在第一讲中,谈到水分是土壤组成成分之一。它在土壤中的含量,一般占土壤体积的15—35％。 没有水就没有生命。作物本身含有大量的水分,作物生长则需要更多的水分。一般作物的绿色体含有60—80％的水,而蔬菜、块根和块茎作物、瓜类等含水量高达90％以上。但作物一生中所消耗的水分与植物本身的含水量比较起来,其数量大得更是惊人。例如每生产一斤稻谷约需800斤水,一斤棉花约需360—650斤水,其它如玉米、小麦等禾谷 In the first lecture, it is mentioned that moisture is one of the components of soil. Its content in the soil generally accounts for 15-35% of the soil volume. There is no life without water. The crop itself contains a lot of water, crop growth requires more water. Green crops contain 60-80% of the water, while vegetables, tubers and tubers, melons and other water content up to 90%. However, the amount of water consumed during crop life is even more alarming than the water content of the plants themselves. For example, each kilogram of rice produced about 800 pounds of water, a pound of cotton about 360-650 pounds of water, other cereals such as corn, wheat and other cereal