通常测定土壤含水率W和干容重γ_d值时,假定用容积为200立方厘米的环刀,取原状土重为g克,湿容重γ可以口算出来,即γ=g/V=g/200,但是土壤干容重(γ_d)和含水率(W)在现场进行计算就不太方便。下面介绍一种使用方便的专用计算尺可解决这个问题。根据干容重和含水率计算公式可整理成下式: Usually when measuring the soil moisture content W and the dry bulk density γ_d value, suppose that a ring cutter with a volume of 200 cubic centimeters is used, and the undisturbed soil weight is taken as g, and the wet bulk weight γ can be calculated by mouth, that is, γ=g/V=g/200, However, it is inconvenient for the soil dry weight (γ_d) and moisture content (W) to be calculated in the field. The following describes an easy-to-use dedicated slide rule to solve this problem. According to the formula of dry bulk density and moisture content, it can be organized into the following formula: