集约经营雷竹林土壤磷素状况及流失潜能

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

为了解集约经营雷竹Phyllostachys praecox林土壤磷素状况及流失风险,从浙江省临安市太湖源镇10块典型的雷竹林地采集土壤样品。通过等温吸附实验及利用Langmuir等温方程,对雷竹林土壤磷的流失阈值及流失潜能进行了探讨。结果表明：10块雷竹林地的土壤有效磷质量分数平均为169.25 mg·kg-1。用Langmuir等温方程来拟合,相关性达到极显著水平（R2=0.987~0.999）。所有调查样地土壤的磷零点吸附平衡质量浓度（CEPC0）值远远超过了0.02 mg·L-1;磷吸附饱和度（DPS）平均值为46.18%,最高的达82.94%,有7块样地的DPS值明显高出临界值（25.00%）。土壤有效磷与CaCl2-P呈极显著线性相关,雷竹林土壤发生磷素流失的有效磷＂阈值＂为52.52 mg·kg-1,10块样地中有9块样地的有效磷质量分数超过了阈值,最高的达到该＂阈值＂的5.5倍。通过Langmuir方程,求得雷竹林土壤的标准需磷量为8.14~64.66 kg.hm-2,平均为27.41 kg·hm-2。

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 Lin＇an, 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 mg.kg-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 （CErC0） 〉 0.02 mg.L-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 CaCI2-P and Bray-P. The threshold Bray-P for phosphorus leaching from soils was 52.52 mg.kg-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 kg-hm-2 with an average of 27.41 kg.hm-2. [Ch, 2 fig. 2 tab. 29 ref.]