Critical loads for acidity and nitrogen for Dutch forests on a 1 km x 1 km grid

Critical loads were derived using a one-layer steady-state model that includes mineral weathering, nutrient uptake, nitrogen transformations, and an acceptable leaching rate of acidity or nitrogen. Values were calculated for combinations of 12 tree species and 23 soil types. Acceptable leaching rates of acidity were calculated as a function of tree species. Critical acid loads for non-calcareous forest soils proved to be higher than those derived in former regional studies. They are most influenced by soil type and generally increase in the direction sand - loess - clay - peat. Critical loads for clay and peat are preliminary; they are probably too high.