我国北方地势高寒,气候干燥,水源不足,十年九旱。因此,如何作好耕耙保墒整地工作,是保证春播全苗的重要环节。多年来,群众创造出一套适合干旱特点的耙耢保墒、早耕塌墒和镇压提墒的“三墒”整地抗旱经验,实践证明效果良好。为什么“三墒”整地能保墒呢?每年七、八月份是多雨季节,除作物吸收外,大部分雨水渗入土中。9月以后,作物需水少了,气温下降,蒸发减少。经过秋耕,加上冬雪,此时土壤饱含大量水分。严冬季节由土壤表层向下开始冻结,表层大孔隙中凝成冰屑。春季一解冻,土壤返浆,此时顶凌耙地保墒。随着气温升高,土壤全部解冻,地表温差减小,水分由毛细管蒸发转为全面气态扩散,此时单靠耙耪不能控制土壤水分扩散,应将耙耢和镇压紧密结合起来。镇压后, Cold terrain in northern China, dry climate, lack of water, nine drought ten years. Therefore, how to cultivate harrow soil preparation work site is to ensure that the whole spring sowing an important part. Over the years, the masses have created a set of drought-tolerant characteristics of rake 耢 soil moisture, pre-tillage soil moisture and suppression of soil moisture to enhance the “three moisture” site preparation drought resistance experience proved to be effective. Why “three moisture” soil preparation can maintain moisture it? July and August each year is the rainy season, in addition to crop absorption, most of the rain infiltration into the soil. After September, crop water demand is less, temperature drops and evaporation is reduced. After autumn plowing, with winter snow, at this time the soil is full of water. Winter season began to freeze down from the surface of the soil, condensed into large pores in the surface of the ice debris. A spring thaw, the soil back to pulp, this top Ding rake moisture. As the temperature rises, all soil thaw, surface temperature decreases, the water evaporation from the capillary to a full gaseous diffusion, this time alone can not control the soil rake 扩 扩 扩 扩,,,,,,,, 应 应 应After the crackdown,