紫色水稻土钾有效性和钾释放的研究

紫色水稻土全钾含量属中等水平，速效钾属中等偏下水平，土壤对钾素的供应总体不足。作物吸收的钾，矿物钾占76.95％，速效钾和缓效钾仅占10.81％和12.24％。土壤矿物钾释放随时间的延长逐渐下降，随土壤颗粒粒径的下降显著增大，在80分钟时，释放量仍高达08～8.8mgkg-1.min-1，80分钟内的累积释放量为土壤缓效钾的1.5～2.0倍;土壤速效钾的形成随时间的延长逐渐趋向稳定。不同土壤矿物钾的释放顺序和土壤速效钾形成顺序的不一致性，是由它们的机理和土壤性状综合造成的，但是，Elovich方程都能较好地拟合土壤矿物钾的释放过程和土壤速效钾的形态过程，方程参数b值能反映过程进行的速度。

POTASSIUM RELEASE AND ITS AVAILABILITY IN PADDY SOILS DEVELOPED FROM PURPLE SOILS

There are medium contents of total K and lesser medium contents of available K in the paddy soils developed from pruple soils so that soil K is not sufficient for potassium requirement of crops in short. Mineral K accounts for 76. 95% of potassium uptaken by crops, while slowly available K and available K only accounts for 12. 24% and 10. 84%, respectively. The release of mineral K in the soils gradually decrease with prolonging of time and significantly increase with decreasing of size of soil particle. The accumulative releasing capacity of mineral K during 80 min is 1. 5-2. 0times of slowly available K, and releasing capacity in 80 min can reach 0. 8-8. 8 mg/(kg.min). The formation of soil available K may tend towards constant with extending of time. The inconsistency of sequences of releasing capacity of mineral K and formating capacity of available K in various soils insults from their mechanisms and soil properties. The releasing proccesses of mineral K and the formalating proccesses of available K can fit by the Elovich equation, in which b values can express the rate of these proccesses.