Experimental N fertilization of Scots pine: effects on soil-solution chemistry 8 years after final felling

Previous N fertilizations in boreal forests may increase the leaching of elements such as NO3- and Al after final felling. In order to study such effects, soil-solution chemistry was investigated during the eighth growing season after final felling a Scots pine stand in central Sweden. This stand had been subjected to experimental N fertilization, with the latest application performed 6 years before final felling. Soil solution at a depth of 50 cm was collected with Teflon and ceramic suction cups in duplicate plots to which ammonium nitrate had been applied three times, giving total N doses of 0, 360 and 1800 kg ha^-1. Compared with the control, the 360 kg N ha^-1 treatment showed no significant (P>0.05) effects on soil-solution chemistry. The 1800 kg N ha^-1 treatment tended to have higher concentrations of H+, total Al, Mn, NO3 -N, total N and F-, and lower acid-neutralizing capacity than both the control and the 360 kg N ha^-1 treatment. Forest fertilization with 1800 kg N ha^-1 negatively affected soil-solution chemistry after final felling as opposed to the low fertilizer dose common in Swedish silviculture. While the study provides only a snapshot in time, a final conclusion could not be drawn for the low fertilizer dose.