Changes in recovery of native and applied phosphorus with time as affected by soil properties in some calcareous soils

摘要

In an attempt to investigate variations in availability of native and applied phosphorus (P) with time, twenty five calcareous soil samples were treated with 0, 50 and 500 mg P kg(-1) soil and incubated at 80-90% of field capacity moisture content in an open door glasshouse for a period of one year. Soil samples were taken out at certain intervals for P extraction with Olsen extractant under moist condition. Results indicated that following wetting the mean value of native Olsen-P decreased initially and then increased gradually with time of incubation. Generally, the short term (24 h) recoveries were not correlated with long term ones. The recovery of added P with time was described properly by the following new proposed model: R = 100/(1 + kt(b)), where R is percent recovery at time t, and k and b are empirical parameters. The values of k constant at 50 and 500 mg P kg(-1) were in the ranges of 0.40 to 1.22 (0.84 +/- 0.25, on average) and 0.04 to 0.52 (0.23 +/- 0.14, on average), respectively. The corresponding respective values of b constant also ranged from 0.05 to 0.32 (0.15 +/- 0.06, on average) and 0.12 to 0.92 (0.46 +/- 0.23, on average).