【摘要】 对四川洪雅四种退耕还林模式进行定位研究,分析各模式土壤中钾素的动态变化。结果表明:各模式在两土层中的速效钾含量较为丰富,缓效钾含量都较缺乏,故靠植被自肥作用是无法维护其他地力的,必须人为补充钾肥;各模式的水溶性钾在两土层的变化规律基本一致,从4月份开始下降,7月份达到最低峰,故在钾素大量消耗之前的2月~3月是钾肥施用的适当时期;就各模式而言,模式Ⅰ(光皮桦+牛鞭草模式)对土壤当季和长期供钾能力作用最佳,最对土壤各种形态钾素相互转化影响最好的一种模式。更多还原

【Abstract】 To understand dynamic changes of potassium in the soil of different Defarming-and-reafforestation patterns,four patterns were chosen as sampling spots in Hongya County of Sichuan Province during the two years.Research results have shown that rapidly available K is rich but slowly available K is scarce,which indicates that the natural fertility of vegetation cannot keep its land capability unless some manure is added.Dissolved K in the soil of four patterns begins to decrease from April and comes to the lowest level in July.Therefore,a suitable season for fertilization is between February and March.Betula luminifera+Hemarthria compressa is the optimum pattern for the current-season and long-term K supply ability,and is also the best pattern which affects the the conversion of the K of various forms in the soil.更多还原