Budgets and Cycling of Phosphorus of Leymunes chinenses in Vegetation-Soil Subecosystem in Arid Temperate Grassland

In natural grassland in north-east China, the allocation, dynamics, cycling and the flow rates of P were studied, and the relations between various P pools and !ability of P were analysed, The results were that (l) OPe-P and OCa-P are dominant forms in soil; the effect of inorganic P on labile phosphorus (LP) is negligible. LP primarily comes from organic P, especially from labile organic P and micro­organism P. (2) The net budget of P is 2,837 kg/ha/year in the community with an output 1.5538 kg/ha/year from lhe ecosystem. (3) The mineralisation rate of organic P is about 0.0026 gig/year in soil. (4) The absorption of P by the roots is about 7.3382 kg/ha/year, 25.4% to aboveground and 86. 1 % to belowground, (5) The dead material P return is about 2.9533 kg/ha/year. (6) The P turnover times in live plant, stand dead, organic P, dead root and live root pools are 1.1614, 6.6225, 384.6145, 2.1142 and 1.4738 years, respectively.