Großmaßstäbige Regionalisierung labiler Bodenkennwerte in standörtlich hochdiversen Kulturlandschaften

Abstract

Regionalization of Soil Properties of Topsoils on a Large Scale in Highly Diverse Landscapes

For the spatial valuation of many soil and landscape functions large scale maps (1:5,000 to 1:10,000) of spatio-temporally highly variable (labile) soil properties, like the pH value, the organic carbon or the EDTA-extractable cadmium content, are needed. In rural mountainous areas, which are of less political or economical interest, such maps are usually missing.

Especially in these regions the lateral variability of labile soil properties is determined by the spatially very heterogenous soil-forming factors. Furthermore, the labile soil properties mostly change within short distances near land use boundaries. Under these circumstances, geostatistical techniques for generating large scale maps of the labile soil properties are not recommened. For a valid geostatistical interpolation numerous soil samples and chemical analysis would be necessary. However, in most projects manpower, financial and temporal resources are limited.

In these PhD thesis a concept is presented that allows a valid regionalization of labile soil properties in highly diverse landscapes with a small number of soil samples. The concept includes methods to determine the sample size, the sampling positions, the classification and the extrapolation of the labile soil properties. Furthermore, it comprises the validation methods for the regionalization model and results. The verification of the concept is carried out for the soil properties pH value, organic C, and EDTA-extractable cadmium content in topsoils of agricultural land in three testing areas with a surface area of 5 to 10 square kilometres. Furthermore, as a practical planning example, the exhaustion of national approximate figures of cadmium in the topsoils is regionalized and evaluated.

To regionalize the labile soil properties in the testing areas only 0.2 to 0.3 soil samples per 100 square metres are needed. The plausibility of the model is confirmed with an analysis of variance of the regionalization results. The validation of the regionalization results itself is proved with an independent random sample. Therefore, with the regionalisation model the pH, carbon and cadmium status of the top soils can be described with an average certainty of 75 per cent  if the soil properties are subdivided into three to four classes. The results of the practical planning example show that the exhaustion of national approximate figures of cadmium in the testing areas can be described spatially in a very  precise way including the regionalized soil properties and an available pedotransfer function.