouse studies. A compost prepared from yard waste feeds tock cocomposted with biosolids at a 1:1 ratio was used to grow brocco li (Brassica oleracea botrytis, var. 'Brigadeer') and leaf lettuce (La ctuca sativa, var. 'Lallorosa') at 0, 15, 30, and 60 dry tons per acre (t/a). Surface soil from three dominant regional soil types (Arnold l oamy sand, Goleta loam and Todos-Lodos day loam) was used in plastic p ots in the greenhouse studies. All rates of compost applications incre ased the height and dry weight of broccoli shoots and dry weight of le ttuce shoots in the various soil textures tested. In loam and clay loa m soil, optimal rates of compost applications were 30 to 60 t/a for br occoli and 15 to 30 t/a for lettuce. In loamy sand soil, optimal rates for broccoli and lettuce were 30 and 15 t/a, respectively. Broccoli s howed less phytotoxicity symptoms to higher compost loads than did let tuce, probably because of more tolerance to greater salt concentration s.