TY - Generic T1 - The effects of quantity and duration of simulated pollutant nitrogen deposition on root-surface phosphatase activities in Calcareous and acid grasslands: a bioassay approach Y1 - 1999 A1 - Johnson, D. A1 - Leake, J.R. A1 - Lee, J.A. JF - New Phytol VL - 141 ER -