Use of Urban Sewage Sludge as Soil Amendment and its Influence on the Development of Tomato Plants

Abstract

Accumulation of waste represents a huge problem for the urban development. One possibility of useful application of such waste is its application in agriculture. Tomato is one of the most important horticulture plants in Spain and especially in the region of Valencia. The effect of urban sewage sludge on the vegetative growth of tomatoes was checked on four types of soils from the Valencian region in Eastern Spain. Young plants were grown during four months in two experimental conditions, a control only with local irrigation water, and a treatment in which sewage sludge was added to each pot at the beginning of the experiment and watered with the same water type. Composition of soils, irrigation water and sewage sludge were analyzed and vegetative parameters, such as total length, length of stems and branches, and biomass of roots, stems, branches and leaves were measured. Plants achieved better vegetative development in the presence of sewage sludge in the four types of soils. The positive effect of the sludge is due to its high content in organic matter which clearly improves the qualities of Mediterranean soils, which are generally very poor.