Abstract
Waste water disposal by irrigation onto arable land provides water purification before the water is returned to the natural reservoirs and recycling of nutrients. Comparisons were made of a cambisol supplied with waste water since 1900 and a similar soil from under a pine forest with no application of waste water. Parameters examined in each soil were total porosity, pore size distribution, hydraulic conductivity, nitrogen forms, exchangeable ions, and heavy metals. No great differences were noted in texture and bulk density of the two soils. Long-term waste water irrigation of the cambisol caused a slightly increased organic content as well as higher levels of phosphorus and nitrogen. Copper and zinc were also highly retained by the cambisol when compared to the forest soil. Manganese and zinc were lost in the subsoil of the cambisol due to low oxidation potentials. Both sites underwent changes in elemental content due to intense air pollution and the effects of rainfall. Changes in soil content of elements were calculated by a mathematical formula based on soil horizon data. The dynamics of flooding and drainage at the two sites and their effects on soil composition were also investigated. Results of these studies indicate sharp reductions in the filtering of iron and manganese nutrients. (Geiger-FRC)