Effect of Sewage Sludge on Nutrient and Toxic Metal Content of Soil and Selected Crops Grown on Tropical Soils

摘要

Application of municipal sewage sludge to agricultural land is one means of disposing of this material. In general, no important negative effects on either quality of fruit, grain, or forage was observed in the study involving two soil types (one Oxisol and one Vertisol) representing northwestern and southwestern Puerto Rico. Sorghum, pigeon pea (Vertisol site), and eggplant (Oxisol) were grown in field experiments using from 0 to 24 Mg/ha of aged Ponce municipal sludge. Yields were determined and leaf, fruit, grain, and soils were analyzed. Sludge tended to increase yields and increases in iron concentration in sorghum grain and zinc concentration in pigeon pea are seen as positive effects on quality. Nickel content increased in the leaf tissue of the sorghum while it decreased in the eggplant fruit tissue.