采用四苯硼钠为滴定剂 ,双电解池正反馈示波计时电位法确定终点测定土壤中钾含量 ,滴定在 p H大于 7的 Na OH- Na Ac碱性底液中进行 ,将溶液加热煮沸后 ,铵离子没有干扰。本方法测定的回收率在 99.5%～ 10 0 .5% ,准确度与火焰光度法接近 ,装置简单 ,操作简便 ,测量条件易于控制 ,适用土壤中全钾和有效钾的测定 Sodium tetraphenylborate was used as titrant and positive feedback oscillometric chronopotentiometry was used to determine the potassium content in the soil. The titration was carried out in Na OH-Na Ac alkaline solution with p H greater than 7. The solution was heated to boil After the ammonium ion did not interfere. The recovery of the method was 99.5% ~ 105.5%, accuracy and flame photometry close to the device is simple, easy to operate, easy to control the measurement conditions for the determination of soil total potassium and available potassium