基于图像分析的土壤速效磷的测定

An Image Analysis-based Determination of Available Phosphorus in Soil

对基于图像分析的土壤速效磷的测定方法进行了研究。在一定的浓度范围内，显色后的溶液磷浓度与图像的平均蓝色度有较好的线性关系。通过设置不同的磷标准溶液浓度范围，研究了图像分析法适用的范围。研究结果表明，相对于传统比色法，图像分析法在标准溶液浓度小于0．1mg·L^-1时，溶液磷浓度与网像的平均蓝色度不呈线性关系，但在0．1-4mg·L^-1的范围内，溶液磷浓度与图像的平均蓝色度有较好的线性关系。土壤待测液的体积与图像平均蓝色度的线性关系好于它与光密度之间的线性关系。当土壤有效磷的浓度在0．31～250mg·kg^-1Dw时，图像分析法可以确保分析精度。基于图像分析的土壤速效磷的测定方法是一种能现场测定，比试纸法精确度高，比传统比色法操作简单，且适应浓度高的土壤速效磷的测定方法。

The image analysis-based determination of available phosphorus in soil was investigated. In certain range of concentrations, there existed a good linear correlation between the average blueness of image and the concentration of phosphorus in solution after ehromogenesis. The various range of phosphorus concentrations in standard solution was set up to study the application of image analysis method. Compared with the conventional eolorimetric measurement, the image analysis method did not obtain linear relations between the phosphorus concentration and the average blueness of image when the phosphorus concentration in standard solutions was lower than 0.1 mg·L^-1. Good linear relations stand between the phosphorus concentration and the average blueness of image when the phosphorus concentration in standard solutions lies in the range of 0.1 to 4.0 mg·L^-1. The determination based on image analysis eould realize the analysis of available phosphorus in soil higher in concentration and greater in the change of concentration, to which the conventional colorimetric measurement was not applicable. The available phosphorus being determined, the linear relationship between volume and the average blueness of image was better than that between volume and optical density of soil solution. The determination based on image analysis could also obtain reliable precision when the concentration of available phosphorus in soil was between 0.31-250 mg·kg^-1DW. The measurement, which couht be implemented in situ, was more precise than the paper test, more convenient than the conventional eolorimetric one, and suitable for the determination of the available phosphorus with higher concentration in the soil.