北方主要土壤钾形态及其植物有效性研究

NATIVE POTASSIUM FORMS AND PLANT AVAILABILITY IN SELECTED SOILS FROM NORTHERN CHINA

从北方12个省（市、自治区）选取了25个有代表性的土壤样品，将土壤中的钾按其存在形态计为水溶性钾、非特殊吸附钾、特殊吸附钾、非交换性钾和矿物钾。前三种形态钾的总和不超过全钾的2．0％．非交换性钾也仅占全钾的2．7％～9．4％，而全钾的89．8％～96．8％是以矿物态存在的。根据土壤中各形态钾含量，特别是非交换性钾含量分析，可以看出供试25个土壤的供钾能力按取土地点自西向东（西北－华北－东北）有明显降低的趋势。在连续耗竭情况下，不同土壤的植物净吸钾总量的差异十分悬殊，范围为96．3～793．5mg／pot。根据植物净吸钾总量的大小，将供试土壤的供钾能力分为极高、高、中、较低和低5个等级。其结果也表明供试土壤供钾能力控取土地点自西向东呈明显降低的趋势。耗竭条件下植物吸取来自土壤不同形态钾的比例相差很大。以来自水溶性钾的比例为最小．平均为3．1％；其次是非特殊吸附钾，平均为7．7％；再次是特殊吸附钾，平均为10．2％；来自非交换性钾的比例较大，平均为33．3％；来自矿物钾的比例最大，平均为45．7％。本研究区分了非交换性钾和矿物钾对植物吸收钾素的贡献，发现在耗竭条件下矿物钾是植物的重要钾源。

Twenty-five representative plower depth soil samples from 12 Provinces,Municipalities and Autonomous regions in major agricultural regions in northern Chinawere selected. Soil native potassium exists in 5 forms, namely water soluble K, non-specifically adsorbed K, specifically adsorbed K, non-exchangeable K and mineral K.Total potassium in the front 3 forms is less than 2. 0% of the total soil K. Non-exchangeable K accounts for 2. 7%~9. 4% of the total soil K, while mineral K accountsfor 89. 8%~96- 8% of the total soil K. According to the content of K in various forms,especially the content of soil non-exchangeable K, it is evident that potassium supplyingpower of the selected soils shows a general tendency of decrease from west to eastreglons (northwestern China -- northcentral Chlna -- northeasterri China j. Soilpotusslum deplet1on study was conducted in a pot experiment with successive plantingof corn seedling for 8~10 harvests. The 25 tested soils varied considerably in total netK absorption. wlth a range of 96. 3~793. 5mg/pot. In accordance with the amount oftotal net K uptake, potassium supplying power of the tested soils was divided into 5categories: very high, hlgh. medium. relatively low and low. In general, there was anotable tendency of decrease in soll K supplying power from west to east regions. Underdepletion condition and wlthout K application, the contrlbutions of various forms ofnative K to plant uptake varied significanUy in the order: water soluble K (with aaverage of 3. 1%) < non-specifically adsorbed K (average 7- 7%] < specifically adsorbed K(average 10. 2%) < non-exchangeable K (33. 3%) < mineral K (45. 7%). In this research,contribution of mineral K was differenciated from non-exchangeable K, and the resultindicated that mineral K contributed significantly to K uptake by plants.