Long term effects of excessive organic waste application

摘要

The change of soil properties, crop yields and crop contents from the last seven years of a field experiment, started in 1976, with high amounts of sewage sludge and pig slurry application (2 and 5 tons of organic matter per hectare and year) are discussed. Levels of zinc and cadmium reached or even exceeded actual limits of Swiss legislation. We observed that the essential elements (copper and zinc) are mainly concentrated in the generative parts (grain), whereas cadmium is mainly found in the vegetative parts (straw, leaves) of the plant. A lowering of the soil pH-value by a few tenths increased the solubility of the heavy metals in the soil.