Nutrient acquisition from different soil depths by pedunculate oak

Abstract:
Eight oak trees (Quercus robur L.) received P-32 at a soil depth of 50 cm and P-33 at a soil depth of 15 cm at the end of June 2002 through plastic tubes inserted into the mineral soil. The phosphorus uptake from different soil depths was estimated by analysing the concentration of P-32 and P-33 in the foliage of oak growing in a mixed stand in southern Sweden. P-32 and P-33 were recovered in the leaves/needles after 21 and 39 days. The recovery of labelled P in oak was higher from 15 cm soil depth than from 50 cm, however, more than 4% of the total amount of labelled P was taken up from 50 cm. This indicates that oak can utilize deep soil layers for nutrient uptake. A study on the uptake of Cs (as an analogue to K) and N-15 into the leaves was performed on the same trees and detectable amounts of N-15 and Cs were recovered in leaves and buds. This indicates that N-15 and Cs can be used to study nutrient uptake of mature trees from the mineral soil.