To investigate the characteristics of soil phosphorus forms in Phyllostachys praecox stands

samples of upper (0-20 cm) and lower (20-40 cm) soil layers were collected from fractions which were intensively managed for 3

9 and 15 years

respectively. The soil physo-chemical properties such as pH

soil organic carbon (SOC)

total phosphorus (TP)

Olsen P

and Mehlich-3 P were determined. Additionally

the concentrations of different phosphorus fractions were measured with modified Hedley’s sequential extraction procedures. The results showed that the pH of top soil significantly decreased in the 9- and 15-year intensive management plots where acidifications of subsurface soil were observed. The SOC mainly accumulated in the top soil layer

and the highest SOC content was observed in the 15-year intensive management stands

which increased by 183% compared to the 3-year intensive management plots. Moreover

the contents of TP

Olsen P

Mehlich-3 P

labile P (H2O-P+NaHCO3-Pi+NaHCO3-Po) and moderately labile P (NaOH-Pi+NaOH-Po) in both soil layers all increased with the prolonging of plantation time. Compared with the 3-year intensive management plots

the proportion of labile P and moderately labile P in the 15-year intensive management stands increased by 63% and 83% for topsoil layer

and 88% and 128% for the lower soil layer

respectively

however

the proportions of sparingly labile P (HCl-P+Res-P) decreased from 58% to 26% for topsoil layer and from 66% to 29% for lower soil layer

respectively

whereas the contents of sparingly labile P had no significant difference between these two treatments. Thus

applied phosphorus fertilizer was mainly built up in the labile P and moderately labile P fractions under the P. praecox stands. According to the Mehlich-3 P-H2O-P linear equation

we could speculate that phosphorus loss may have occurred in both soil layers. Therefore

fertilization should be properly managed in P. praecox stands to avoid excessive phosphorus loss.