Potential nitrogen transfer and regulation through brown acid soils under beech and spruce stands

Abstract

Lysimeter experiments were carried out in the Belgian Ardennes, under spruce and beech stands, on brown acid soil with moder humus form. In the first experiment, tagged nitrogen salts were added to the lysimeters under spruce. Balance sheets show in all cases the presence of nitrates in the leachates, and some evidence of denitrification losses in the case of nitrate, and of ammonium+basic slag additions. In the second experiment, leachates of lysimeters installed under spruce and beech, were analyzed for nitrogen, protons and organic carbon. The authors show the differences between potential transfer, when absorbing roots are absent, and the actual transfer when roots are present. The authors refer to the perturbation theory of Ulrich and stress the difficulty of estimating ΔN, the mean soil nitrogen increment in kg/ha/year.