Soil phosphorus and potential loss in Phyllostachys praecox stands with intensive management

Key words: 
• soil science /
• Phyllostachys praecox /
• soil phosphorus /
• threshold value /
• loss potential

Abstract: To reveal the soil phosphorus（P）status and its leaching risk for Phyllostachys praecox stands under intensive management with winter mulching and excessive fertilization，10 compositing surface（0 -30 cm） soil samples were collected in typical sites located across 5 villages in Linan，Zhejiang. The soil P loss threshold value and its potential for Ph. praecox stands were then determined by isothermal adsorption-desorption and the Langmuir isotherm equation. Results showed that the average available phosphorus for the ten soils sampled was 169.25 mgkg－1. Some good fitting Langmuir equations with R2 ranged between 0.987- 0.999** were yielded. For six sites，Equilibrium Phosphorus Concentration at Zero Sorption （CEPC0） ＞ 0.02 mgL－1；the average Degree of Phosphorus Saturation（DPS）of ten sites was 46.18% with 82.94% being the highest and seven sites being higher than the critical value 25% greatly. There was also a significant linear correlation（R2 = 0.835**） between the CaCl2-P and Bray-P. The threshold Bray-P for phosphorus leaching from soils was 52.52 mgkg－1，and with nine out of ten sites were higher than the threshold，and the highest was 5.45 times greater than this threshold. By application of Langmuir equation calculating the phosphate requirement for Ph. praecox stands was 8.14 - 64.66 kghm－2 with an average of 27.41 kghm－2.［Ch，2 fig. 2 tab. 29 ref.］