Changes in soil chemistry accompanying acidification over more than 100 years under woodland and grass at Rothamsted Experimental Station, UK

Abstract

Summary We have examined the effect that acid deposition and other sources of acidity have had over the last 110–140 years on soil under woodland (Broadbalk and Geescroft Wildernesses) and grassland (Park Grass) comprising some of the Classical Experiments at Rothamsted Experimental Station. Changes in soil chemistry have been followed by analysing some of the unique archive of stored samples for pH, water‐soluble and exchangeable base cations, aluminium, iron and manganese, exchangeable acidity, cation exchange capacity (CEC) and soluble anions. Proton balances and historical data show the importance of acid deposition to acidification and concomitant changes in the chemistry of the soil. The pH of the surface soil of Geescroft Wilderness has fallen from 6.2 to 3.8 since 1883. The decrease in the pH of the unlimed, unfertilized plot on Park Grass was less over a similar period (from pH 5.2 to 4.2), illustrating the significant effect of the woodland canopy on the interception of acidifying pollutants. The effect of increasing acidity on the soil chemistry of Geescroft Wilderness is seen in its decreasing base saturation and CEC, with base cations moving down the soil profile. Clay minerals are being irreversibly weathered, and Mn and Al progressively mobilized, so that today Al occupies 70% of the exchange complex in the surface soil. Even with present reductions in sulphur deposition critical loads for sulphur, nitrogen and acidity are still exceeded. Such semi‐natural ecosystems are unsustainable under the current climate of pollution.

Impact of tree species on nutrient and light availability: evidence from a permanent plot study of old-field succession

“…It has been shown that changes in soil reaction during succession depend on initial pH. Thus, acidification during succession varies according to soil type and initial buffering capacity (Blake et al 1999;García et al 2007) and only a slow decline in soil reaction on soils with high buffering capacity (like our study site) is expected (Leuschner and Gerlach 2000). The decreasing amount of phosphorus in the soil indicates accumulation of phosphorus in the living plant biomass.…”

Contrasting pH buffering patterns in neutral-alkaline soils along a 3600 km transect in northern China

“…On the other hand, lowering the pH of carbonate-containing soils would, to some degree, improve their quality and thus increase the vegetation cover and biological productivity (Lieb et al, 2011;Yang et al, 2012). In the non-carbonate-containing soils, an increase in soil acidity may reduce availability of some nutrient cations, such as Ca and Mg, and enhance availability of some toxic cations, such as aluminum (Al) and manganese (Mn), which might limit plant growth and increase susceptibility to low temperature, drought and herbivory stress in these ecosystems (Blake et al, 1999;Lieb et al, 2011;Chen et al, 2013).…”

Determination of critical pH and Al concentration of acidic Ultisols for wheat and canola crops

“…However, in recent decades, various anthropogenic activities have accelerated soil acidification to a great extent. Acid deposition resulting from air pollution is a major cause for increased soil acidity (Reuss and Johnson, 1986;Blake et al, 1999). At present, acid deposition is still a serious factor that accelerates soil acidification in China (Vogt et al, 2006;Zhao et al, 2009).…”