不同连续提取条件下土壤K素的释放速率

以 1mol· L-1HNO3 (85℃ )、2 mol· L-1HNO3 (2 0℃ )和氢质阳离子交换树脂恒温连续提取法 (2 0℃ ) ,利用 Elovich模型 ,结合生物吸 K试验 ,研究了不同连续提取条件下土壤 K素释放速率的差异及其与K素有效性的关系 .研究结果表明 :1mol· L-1HNO3 提取法的释 K速率 >2 mol· L-1HNO3 提取法的释 K速率 >氢饱和交换树脂提取法的释 K速率 ;氢质交换树脂和 2 mol· L-1HNO3 提取法结合 Elovich模型较理想地描述了土壤 K素的释放特性 ,拟合方程的相关系数均达极显著水平 (r=0 .956 * * - 0 .999* * ) ,土壤特征累积释 K量的计算值与实测值的标准差较小 (s=1.6 1和 3.52 ) ,且通过速率方程计算的土壤特征释 K速率与K素有效性指标 (速效 K、缓效 K、有效 K及黑麦草总吸 K量 )的相关性也较为密切 .因此 ,氢质阳离子交换树脂和 2 mol· L-1HNO3 提取法结合 Elovich模型可较好地描述土壤 K素的释放及其速率

The release rate of soil K under the condition of various successive extraction

The difference of soil K release rate under the condition of various successive extraction and the relation between K release rate and K availability were studied by use of Elovich model combining with the test of 1 mol·L -1 HNO 3(85 ℃), 2 mol·L -1 HNO 3(20 ℃) and H resin successive extraction(20 ℃) at constant temperature and pot exhausion of ryegrass. The results calculated by the Elovich rate equation showed that K release rates from 1 mol·L -1 HNO 3 extraction >those from 2 mol·L -1 HNO 3 extraction >those from H resin extraction. Elovich equations combining with the data of H resin and 2 mol·L -1 HNO 3 successive extraction could well described the release characteristics of soil K. The correlation coefficients of the equations reached most significant levels ( r =0.956 ** —0.999 ** ), and standard errors of specific K release capacities between the vaules calculated by the equations and those measured by both successive extractions were smaller( s =1.61 and 3.52). The specific release rates of soil K calculated by the Elovich rate equations were significantly correlated with the indices of soil K availability (the amounts of easily available K, nonexchangeable K, total available K in soils and K absorbed by ryegrass). So data of H resin and 2 mol·L -1 HNO 3 successive extraction combining with Elovich model could well describe the release and rate of soil K.