石灰性土壤缓效钾含量检测浸提方法的改进

The method improvement of extracting slow-release potassium from alkali soils

用硝酸提取方法测定石灰性土壤缓效钾含量过程中，在浸提溶液中加入一滴植物油作为消泡剂，可防止浸提液沸腾时溢出管口；用硬质大试管取代三角瓶，并用油浴取代电热板，每次浸提样品数量增加到60个左右，工作效率提高3—4倍。结果表明，浸提方法改进后，同一批样品浸提液开始沸腾时间前后相差5s左右，浸提液温度基本稳定在103．8℃，平行样检测结果的变异系数在1．2％～2．4％之间，重复样检测结果的变异系数在1．2％～3．3％之间。用改进方法测定不同含量的石灰性土壤缓效钾时，与常规方法有85％的符合率。改进方法测定值与参比土样定值平均值的相对误差在0．4％～3．8％之间。

An optimum method of extracting slow - release potassium using hot nitric acid from alkali soils was obtained. A drop of plant oil was added as a defoamer in case that soil samples and extracted solution overflow from the nozzles. A combination of large hard texture test tubes and oil bath which replaced that of conical flasks and electrothermal board could increase the amount of the tested samples up to 60 at one time and improve the work efficiency by 3 or 4 times. Taking into account the improved method, the time starting boil of different tubes varied only 5 s and the solution temperature was stabilized by 103.8℃. The parallel and repeating variance coefficient ranged from 1.2% to 2. 4% and from 1.2% to 3. 3%, respectively. The accordance rate of improved method was 85% to the traditional method during detecting the alkali soils with different slow - release potassium contents. The relative errors of improved method ranged from 0. 4% to 3. 8%, of which the average value was associated with that of the control.