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土壤容重是计算土壤重量的必须数据,对计算施肥量和灌溉用水量都是基础数据。土壤体积乘以容重,即得土重。根据土重和测得的土壤养分含量,可以算出单位面积内一定土层深度内的土壤养分总含量,然后按作物生育需要的养分量,决定施肥量。同样,可以根据土壤重和测得的含水量,算出单位体积内的土壤含水量,然后根据作物生育需要的用水量,决定灌溉定额。计算土壤总孔隙度,除容重外,还要有土壤比重的数字。土壤比重的大小因受矿物种类而异,变化幅度在2.3～2.9之间,一般是2.6～2.7,通常用2.65。计算总孔隙度的公式是:
Soil bulk density is the necessary data to calculate the soil weight, which is the basic data for calculating the amount of fertilizer and irrigation water. Multiplied by the volume of soil bulk density, that is soil heavy. According to the soil weight and the measured soil nutrient content, the total soil nutrient content within a certain soil depth per unit area can be calculated, and then the amount of fertilizer required for crop growth can be determined. Similarly, the soil moisture content per unit volume can be calculated from the soil weight and measured water content, and then the irrigation quota can be determined based on the amount of water needed for crop growth. Calculate the total soil porosity, in addition to the weight-bearing capacity, but also have the proportion of soil figures. The proportion of soil specific gravity varies depending on the mineral species, the range of variation between 2.3 to 2.9, usually 2.6 to 2.7, usually 2.65. The formula for calculating the total porosity is: