干旱区生态环境知识资源中心

Surface soil heat flux (G(0)) is an indispensable component of the surface energy balance (SEB) and is important for estimating instantaneous surface evapotranspiration (ET). The plastic mulch is laid on the cotton field for reducing soil evaporation and economizing water resource in arid area in Xinjiang Autonomous Prefecture of northwest China. The mulch affects soil thermal conduction, which has an important impact on G(0) estimation. In the present study the G(0) under mulch and bare soil between two mulches were calculated by the thermal conduction equation, respectively. The results show that the hourly G(0) under mulch is smaller than G(0) for bare soil both in daytime and nighttime. The mulch not only hinders energy into soil in daytime but also reduces soil heat loss in night. G(0) under mulch decreases quickly since July, while G(0) over bare soil decreases slowly. That's because the drip irrigation under mulch makes soil moisture increasing and the shallow soil temperature varies slowly since July, which decrease the soil thermal conduction. The mulch has little effect on daily G(0), as G(0) under mulch are nearly same as that for bare soil.