Tomatoes for processing were cultivated from March to August of 1980 at a farm-land in the reclaimed land of Nakanoumi, the surface soil of the farm-land having been improved by the addition of municipal sewage sludge in 1978. No appreciable acidification of the surface soil occurred during the experimental penod in a field to which a sufficient amount of the sludge had been added, and the yield of tomato fruits in the field was considerably higher than that in a field to which calcium carbonate had been added in the place of the sludge. The results of analyses of various chemical components in soil indicated that the addition of the sludge contributed not only to the retardation of soil acidification and the supply of phosphate but also to the multiphasic fertilization of soil. On the other hand, the yield of tomatoes markedly varied from one ridge to another, even when the ridges belonged to the same field in regard to soil improvement. The cause of the variation remained to be elucidated.