Summary:
For nutrient potential assessment in forest ecosystem research, the
soil skeleton (fraction > 2 mm) is regarded as chemically inert in
short or medium time considerations. Only a long term effect is
attributed by means of weathering / alteration.
However, recent research has shown that the soil skeleton may have a
substantial exchange capacity and therefore needs to be considered in
any assessment of short and medium time available element supplies in
soil. So far known methods for direct measurement of available nutrient
potentials from weathering of the soil skeleton are time consuming and
costly and therefore not applicable as routine methods for soil
monitoring.
Thus, the aim of this project is the development and validation of
easily applicable methods for the assessment or estimation of nutrient
potentials of the soil skeleton.
In previous studies, two approaches have shown good prospects:
Elaboration of pedo-transfer functions
Easily measurable soil parameters are to be tested as predictors of the
soil skeleton exchange potential. For the crystalline bedrocks of the
Southern Black Forest region, adequate predictors have already been
identified and transfer functions have been established, explaining 30
to 50 % of variation in effective cation exchange capacity (CECe) and
nutrient supply in soil skeleton (HEISNER et. al. 2004).
Direct determination of soil skeleton Exchange capacity
A method for direct determination of CECe of the soil skeleton is to be
developed in analogy to routine methods for determination of CECe of
fine earth. Preliminary work has shown that in principle an already
existing method can be applied.
Furthermore, with only marginal additional work and expense, an
estimation of the methodological error caused by sieving and
homogenizing the fine earth before measurement of CECe can be
accomplished.
Results of all these surveys shall contribute to an area-based
assessment of nutrient supplies in soil monitoring, especially in the
second edition of the German Soil-state survey in forests (BZE II).
First results can be found here:
BLE_04HS024_Sachstand_03_2005.pdf
BLE_04HS024_Zwischenbericht_05_2005.pdf
duration: 15.11.2004 - 31.05.2006
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