Can Nonexchangeable Potassium be Differentiated from Structural Potassium in Soils？

Nonexchangeable K （NEK） is the major portion of the reserve of available K in soil and a primary factor in determining soil K fertility. The questions of how much NEK is in soils and how to quantify total NEK in soils are so far still unclear due to the complicated effects of various minerals on K fixation. In this study, the NEK in 9 soils was extracted with sodium tetraphenylboron （NaBPh4） for various time periods longer than 1 d. The results showed that the NEK extracted by NaBPh4 gradually increased with time, but showed no more increase after the duration of extraction exceeded 10 20 d. As the temperature increased from 25 to 45 ~C, the duration to obtain the maximum extraction of NEK was reduced from 20 to 10 d, and the maximum values of NEK released at both temperatures was almost the same for each soil. The maximum NEK （MNEK） of the 9 soils extracted by NaBPh4 varied from 3074 to 10081 mg kg-1, accounting for 21% 56% of the total soil K. There was no significant correlation between MNEK released by NaBPh4 and other forms of K, such as NH4OAc-extracted K, HNO3-extracted K and total K in soils, which indicates that NEK is a special form of K that has no inevitable relationship to the other forms of K in soils. The MNEK extraction by NaBPh4 in this study indicated that the total NEK in the soils could be differentiated from soil structural K and quantified with the modified NaBPh4 method. The high MNEK in soils made NEK much more important in the role of the plant-available K pool. How to fraetionate NEK into different fractions and establish the methods to quantify each NEK fraction according to their bioavailability is of great importance for future research.

Nonexchangeable K (鞍部) 在决定土壤 K 富饶是在土壤和一个主要因素的可得到的 K 的储备的主要部分。多少鞍部在土壤并且怎么确定的问题在土壤总计鞍部是到目前为止静止的由于 K 上的各种各样的矿物质的复杂效果不清楚固定。在这研究，在 9 土壤的 NEK 与钠 tetraphenylboron 被提取(为比 1 d 长的各种各样的时间时期的 NaBPh 4) 。结果证明 NEK 由逐渐地与时间增加的 NaBPh 4 提取了，但是在抽取的持续时间超过了 10-20 d 以后，显示出没有更多的增加。当温度从 25 ～ 45 °C 增加了，获得鞍部的最大的抽取的持续时间从 20 ～ 10 d 被减少，并且最大值在两温度释放的鞍部珍视几乎为每土壤的一样。NaBPh 4 提取的 9 土壤的最大的鞍部(MNEK ) 为全部的土壤 K 的 21%-56% 从 3 074 ～ 10 081 mg kg −1, 财务变化了。在 NaBPh 4和 K 的另外的形式释放的 MNEK 之间没有重要关联，例如 NH 4在土壤的 提取OAc 的 K ， HNO 3-extracted K 和全部的 K ，它显示鞍部是没在土壤有不可避免的关系到 K 的另外的形式的 K 的一种特殊形式。由在这研究的 NaBPh 4 的 MNEK 抽取显示在土壤的全部的鞍部能被区分开来与土壤结构的 K 并且与修改 NaBPh 4 方法确定了。在土壤的高 MNEK 在植物可得到的 K 水池的角色使鞍部更重要。怎么到进不同部分的分别鞍部并且建立方法确定每鞍部部分为未来研究根据他们的 bioavailability 是很重要的。