EFFECTS OF LIMING AND BORON FERTILIZATION ON BORON UPTAKE OF PICEA-ABIES

The effects of liming on concentrations of boron and other elements in Norway spruce [Picea abies (L) Karst.] needles and in the mor humus l ayer were studied in long-term field experiments with and without B fe rtilizer on podzolic soils in Finland. Liming (2000 + 4000 kg ha(-1) l ast applied 12 years before sampling) decreased needle B concentration s in the four youngest needle age classes from 6-10 mg kg(-1) to 5 mg kg(-1). In boron fertilized plots the corresponding concentrations wer e 23-35 mg kg(-1) in control plots and 21-29 mg kg(-1) in limed plots. Both liming and B fertilizer decreased the Mn concentrations of needl es. In the humus layer, total B concentration was increased by both li me and B fertilizer, and Ca and Mg concentrations and pH were still co nsiderably higher in the limed plots than controls. Liming decreased t he organic matter concentration in humus layer, whilst B fertilizer in creased it. The results about B uptake were confirmed in a pot experim ent, in which additionally the roles of increased soil pH and increase d soil Ca concentration were separated by means of comparing the effec ts of CaCO3 and CaSO4. Two-year-old bare-rooted Norway spruce seedling s were grown in mor humus during the extension growth of the new shoot . The two doses of lime increased the pH of soil from 4.1 to 5.6 to 6. 1, and correspondingly decreased the B concentrations in new needles f rom 22 to 12 to 9 mg kg(-1). However, CaSO4 did not affect the pH of t he soil or needle B concentrations. Hence the liming effect on boron a vailability in these soils appeared to be caused by the increased pH r ather than increased calcium concentration.