宁夏灌淤土对磷吸附的初步研究

本文报道了宁夏灌淤土12个代表性土样对磷的等温吸附与解吸特性。实测吸附曲线与Preundlich、Langmuir和Temkin三种等温吸附方程都很吻合。全部供试样品的相关系数变化在0.931-0.999之间,均达极显著水平(p<0.01)。其中Langmuir等温式与本实验资料最为吻合。供试土壤对磷的最大吸附量(X_m)变化在172-460μgP/g之间,平均为347±28μgP/g。影响其大小的因子主要是物理性粘粒和CaCO₃,含量,均达极显著正相关。灌淤土不同土层的吸磷量大小依次为:剖面24>23>21>22,而解吸磷能力大小依次为:剖面23>22>21>24。磷的解吸量与吸附量之间呈极显著正相关。根据本试验数据,土壤对磷的等温吸附曲线可以用来预测土壤需磷量。

A PRELIMINARY STUDY ON PHOSPHATE ADSORPTION BY WARPED IRRIGATED SOIL IN NINGXIA

The present paper deals with the characreristics of isothermal phosphate adsorption and desorption of warped irrigated soil collected from Yinchuan Plain in Ningxia. The data of isochermal phosphate adsorption of the twelve soil samples tested in a wide range of phosphorus concentration (up to 3097 ug P/g) were all found to be in close agreement with the Freundlich, Langmuir and Temkin equations. Their correlation coefficients (r) ranged from 0.931 to 0.999, with a very significant level (P<0.01). Among these equations the Langmuir adsorption isotherm seems to be the best fitting model.The P adsorption maxima of the soil samples tested as estimated by the Langmuir equation varied from 172 to 460 ug P/g. Their average was approximately 347±28 ug P/g. The relationships between the P adsorption maxima and some soil properties have been examined by simple linear regression analyses. Results have showed that P adsorption maxima were in fairly significant direct correlations (P<0.01) to the contents of physical clay and CaCO₃ in warped irrigated soil. According to the experimental data in the paper, the isothermal phosphate adsorption curves of soils could be used for predicting the requirement of phosphorus fertilizer for soils.