一般玉米田都进行3～4次中耕培土,但无论几次中耕,都不宜培土过深,否则会导致减产。培土过深的害处是:一是会使根系通气不良;二是不利于提高地温;三是茎基部的叶片及叶鞘易被埋在土壤中,减少叶片光合作用;四 General corn fields are 3 to 4 times in cultivating soil, but regardless of several times in cultivating, it is not too earth too far, otherwise it will lead to cut. The harmful effects of excessive soil preparation are as follows: First, the root system will be poorly ventilated; Second, it is not conducive to raising the ground temperature; Third, the leaves and sheaths at the base of the stems are easily buried in the soil to reduce photosynthesis;