福州市郊菜地土壤磷素特征及流失潜能分析

Analysis on Characteristics and Lost Potential of Soil Phosphorus in Vegetable Field Located at Suburb of Fuzhou City

对福州市郊11片蔬菜基地土样的磷素含量、等温吸附特征及流失潜能进行分析。结果表明：与林坡地自然土壤相比,菜地土壤全磷（2.043 g/kg）、速效磷（Oslen-P,182.893 mg/kg）和CaCl2-P（1.018 mg/kg）平均含量都呈现出明显的累积特征;菜地土壤可用Langmuir等温方程很好拟合（R^2=0.991＊＊-0.998＊＊）,其等温吸附特征值,如易解吸磷（RDP）、磷吸持饱和度（DPS）和磷零吸持平衡浓度（EPC0）均出现大幅度提高,而最大缓冲能力（MBC）和吸附常数K则明显降低;据Langmuir方程求得菜地土壤指导施磷量范围为11.62-67.37（P）kg/hm^2,平均为27.18（P）kg/hm^2;菜地土壤的速效磷和全磷含量均显著高于由回归方程求得的土壤发生磷素淋失的速效磷临界值（56.96 mg/kg）和全磷的临界值（1.146 g/kg）;菜地土壤的DPS平均为23.12%,已经接近容易流失的阈值（25%）,其中4片菜地土样的DPS已经超过容易流失的阈值。因此,福州市郊菜地土壤磷素具有很高的流失潜能,应作为农业面源磷污染控制的关键源区。

Phosphorus content, isotherm sorption characteristics and lost potential of soils sampled from 11 pieces of vegetable base located at suburb of Fuzhou city were analyzed. Results showed that ： Compared with natural soil sampled from forest sloping field, the average contents of total phosphorus （2.043 g/kg）, quick result phosphorus （Oslen--P, 182. 893 mg/kg） and CaCl2--P（1. 018 mg/kg） of vegetable field soils were obviously accumulated; Langmuir isotherm equation was simulated well on vegetable field soils （R^2 =0. 991^＊＊ -0. 998^＊＊ ）, and their isotherm sorption characteristics, such as Readily Desorbed Phosphorus （RDP）,Degree of Phosphorus Saturation （DPS） and EPC0 were increased largely, but Maximum Buffering Capacity （MBC） and sorption constant （K） were decreased obviously; The range of instructive phosphorus rate used in vegetable field soils calculated by Langmuir equation was 11.62- 67. 37 （P）kg/hm^2, the average was 27.18 （P）kg/hm^2;The contents of quick result phosphorus and total phosphorus of vegetable field soils were largely higher than their critical value of leaching （56.96 mg/kg and 1. 146 g/kg） calculated by regression e quation, respectively; The average DPS of vegetable field soils was 23.12%, which was close to the threshold value （25%） of soil phosphorus readily lost, but the DPS of 4 pieces of vegetable field soils was beyond the threshold value. Consequently, the phosphorus lost potential of vegetable field soils from the suburb of Fuzhou city is rather high, so vegetable field should be considered as the critical source area of phosphorus pollution.