2 Ergebnisse.

Protozoa are active components of the soil microfauna. For example, they may stimulate bacterial metabolism and some fungal metabolites can lyse protozoa. They may be predators of bacteria and hence have a role in biological control. Their presence in groundwaters can be used as an indicator of pollution, while they are also being used to treat sewage in the activated-sludge and reed-bed processes. They are believed to be major secondary decom...

The success of shifting cultivation systems developed by subsistence farmers testifies to the resilience of the "natural" soil-plant ecosystems to recover from the offtake of nutrients in crops and loss of soil struc­ ture. By contrast, the development of intensive cropping systems requires large inputs especially of nitrogen, together with phosphorus, sulphur and other essential elements in order to maintain the nutrient levels needed for abu...