Small-Scale Soil Functional Mapping of Crop Yield Potentials in Germany

Abstract

The Muencheberg Soil Quality Rating (M-SQR) is a new approach for assessing soil suitability for arable and grassland farming, and estimating crop yield potential on a global scale. We utilized this approach to construct a small-scale map of crop yield potentials covering arable lands in Germany. M-SQR rules and algorithms were adapted to the terminology and classification of soil parameters as defined by German soil mapping guidelines and were applied to soil profile-related data sets of the land-use stratified soil map of Germany at a scale of 1:1,000,000. According to the resulting thematic map, soils in Germany show a high yield potential for grain; the nationwide mean score accounts for 64 out of 100 possible points. Moderate drought risk is the main crop yield limiting factor in Germany, shallow soil depth, and other crop yield limiting factors may also be locally important. The approach has been validated and tested in comparison with the traditional German Bodenschatzung (German soil assessment). In comparison to the Bodenschatzung classification scheme, which is conventionally applied to assess the yield potential of agriculturally used soils, the M-SQR method incorporates additional climatic variables and considers site-specific drought risks. The two methods, the M-SQR approach and the German Bodenschatzung system, were compared and evaluated on the basis of grain yield data from 79 sites from different Federal States of Germany. In general, the M-SQR method provides reliable estimates of the yield potential for cereals. As the Basic Rating of M-SQR correlates significantly with scores (Ackerzahl) of the Bodenschatzung, both systems are potentially convertible. On average, M-SQR point scores even correlate slightly better to measured yields than Bodenschatzung scores. We conclude that this may enable the creation of reliable medium- and large-scale crop yield potential maps within Germany using the M-SQR methodology, available digital soil maps, and climate databases. The M-SQR methodology also enables the consistent incorporation of the newly created small-scale German crop yield potential map into a potential small-scale global soil quality map.