Abstract:

To improve the detection accuracy and efficiency of the cation exchange capacity in soil, and in view of the shortcomings of the national standard method, the authors optimized the experimental steps such as blank test, extraction and centrifugation under the same principle. The accuracy, precision and stability of the new method were analyzed through comparative experiments, parallel experiments and condition experiments. The results showed that the blank test was redefined by experiments, and the extraction time in the national standard method was optimized from 60 min to 30 min, as well as the centrifugation time was optimized from 10 min to 20 min, which greatly shortening the test time of a sample. Under these conditions, four different types of the certified reference materials of national soil were tested, and it was found that the measured values of cation exchange capacity were in agreement with the standard values of the certified reference materials of soil. This method possesses the advantages of high efficiency, excellent accuracy, precision, and simple operation, and is suitable for the determination of cation exchange capacity in large quantities of soil samples.

Key words: soil, cation exchange capacity, hexamminecobalt trichloride, extraction, centrifugation, spectrophotometry method, optimization and improvement