In organic production only organic fertilizers and soil conditioners can be used to supply
the soil with nitrogen. The mineralization of these products is slow and so there can be
problems with the supply of nitrogen, when the demand of the plants is high. The supply of
nitrogen from organic products depends on the speed of their mineralization which is
primarily influenced by the composition and formulation of their raw material.
In apple production in the Alps-region especially during spring problems with nitrogen
supply are common. In that period, the weather conditions are sometimes bad, the
temperature in the soil is low and mineralization starts slowly - apple trees demand more
nitrogen than the soil can deliver.
To compensate the demand of the apple tree organic growers can not use mineral
fertilizers but only organic fertilizers and soil conditioners whose mineralization rate is often
unknown. There is a strong need in organic fruit production to receive more information
about the behaviour of fertilizers in the soil especially concerning their N-release under
different conditions.
To acquire that information, incubation experiments under controlled conditions
(temperature, type of soil, humidity of the soil) were carried out in the laboratory to
determine the mineralization-rate of different organic fertilizers and soil conditioners which
are available in our region
