Expression of Soil Nutrient Status and Regional Variation in Soil Fertility of Forested Sites in Southern Finland

1991

40 S.

3 Abb., 28 Tab., 34 Anh., zahlr. Lit. Ang.

Bandaufführung

2628

37292

Soil sampling of 1248 forested sample plots in southern Finland was carried out during 1980-85.pH (in water), total nitrogen, and ammonium acetate (pH 4.65) extractable P, K, Ca and Mg concentrations were determined from humus layer and surface mineral soil (0-30 cm) samples. Total concentrations pf P, K, Ca and Mg were also determined from the humus samples. Only texture was determined from subsoil (65-75 cm) samples. The nutrient concentrations of the humus layer, especially nitrogen, were best correlated with site index when expressed on an organic matter basis. In mineral soil, nitrogen concentration on an organic matter basis and calcium and magnesium amounts per hectare had the best correlations with site index. Soil pH and organic matter and clay contents poorly explained nutrient concentrations. In the humus layer, acid ammonium acetate extracted 90% of total potassium, 69% of total calcium, 57% of total magnesium and 3% of total phosphorus. Of the site characteristics determined, forest site type had the best correlation with nutrient parameters. Nitrogenand magnesium were the nutrients that best classified site types. The nutrient status of the humus layer was effected by the composition of the forest stand - nutrient status was best under broadleaved stands and poorest under old, coniferous stands. There were clear differences in site fertility between the study areas. These differences were evident both in the distribution of site types and in nutrient concentrations.