The experiments started during the first year of the second phase of this project were continued, such as studies about the effect of trees on soil phosphorus and sulfur abailability, dissolved organic nutrients in rainfall, throughfall, stemflow and soil solution. Additionally, we focussed on the effects of cover crops on tree nutrition, soil nutrient and water dynamics. Soil nitrogen and phosphorus uptake was investigated using different N-15 and P-32 tracer experiments. The fate of fertilizer nitrogen was studied with N-15 labelled ammoniumsulfate in plant, soil, soil extracts and soil solution. In laboratory incubations, the effect of leaf quality on decomposition and incorporation of nutrients into soil organic matter was studied as affected by soil microbes and soil fauna.
Annual Report 1999. Compiled by Johannes Lehmann and Klaus Kaiser.