Information on the release of potassium (K) reserves in soils can improve K-fertiliser management. The purpose of this study was to investigate the available K-release capacity of soils and its relationship with plant responses in three soil orders. Six consecutive ryegrass cultivations were conducted on nine soil samples from surface (0–30 cm) horizons of Vertisols, Alfisols, and Inceptisols of three sites with different temperature and precipitation under greenhouse conditions. The K release was investigated using 0.2 M sodium tetraphenylboron extractant during 0.2–144 h. The cumulative release of K ranged within 243–895 mg kg–1 at 0.2 h and 620–1788 mg kg–1 at 144 h. Kinetics of K release from soils at two time intervals (0.2–2 and 2–144 h) were described well by power function and pseudo second-order equations. The growth of ryegrass was somewhat stunted after six consecutive cultivations. Significant correlations were observed between dry matter and K uptake of ryegrass. The parameters of the best fitted kinetic models were significantly correlated with plant responses, especially the uptake of K by ryegrass.

中文翻译：

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伊朗部分钙质土壤原生储备钾的释放特征及其与黑麦草（Lolium perenne L.）产量和吸收钾的关系

有关土壤中钾 (K) 储量释放的信息可以改善钾肥管理。本研究的目的是研究土壤的可用钾释放能力及其与三个土壤等级中植物反应的关系。在温室条件下，对来自三个不同温度和降水的三个地点的 Vertisols、Alfisols 和 Inceptisol 的表面（0-30 厘米）地层的九个土壤样品进行了六次连续的黑麦草栽培。使用 0.2 M 四苯基硼钠萃取剂在 0.2-144 小时内研究了 K 的释放。K 的累积释放范围在 0.2 小时时为 243-895 mg kg-1，在 144 小时时为 620-1788 mg kg-1。通过幂函数和伪二阶方程很好地描述了在两个时间间隔（0.2-2 和 2-144 小时）从土壤中释放 K 的动力学。连续种植六次后，黑麦草的生长有些受阻。在干物质和黑麦草的钾吸收之间观察到显着的相关性。最佳拟合动力学模型的参数与植物响应显着相关，尤其是黑麦草对钾的吸收。