Phosphorus Turnover in Soil and Its Uptake by Established Lolium perenne Plants

Abstract

(1) A technique is described for measuring the time-course of uptake of 32p from soil by Lolium perenne plants. (2) Carrier-free 32p was applied to the soil and the 32p content of leaves was determined non-destructively every 1 or 2 days. When 32p uptake had almost ceased the plants were harvested and their total 32p content was determined. (3) Well-established plants took up 10-40% per day of the phosphorus in the soil labile pool. The transfer in the soil from labile to non-labile forms per day always exceeded this. (4) Since the amount of phosphorus in the labile pool cannot have been changing rapidly, phosphorus transfer from non-labile to labile and from labile to non-labile forms must have been going on simultaneously and rapidly. The half-time for phosphorus residence in the labile pool was about 1-2 days. (5) The method has potential for the further study of phosphorus turnover and uptake in pots and in the field.