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华北地区在土壤水分问题上,据我们估计,存在着五种情况:第一种情况是在秋耕时期耕层的土壤水分是适宜于耕翻和耙耘的。在耕翻和耙耘的适当时,冬季土壤水分不但不丢失反而在春季开冻时剖面上部有不同程度的增加,冬季土壤水分结冻在20—50厘米,可是在解冻后随着气温的上升和干风的到来(约在2月下旬或3月上旬),土壤水分蒸发的丢失,就使有些年份的春季下种出苗遇到困难,特别是棉花、小米和玉米的下种和出
In North China, on the issue of soil moisture, we estimate that there are five situations: The first case is that the soil moisture in the plow layer is suitable for tilling and raking during the autumn plowing period. In plowing and raking the appropriate time, winter soil moisture is not only not lost, but in the spring when the upper part of the profile has different degrees of increase in winter soil moisture freezing in 20-50 cm, but after thawing as the temperature rise And dry wind (about late February or early March), the loss of soil water evaporation has made it difficult to plant seedlings in spring in some years, especially under cotton, millet and maize