四川洪雅几种退耕还林模式土壤钾素的动态研究

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。

A Study of Dynamics of Potassium in the Soil of Several Defarming-and-reafforestation Patterns in Hongya County of Sichuan Province

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.