渭北黄土高原核桃林地的土壤水分特征

 水分是制约黄土高原地区生态环境恢复和经济发展的主要限制因子。研究黄土高原土壤水分变化规律,有着极其重要的科学和实际意义。采用随机设计,实地试验的方法,对渭北黄土高原核桃林下土壤水分状况及其变化规律进行了研究。结果表明:黄土高原核桃林地土壤蒸发量与月均温呈正相关关系。土壤含水量随时间的变化,主要受降水量和土壤蒸发与植被蒸腾耗水的影响。黄土高原核桃生长期的土壤水分季节变化,分为3个阶段:春末夏初土壤水分强烈消耗期(5—6月)、雨季土壤水分补充期(7—10月)和冬春土壤水分缓慢积累期(11月至翌年4月)。土壤含水量的季节性变化,与降水量的季节性变化密切相关。核桃林下的土壤贮水量,以8月份最大,6月份最小;耗水量在7月份最大,4月最小。4—7月处于水分亏损状态,而8—10月随降雨量增加,土壤水分便得到补充。水分调控不仅能不同程度地提高土壤贮水量,而且对水分亏损有一定缓解。各灌水处理下的土壤耗水量均有一定程度增大,而覆膜、覆草和修剪下的土壤耗水量,则有一定程度的降低。综合起来可以看出,覆膜、覆草、中等以上程度修剪、4月和6月分别灌水225kg和225kg等5种处理效果较佳,尤其是覆膜效果最好,不仅显著提高了土壤含水量和降低了土壤耗水量,促进了果实的生长发育,而且成本低廉,易于获得,使用方便。建议在黄土高原经济林丰产栽培中推广作用。

Soil moisture characteristics of walnut forest land in Weibei Loess Plateau

Water is a crucial limiting factor for the eco-environmental restoration and economic development in the Loess Plateau. That has practical and scientific significance to study the dynamic law of soil moisture. Based on random design and field experiments, the soil moisture condition and its changing law of walnut forest land were studied. The results showed that soil evaporative capacity of walnut forest land was positive correlation to average temperature of month. Precipitation, soil evaporation and plant transpiration were the primary factors affecting soil moisture which variation with time. The seasonal change of soil moisture in growing period of walnut was divided into three stages, excessive consume period in late spring and beginning summer (from May to June), supply period in rainy season (from July to October) and slow accumulation period in winter and spring (from November to April in next year). The seasonal change of soil moisture had closed correlation to seasonal change of precipitation. The water amount of soil in walnut forest is the highest in August and lowest in June. The water consume amount of which is the ighest in July and lowest in April. As to soil moisture profit and loss, it is in a deficient condition from April to July, and supplemented from August to October with rainfall increasing. Soil moisture could be improved and water scarcity could be decreased in a certain degree through water regulation. To amount of soil moisture consume, which was increased under different irrigation treatments, while decreased in a certain degree under covering membrane, covering grasses and pruning. In a word, the effects of covering membrane, covering grasses, pruning in a moderate level and irrigation (225?kg in April, 225?kg in June) were better than others. Especially the effect of covering membrane was the best, not only soil moisture was increased, the exhausting was increased and the growth of development was promoted, but also cost of which was cheap, gained easily and used expediently. It was suggested that the measure of covering membrane should be popularized in high yield cultivation of cash forest in loess plateau.