ABSTRACT
Mineral elements were identified as essential factors for plant growth by German chemist Justus von Liebig as long ago as 1840, whereas human awareness that the fertility of land is variable in space is most likely as old as farming itself (since ca. 10000 BC) with references to this problem mentioned in the Bible (e.g. Luke 8:5-6). Soils are neither static nor homogenous in space and time, and this directly influences the concentration of plant-available nutrients. One of the most impressive examples of the spatial variation of plant-available nutrients is the phenology of the sulfur (S) supply of oilseed rape (Figure 4.1). Under humid conditions the variability of physical and hydrological soil properties within the soil profile results in a high spatio-temporal fluctuation of soil sulfate contents that becomes visible in different degrees of S deficiency symptoms (Schnug and Haneklaus, 1998). Spectral signatures from remotely sensed data were successfully used to follow up S deficiency on a large scale (Lilienthal and Schnug, 2005).
