设施土壤水分扩散率变化特征

Variation characteristics of soil water diffusivity in greenhouse soil

为了观察设施栽培条件下土壤水分扩散率的变化,更好地实现设施土壤水肥管理以及有效地防治设施土壤次生盐渍化,采用水平土柱法及模拟分析方法,研究了设施土壤0～60 cm土层水分扩散率变化特征.结果表明:设施土壤的水分扩散率变化于0.02～3.78 cm2/min.水分扩散率存在一定的差异性,设施土壤在20 cm<h≤40 cm土层时最大,40 cm<h≤60 cm土层时最小;与同层次的露地土壤相比,设施土壤水分扩散率均较大;各层土壤水分扩散率与体积含水率之间呈指数关系,极具有统计学意义(P<0.01).波尔兹曼参数与体积含水率之间呈二次函数关系,在0<h≤20 cm土层,当体积含水率大于0.43 cm3/cm3时,设施土壤波尔兹曼参数小于露地土壤;当体积含水率小于0.43 cm3/cm3时,设施土壤波尔兹曼参数大于露地土壤.而在20 cm<h≤60 cm土层,设施土壤波尔兹曼参数均大于同层次露地土壤.

In order to clarify the change of soil water diffusivity and achieve better management of greenhouse soil and fertilizer as well as combat the secondary salinization of the soil, the variation cha- racteristics of soil water diffusivity in 0 〈 h≤60 cm depth greenhouse soil were studied by using the horizontal soil column method. The results showed that the soil water diffusivity varies from 0.02 to 3.78 cm2/min in that soil. The soil water diffusivity depends on the depth of soil. For example, the highest soil water diffusivity occurs in 20 cm 〈 h ≤40 cm soil layer, while the lowest in 40 cm 〈 h≤60 cm layer. Meanwhile, the soil water diffusivity in every layer in the greenhouse soil is higher than in the open field soil. The relationship between soil water diffusivity and soil water content in every soil layer was an exponential function, and the correlation factor is in significance level （ P 〈 0.01 ）. The relationship between Boltzmann parameters and soil volumetric water content in every soil layer presents a quadratic function. In 0 〈 h ≤20 cm soil layer, when the volumetric water content is greater than 0.43 cm3/cm3 , Boltzmann parameters of the greenhouse soil are less than the open field soil; howev- er, when the volumetric water content was lower than 0.43 cm3/cm3 , Boltzmann parameters of the greenhouse soil are greater than the open field soil. In 20 cm 〈 h ≤60 cm soil layer, Boltzmann param- eters of the greenhouse soil are all greater than the open field soil.