| Plastic film coverage is widely used in arid and semi-arid areas due to its advant ages such as increasing temperature,maintaining moisture,and increasing production.A large number of researches focus on the coverage of dryland agriculture.In recent years,the problems of climate aridity and soil desiccation have coexisted with the rap id development of regional arid agriculture and forestry,and the regional ecological en vironment has been deteriorating.Therefore,to explore the migration patterns of soil water,heat and salt covered by black and white film throughout the year,provides ba sis for the regulation of soil moisture,heat and salt with regional arid film covering,also provides reference for the annual continuous film covering in ecological economic forests,and is of great significance to regional arid agricultural and forestry producti on and ecological construction.In this study,the field film mulching data with bare lan d(CK),black film(BF)and white film(WF)mulching were used to explore the characteri stics of soil water-heat-salt under different film mulching from July 1st,2015 to June 30 t h,2017 at Mizhi in the north of Shaanxi Province,and soil water,heat and conductivity at 0~150 cm depth were observed by GS3 instrument with CK,WF and BF mulching.and set up on the same level terrace 10 m soil column was to simulate the dry soil layer of jujube forest.The results indicated that:(1)Black film can increase the surface soil moisture(0~15 cm),and at the depth of 15-30 cm white film has higher soil moisture than black film,but there is no difference between them at 0-150 cm soil layer.In the crop growth period,soil water storage with film coverage increased by 60.8 mm compared to CK,and soil water potential at 0-15 cm soil layer with WF and BF treatment were 68%(p<0.05),91%(p<0.05)higher respectively than CK.In non-growth period,loss of soil moisture with film covering was 21.1 mm less than that with CK,WF and BF treatments were 171%(p<0.05)and 157%(p<0.05)higher than CK in mulched soil.(2)Film covering increased soil surface temperature significantly,and the daily temperature difference near the surface with WF was greater than that with BF.within 0-30 cm soil layer,during the growth period the average accumulative soil temperatures with WF and BF treatments were 3989 and 3852 °C,which were 421.18 °C and 284.24 °C higher than that with CK,during the non-growth period the accumulative soil temperature with the two films was 2657 °C,which was 440 °C higher than that with CK.Within the 30 to 150 cm soil layer,the accumulative soil temperature with WF and BF during the growth period was 130 °C higher than that with CK,and was 209 °C higher during the non-growth period,and the negative accumulative soil temperature with WF and BF was 152 °C higher than that with CK during the non-growth period.The soil temperature below 30 cm with WF and BF did not change significantly in each soil layer.At the depth of 0-150 cm,there was no significant difference in annual average soil temperature with WF and BF,which was 1.3 °C higher than CK(p<0.05).During the non-growth period,soil temperature was significantly increased with film covering,with high temperature WF shortened the freeze-thaw time by 8 days compared with BF,and WF was more conducive to soil thawing and warming in early spring.(3)The surface soil salinity was high with three treatment.At 0-30 cm salt was BF>WF>CK,at 30-50 cm salt was WF>BF>CK,and there was no difference in salt with three treatments below 50 cm.The variation of salt at 0~5 cm soil layer was similar,which was the same at 0~15 cm.The variation at 0~5 cm with film covering from April to June was the largest and 65.5% higher than that with CK.The variation with film covering at 0-15 cm from October to March was the highest,which was 17.3% higher than that with CK.In water transition period the variability with film-covering was greater than that with CK.The soil salinity under film covering was high in the surface,and the annual variation was stable.The salt content was low and there was no tendency for soil salinization.(4)The effect of film coverage on the recovery of deep soil moisture was clarified.Within two years,at 0-30 cm soil layer,soil moisture content with film coverage increased by 10.8%,and it decreased by 7.1% with CK.At 30-50 cm soil layer,film coverage increased by 8.4%,CK decreased by 6.2%.Below 50 cm,film coverage increased by 1.7%,CK decreased by 6.3%.In the non-growth period,the deep layer water recovery of the film-covered soil was obvious.The difference of the soil moisture content between film coverage and CK mainly existed at 200-600 cm soil layer.In the first non-growth period film coverage was 90% more than CK,and in the second non-growth period film coverage was 112% higher.soil moisture during the non-growth period under the film increased most at 600-1000 cm with an increase of 20%,and the dry layer of film covered soil was reduced by 140 cm.(5)It revealed the coupling effects of soil moisture and heat and salt,and analyzed the influence of meteorological factors on soil moisture changes.At 0~50 cm soil layer,there was a positive correlation between soil heat and moisture with the three treatments,and at 50~150 cm soil layer,there was a significant negative correlation between water and heat with the three treatments.The water and salt correlation with BF was the lowest at most soil layers.The correlation was extremely significant.Soil temperature and electrical conductivity with WF had the greatest effect on soil water content.Film coverage reduced the meteorological factors that affect soil moisture changes,enhanced the correlation between soil moisture and atmospheric temperature,eliminated the consumption of soil moisture by wind speed,and reduced the impact of environmental humidity on soil moisture.(6)Using actual data,the HYDRUS-2D model parameters were determined by the localization rate,the appropriate simulation area and boundary conditions were determined,and the two-dimensional simulation of the moisture,heat and salt transport under the ridge-covered and no-irrigation condition was well achieved. |
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