Nitrogen and phosphorus leaching and uptake by container birch seedlings (Betula pendula Roth) grown in three different fertilizations

摘要

Leaching of nitrogen (N) and phosphorus (P) through container peat medium and N and P uptake by seedlings were determined in commercial production of birch grown with three different types of fertilization. Half of the amount of nutrients was premixed into the peat medium and the other half was applied as liquid (=fertigated) in the treatment (PF) commonly used in Finland. In two other treatments all nutrients, either totally (P-VN) or partly (P-N) in slow-release form, were premixed into the peat. Independently of the treatment, the largest proportion (60 to 80%) of total N leached during May and June. During two growing seasons, the amounts of N leached from PF treatments (9 to 36 kg ha(-1)) were as large as the amounts of N leached from P-VN and P-N treatments (24 to 46 kg ha(-1)). Due to fertigations between container trays, however, the total N load per hectare was greatest in the PF treatments. In the soil water 0.5 meter beneath the container area, the N concentration varied from 10 to 60 mg l(-1). The morphological and chemical properties of the seedlings did not differ greatly between treatments.