钾电极在土壤中速效性钾的测定中的应用

Application of potassium ion-selective electrode in determination of exchangeable potassium in soils

用钾离子选择性电极可以测定土壤中的速效性钾。可用0.5mol/L BaCl_2溶液作提取液。当在室内测定时,提取时间以半小时为宜;当在野外现场测定时,提取时间为10分钟即可。提取交换性钾时,连续振荡与间歇振荡的效果接近。钾电极可直接用于土壤悬液中测定。为了避免NH_4^+或H^+的干扰,可用3mol/L LiOH溶液将土壤提取液的pH调至11左右。电位法与火焰光度法的测定结果基本一致。

potassium ion-selective electrodes can be used for the determination of exchangeable potassium in soils. 0. 5 mol/L BaCl2 solution was a suitable extracting solution of exchangeable potassium. Extraction duration of 30 minutes was enough when the determination was carried out in the laboratory, and that of 10 minutes was acceptable when the determination was carried out in the field. A potassium ion-selective electrode could be directly used in soil suspension. In order to eliminate the interference of NH+4 and H+, the pH value of the extracting solution should be adjusted to 11 with 3 mol/L LiOH solution. The results obtained by potentio-metric method was fairly agreed with that obtained by flame photometric method.