印度发明了一种能决定何时需要灌溉的使人感兴趣的方法,尽管用于指导高产灌溉尚不够灵敏,但是,这种方法简单、方便。在地里挖一个一米见方,一米深的坑。去掉约5%的土,换上沙土,将沙土和原来的土混合后回填到坑里,然后种上植物。当坑里的土持水量低于田间后,在田间的植物表现出枯萎的前两三天,种在坑里的植物就表现出枯萎的征兆,从而告诉农户该进行灌溉了。 India has come up with an interesting way of deciding when irrigation is needed. Although it is not sensitive enough to guide high-yielding irrigation, it is simple and convenient. Dig in the ground a one meter square, one meter deep pit. Remove about 5% of the soil, replace the sand, the sand mixed with the original soil back into the pit, and then planting plants. When the amount of soil in the pits is lower than in the field, plants planted in the pit showed signs of wilting two or three days before plants in the field showed signs of wilting, telling farmers what to do for irrigation.