Greenhouse Broccoli and Lettuce Growth Using Cocomposted Biosolids

The benefits of compost applications on various soil types were demonstrated in greenhouse studies. A compost prepared from yard waste feedstock cocomposted with biosolids at a 1:1 ratio was used to grow broccoli (Brassica oleracea botrytis, var. ‘Brigadeer’) and leaf lettuce (Lactuca sativa, var. ‘Lallorosa’) at 0, 15, 30, and 60 dry tons per acre (t/a). Surface soil from three dominant regional soil types (Arnold loamy sand, Goleta loam and Todos-Lodos clay loam) was used in plastic pots in the greenhouse studies.All rates of compost applications increased the height and dry weight of broccoli shoots and dry weight of lettuce shoots in the various soil textures tested. In loam and clay loam soil, optimal rates of compost applications were 30 to 60 t/a for broccoli 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 showed less phytotoxicity symptoms to higher compost loads than did lettuce, probably because of more tolerance to greater salt concentrations.