Nitrogen leaching and acidification during 19 years of NH₄NO₃ additions to a coniferous-forested catchment at Gårdsjön, Sweden (NITREX)

Moldan, Filip; Wright, Richard F.

Nitrogen leaching and acidification during 19 years of NH₄NO₃ additions to a coniferous-forested catchment at Gårdsjön, Sweden (NITREX)

2011

Moldan, Filip | Wright, Richard F.

The role of nitrogen (N) in acidification of soil and water has become relatively more important as the deposition of sulphur has decreased. Starting in 1991, we have conducted a whole-catchment experiment with N addition at Gårdsjön, Sweden, to investigate the risk of N saturation. We have added 41kgNha⁻¹yr⁻¹ as NH₄NO₃ to the ambient 9kgNha⁻¹yr⁻¹ in fortnightly doses by means of sprinkling system. The fraction of input N lost to runoff has increased from 0% to 10%. Increased concentrations of NO₃ in runoff partially offset the decreasing concentrations of SO₄ and slowed ecosystem recovery from acid deposition. From 1990–2002, about 5% of the total N input went to runoff, 44% to biomass, and the remaining 51% to soil. The soil N pool increased by 5%. N deposition enhanced carbon (C) sequestration at a mean C/N ratio of 42–59gg⁻¹.

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