Intensive fertilization with nitrogen as a stressing factor in a spruce ecosystem. 1, Soil effects

Abstract

Soil studies were carried out before and after clear felling of an intensively fertilized young spruce plantation on old arable land. Particular attention was devoted to nitrogen mineralisation, nitrification, and leaching. Notable amounts of nitrate in the soil occurred before felling only on plots receiving high doses of amrnonium nitrate, after clear felling also on some plots with no or low nitrogen supply. Marked quantities of nitrate nitrogen were observed in the deeper soil layers during the fertilizer experiment in plots with high fertilizer additions. The soil reaction indicated an acidification as a result of fertilizer treatment. In a pot experiment with soil from the field experiment the nitrate leaching by percolation was studied. Most of the leaching of nitrate nitrogen occurred in the first phase of the experiment. After the vegetation was established, the nitrate concentration in the percolating water rapidly decreased