Blaser P, Graf Pannatier E, Walthert L (2008) The base saturation in acidified Swiss forest soils on calcareous and non-calcareous parent material - A pH-base saturation anomaly. Journal of Plant Nutrition and Soil Science , 171: 155-16. [10.1002/jpln.200625213]


pH, base saturation, soil water regime, decalcification, acidification, hydromorphy, LWF plot Lausanne, LWF plot Vordemwald, LWF plot Novaggio, ICP-Forests


Long-term soil acidification leads to lower pH values and to a concomitant decrease in base saturation (BS). The relationship between pH and BS in acidified forest soils can be disturbed by processes such as nutrient cycling by vegetation, temporary saturation by ground water that comes into contact with calcareous material or by upward diffusion of base cations from deeper horizons. This paper examines the relationship between pH and BS in Swiss forest soils developed from calcareous and non-calcareous parent material and identifies some of the factors that can affect the BS in the decalcified parts of soils derived from calcareous parent material. The decalcified zone in the latter soils has a higher BS on average compared to soils from non-calcareous parent material, but their pH values are identical. In the pH-range 4.0 – 4.5, the difference in BS may vary by a factor of three. The mean BS in the decalcified zone tends to decrease with increasing depth of the calcareous layer. The water regime also affects the BS in soils on calcareous parent material. In soils temporarily saturated by groundwater (Gleys), the BS in the decalcified zone is always high (85% – 100%) because of the continuous contact between the soil water and the calcareous parent material. In addition, the inhibited drainage impedes the depletion of base cations in these soils. In contrast, soils that are temporarily saturated by rainwater are depleted in base cations due to the alternating wetting and drying regime and the associated leaching of dissolved ions. In such soils the depletion of base cations is strongly related to the extent of hydromorphy. Stagnogleyic soils, with the longest period of water saturation, have the highest depletion levels. We conclude that in such soils the diffusion of base cations from deeper zones is strongly compensated by leaching from the very acidic soil horizons. The pH-base saturation anomaly has consequences for some of the methods used to calculate the critical loads of acidity for forest soils in Switzerland, with many soils being less sensitive than previously reported.

LWF Classification

Network: LWF, Sites: Alptal, Beatenberg, Bettlachstock, Celerina, Chironico, Isone, Jussy, Lausanne, Lens, Neunkirch, Novaggio, Schänis, Visp, Vordemwald, Category: ISI,