Charateristics Of Soil Water And Heat Transport And Model Simulation For Maize Cultivation In Drylands Of Loess Plateau

Water is an important factor for Rain-fed agricultural region,especially on the Loess Plateau of China.This study investigated the change of soil water,temperature and water stress based on a two-year field experiment in semi-arid regions of northwest China(35?12'N,107?40'E)by comparison between ridge plastic film mulching cultivation(RP)and flat cultivation without plastic film mulching(FP)treatments,we simulated the change of soil water,temperature under FP and RP by Hydrus-1D and Hydrus-2D,respectively.(1)The results showed that the soil moisture in 30~60 cm soil layer significantly increased by approximate 44% between FP and RP treatments;Soil water storage in FP treatment in deep soil layer(100~160 cm)was significantly higher than that in RP treatment.Soil water storage(SWS)of 30~60 cm in RP treatment and furrow were higher about 20 mm than that in FP treatment throughout growth season,but SWS in 100~160 cm in RP treatment was lower about 25 mm than FP treatment.Soil temperature above 10 cm soil surface in RP-Ridge(RPR)was 2.01? and 1.91? higher than RP-Furrow(RPF)and FP treatment,respectively.RPF could well-catch the rain water from ridge and the water in furrow could supply the ridge by lateral movement with a certain time-lag.RP can improve soil water content and temperature,increase infiltration of rainfall,limit the deep infiltration during storm events,and avoid the "self mulching" phenomenon,which had great significance effects on maize growth.(2)Hydrus-1D can well simulate the soil water content for different soil layers during maize growing season.The soil water storage(SWS)in the top 0~10 cm layer varied significantly,and the variation changed smaller with increased soil depth.Precipitation(P)and Infiltration(In)had a positive effect on SWS in the upper soil layer;while soil evaporation(Es)and crop transpiration(Tp)showed negative effects.SWS in the 60~100 cm soil layer could be substantially affected by plant root uptake(RT),the SWS tended to be more stable in deeper soil layers(100~160 cm)for the less influence caused by Es,Tp,P/In and RT.The high SWS before sowing(initial SWS)had positive effect on the dynamic of SWS,which supplied water for root uptake and soil evaporation,thus preventing the plough pan to form of dry layer when drought occurred during early stage of maize growing season.Large evapotranspiration(ET)and low infiltration in soil depth of 30~60 cm(plough pan)would result in temporally dry layer especially during the early stage of maize growing season(drought period),which highlighted the sensitive layer and time for water stress during maize growing season.An effective tillage management such as deep plough or plastic film mulching is needed to avoid the form of drought layer and thus to improve maize production.(3)According to the result of Hydrus-2D,soil water and temperature transport from ridge to furrow under no rainfall;there only exited infiltration of precipitation to surface soil of furrow under limited rainfall,for the soil was unsaturated and effect of gravity was declined;but the infiltration was obviously under hard rainfall,and the soil water of ridge was supplied by the soil water of furrow with 0~60 cm layer.And because of the evaporation after rainfall,deep soil water of furrow would transfer to the upper layer,there was driving force for migration of soil water of ridge to furrow.