四川紫色水稻土钾的形态和固定

对四川盆地紫色水稻土钾的形态和固定的研究表明,矿物态钾占95％～98％,是土壤钾的主体;非代换态钾和代换态钾仅占0.6％～3.55％和0.49％～1.28％;水溶态钾含量在10.0mg/kg 以下。在施入的钾中,水溶态和代换态钾所占比例随施钾量的增加而下降,非代换态和矿物态则呈增加趋势。土壤固钾能力决定于土壤中蛭石、伊利石和萦脱石的含量。酸性紫色水稻土固钾能力明显低于钙质和中性紫色水稻土。在施钾量低时,钙质紫色水稻土固钾能力弱,但随着施钾量增加而显著增强。根据施钾量与土壤速效钾的关系,可计算土壤施钾量和评价其肥效。

MORPHOLOGY OF POTASSIUM AND ITS FIXATION IN PURPLE PADDY SOILY IN THE SICHUAN BASIN

Mineral potassium was shown to be the major component of soil K,accounting for 95%-98% of the total while non-exchangeable K and exchangcable K represented only 0.6%-3.55% and 0.49%-1.28% of the total.Water soluble K was negligible,being less than 10.0 mg/kg.In the K applied to the soil,water soluble and exchangeable K decreased with K rates while non-exchangeable and mineral K exhibited a rising trend. Potassium-fixing capacity of the soil depended on the contents of vermiculite,illite and montmorillonite in the soil.The rate of K fixation in acid purple paddy soils were substantially lower than in neutral or calcareous purple paddy soils.At low K rates, potassium-fixing capability seemed low.It steadily increased,however,with increasing K rates.Optimum K rates in various soils wcre estimatcd and their effects were evaluated based on the relationship between K rates and the content of readily available K in the soil.