|张 静1,2; 王 力1,2; 韩 雪1; 张林森3
|Source Publication||土 壤 学 报
0～100 cm 土壤含水量变异系数较大，土壤水分变化剧烈，作物根系的集中分布范围在0～80 cm 之间，
因此0～100 cm 土壤水分主要参与蒸散过程；晴天蒸散的累积量大于阴天，晴天和阴天的日均蒸散量分
别为4.5、3.8 m m d -1 ，相差0.7 m m d -1 。阴天蒸散开始的时间较晴天晚，阴天条件下的蒸散更易受到气
Evapotranspiration（ET）is a m ajor part of water balance and energy
balance，and is the m ain pathway of water consum ption in farm land ecosystem s. In X ianyang D istrict of
Shaanxi，the annual evapotranspiration accounts for about 90% of the annual precipitation. There are quite
a few m ethods for evaluating or m easuring evapotranspiration，such as eddy covariance，Bowen ratio and
m icroclim ate. Currently the eddy covariance m ethod is m ore widely used than the other two because it can
be used to m easure evapotranspiration continuously on an ecosystem scale，and to m easure sim ultaneously
various m eteorological factors and various com ponents of energy，as well，in m ost of the eddy-covariance-
related system s，which is conducive to analysis of relationships of various im pact factors with com ponents
of energy balance. The present study is oriented to explore basic laws of water m ovem ent in soils different in
land use，but under a sim ilar plant growth environm ent and also to find a scientific m ethod for estim ating
water consum ption in soil. 【M ethod】In order to explore laws of diurnal dynam ics of evapotranspiration and
its influencing factors in farm lands on loess tableland，with the help of som e soil water and conventional
m icrom eteorological observatory system s，the eddy covariance m ethod was used to analyze characteristics
of the evapotranspiration of the crops（winter wheat and spring corn）in the farm land studied during the
growing season（from A pril to O ctober）of 2013 and their influencing factors. 【R esult】Closure analysis
of energy balance in the studied area using the eddy covariance m ethod shows that the regression line was
0.54 in gradient and the determ ination coefficient R 2 0.80，both being in the ranges reported in m ost papers
in the literature. Soil m oisture is an im portant factor affecting evapotranspiration，and precipitation is
another. A fter a rainfall event，daily evapotranspiration would increase to a certain extent. Soil water content
in the 0～100 cm soil layer varied drastically with CV being quite high，while crop roots were distributed
m ainly in the 0 ～ 80 cm soil layer，so the soil water in the 0～100 cm soil layer was closely involved
in evaporation process. Cum ulative evapotranspiration was higher in a sunny day than in a cloudy day，
while evapotranspiration started later in a cloudy day than in a sunny day. The daily evapotranspiration was
4.5 m m d -1 on average in the sunny day and 3.8 m m d -1 in a cloudy day，with a difference being 0.7 m m d -1 .
M oreover，evapotranspiration in a cloudy day was m ore susceptible to the disturbance of m eteorological
factors. N et radiation was the m ain factor affecting evapotranspiration rate，regardless of weather conditions，
and the two varied in a sim ilar trend，but the latter lagged som ewhat behind the form er tem porally in variation
because it takes som e tim e for energy to flow. The regression equation for analysis of relationships between
evapotranspiration rate and its influencing factors in a sunny day does like：ET = 0.833R n + 0.513T a -
0.333v-0.486；and that in a cloudy day does like：ET = 0.858R n + 0.219V PD -0.001. Evapotranspiration
also varied drastically in process and intensity as affected by soil water regim e. 【Conclusion】The influence
张 静,王 力,韩 雪,等. 黄土塬区农田蒸散的变化特征及主控因素[J]. 土 壤 学 报,2016,53(6):1421-1432.
张 静,王 力,韩 雪,&张林森.(2016).黄土塬区农田蒸散的变化特征及主控因素.土 壤 学 报,53(6),1421-1432.
张 静,et al."黄土塬区农田蒸散的变化特征及主控因素".土 壤 学 报 53.6(2016):1421-1432.
Items in the repository are protected by copyright, with all rights reserved, unless otherwise indicated.