Field capacity in rootable soil space

The field capacity (FK) of a soil or the individual soil horizon is the amount of water that it can hold back against gravity after sufficient saturation (according to convention for suction voltage pF >= 1.8). It is expressed in mm and calculated for the respective width of a horizon, then added and classified to a depth of 100 cm or the rootable floor space (dB). The method represents the representative FK of the respective depth level.土壤或单个土壤发生层（soil horizon）的田间持水量（field capacity，FK），指其在充分饱和后，按照行业通用惯例，当土壤水吸力对应的pF值不小于1.8时，所能持留以对抗重力的水分含量。该指标以毫米（mm）为单位，先针对单一层位的相应厚度完成计算，随后将各层结果累加，并按100厘米深度或可生根土层（rootable floor space，dB）的范围进行分类。本方法可表征对应深度层级的代表性田间持水量。