The following figure describes the effect of compost on microbial activity. Four composts were added to each field at 30T/A, except vermicompost at 5T/Ac, and measured two weeks after incorporation. Five field sites were evaluated, three on the central coast and two in the Sacramento valley. Hydrolysis of fluorescein diacetate were used to measure microbial activity. MB, methyl bromide fumigated field; Conv., conventionally managed field; Org, organically managed field.