Nitrogen recovery in soil and needle biomass after fertilization of a Scots pine stand, and growth responses obtained
Nömmik, Hans; Möller, Göran
The distribution of fertilizer nitrogen in soil and needle biomass of an 120-year-old stand of Scots pine was studied over a period of six years. The nitrogen was applied as ammonium nitrate or urea and at rates of 150,300 and 600 kg N per hectare. The soil investigations showed that, at the lowest nitrogen application rate, 21 % of the ammonium nitrate and 49% of the urea nitrogen were immobilized in the soil in nonexchangeable form. For the corresponding treatments the losses by leaching were estimated to 3040% and 0-lo%, respectively. The accumulation of fertilizer nitrogen in the needle biomass culminated during the third growing season. Relative to control, the total nitrogen accumulation for the lowest ammonium nitrate and urea application rates then amounted to 174 and 134% respectively. As regards volume growth, the ammonium nitrate was greatly superior to urea at the two lowest nitrogen application rates. The dose of 600 kg N per hectare proved to be over-optimal as far as the ammonium nitrate source of nitrogen was concerned.
Scots pine; nitrogen distribution; immobilization; leaching; ammonia volatilization; pH changes; ammonium nitrate; urea
Studia Forestalia Suecica
Utgivare: College of Forestry, Swedish University of Agricultural Sciences
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