The effects of H2SO4 and (NH4)2SO4 treatments on the chemistry of soil drainage water and pine seedlings in forest soil microcosms

Abstract

An experiment comparing effects of sulphuric acid and reduced N deposition on soil water quality and on chemical and physical growth indicators for forest ecosystems is described. Six H 2 SO 4 and (NH 4 ) 2 SO 4 treatment loads, from 0 44 and 0 25 kmol c ha -1 yr -1 , respectively, were applied to outdoor microcosms of Pinus sylvestris seedlings in 3 acid to intermediate upland soils (calc-silicate, quartzite and granite) for 2 years. Different soil types responded similarly to H 2 SO 4 loads, resulting in decreased leachate pH, but differently to reduced N inputs. In microcosms of calc-silicate soil, nitrification of NH 4 resulted in lower pH and higher cation leaching than in acid treatments. By contrast, in quartzite and granite soils, (NH 4 ) 2 SO 4 promoted direct cation leaching, although leachate pH increased. The results highlighted the importance of soil composition on the nature of the cations leached, the SO 4 adsorption capacities and microbial N transformations. Greater seedling growth on calc-silicate soils under both treatment types was related to sustained nutrient availability. Reductions in foliar P and Mg with higher N treatments were observed for seedlings in the calc-silicate soil. There were few treatment effects on quartzite and granite microcosm tree seedlings since P limitation precluded seedling growth responses to treatments. Hence, any benefits of N deposition to seedlings on quartzite and granite soils appeared limited by availability of co-nutrients, exacerbated by rapid depletion of soil exchangeable base cations.

Nutrient resorption tightens plant nitrogen and phosphorus coupling and decreases with sulfur deposition as mediated by interannual precipitation in a meadow

“…Furthermore, soil acidi cation could increase soil P availability via exchanging PO 4 3− from soil minerals and promoting activity of acid phosphatase (Jaggi et al 2005). However, this direct S supply would promote soil S availability in a greater degree than that of N and P. As a result, chronic but continuous S deposition translates into asynchronous increases in soil N, P, and S availability to differentially promote plant nutrient uptake (Brown et al 2000;Jaggi et al 2005;Stutter et al 2004;Wang et al 2002).…”

Sustainability of UK forestry: contemporary issues for the protection of freshwaters, a conclusion

“…Studies by Sheppard et al (2004) based on dosing experiments for a young Sitka Spruce stand on acid peat soil showed that these trees are able to buffer the low nutrient levels and produce new growthonly if there is sufficient N. Inputs of almost 100 kg-N ha 1 yr 1 in addition to ambient N resulted in elevated foliar N and N 2 O losses and increased soil water N, but did not reduce stem area growth. In a dosing experiment by Stutter et al (2004), the effects of H 2 SO 4 , (NH 4 ) 2 SO 4 and reduced N deposition on soil water quality was linked to chemical and physical growth indicators for pine seedlings. The results depend strongly upon the type of soil.…”