蔬菜保护地土壤对外源钾的固定特征研究

Characteristies of K+ fixation by the Vegetable Soils in Solar Greenhouses

对蔬菜保护土地壤的固钾特征进行了研究，结果表明土壤的固钾率随着土壤速效钾含量的提高和钾素施入量的增加逐渐降低．土壤用于保护地蔬菜栽培以后，速效钾含量明显提高，同时土壤对钾素固定率也随之降低．铵离子可以替代钾离子而被土壤粘土矿物固定，铵离子和钾离子等浓度存在时土壤的固钾率仅是钾离子单独存在时的二分之一，当这两种离子的浓度分别达到300．0μg·g-1时，施入土壤中钾素的固定率降低到50％以下，最低的只有27．7％。因此，在蔬菜保护地条件下，为避免钾素的淋失和土壤溶液浓度的提高，应提倡钾肥与铵态氮化肥分施和钾肥分次施用。

The characteristics of K+ -fixation by the vegetable soils in solar greenhouses were studied. The resultsshowed that K+-fixation rates or the soils deceased with the increase of soil available K and applied K+. Thecontents of available K were higher in the vegetable soils in the greenhouses than that in the openfield soils,consequently the K+ -fixation percentages were lower in the vegetable soils. NH4+coud be fixed by clays in thesoils as K+. The K+-fixation percentages deceased by hair with the addictional same concentration of NH4+in the solution. When NH4+, K+concentration tvers 300.0μg·g-1 separately, K+ -fixation percentages were lowerthan 50%, the lowest was 27.7%. Hence, for preventing the leaching of K+and increasing the K efficiency, it isrecommended that K fertilizer be applied in splits and separating with ammonium form fertilizer.