Extraction and mapping of soil factors using factor analysis and geostatistical analysis on intensively manured heterogenous soils

To investigate both natural variability and anthropogenic inputs, a small lake catchment that collects water from slurry-irrigated (~300 m 3 ·ha -1 annual application) natural meadows was explored. Analysis of the distribution of heavy metals suggests that concentrations of Ni, Zn, Pb, and Cu are closely associated with the geochemical signatures of soil parent material and, to a lesser extent, with soil organic matter. The data set of selected soil parameters was subjected to factor analysis (FA), which reduced the dataset into two major components (Factors 1 and 2) representing the different elemental sources. Geostatistical analysis showed interrelationships between heavy metal accumulations and soil genetic properties. Contour mapping of these variables identified the areas where anthropogenic processes are especially evident. Such visual information allowed spatial identification of the optimum number of ‘tipping points’ for soil monitoring.