| This paper mainly studied the cover after autumn water freezing and thawing period and growth period of soil hydro-thermal salt migration effect.Test by using the mechanism,laboratory test and field data monitoring and model simulation analysis,the method of determination of the soil under different salinity is not frozen,pore water distribution and different soil water content for freezing process is not frozen water content.Analyzed the influence of NaCl on not frozen water content and the hysteresis phenomenon in the process of soil freezing and thawing,Set different mulching treatment measures,the system of study under the condition of surface coverage autumn water again when the spring sowing soil hydro-thermal salt distribution characteristics,the following water,heat,salt,and the response of crop growth and yield.at the same time,to cover annual autumn water conditions of soil water salt and heat movement SHAW model simulation,the main conclusions are as follows:(1)According to the experimental results,the higher the concentration of NaCl saturated solution was,the larger the unfrozen water content was,and the lower the freezing temperature was.Unfrozen water content changed to varying degree in different soils,and the unfrozen water content in soil was obviously higher than that in silt loam soil;saline soil frozen and thawed relatively slowly,and in the areas where freezing and thawing lagged behind obviously,with the concentration rising,the temperature range tended to decrease.(2)Autumn mulching could influence the soil temperature under each treatment within the spring maize growth period,as the mean of topsoil temperature after film mulching was the highest,but the topsoil temperature after straw mulching was lower than that without mulching,slowing the warming of soil in the spring and thus impeding the growth of crops sowed in spring;soil moisture after each treatment of mulching and autumn irrigation was higher than that of CK,moreover,for the soil water storage in both sowing period and growth period,the water conservation effects were sequenced as straw mulching>DM>CK.(3)All the average values of soil salinity after each treatment of mulching and autumn irrigation were lower than that of CK,with soil salinity of YZ being the lowest.;both grain and biological yields after mulching were higher than those of CK,with YZ showing the highest grain yield,and the grain yield of spring maize improved after both straw and plastic film mulching;the whole maize straw mulching(YZ)and crushed maize straw mulching of 0.9 kg/m2(F0.9)showed high yields and high economic coefficients.(4)SHAW model simulation of soil temperature is of high accuracy,can very good reaction change rule the day.Surface soil simulation error is deep soil slants big,but the overall simulation precision,reliability and rationality.For soil moisture content of the simulation,the simulation value of soil moisture content and the change law of soil moisture content measurement,surface soil simulation value higher than the measured values,the deep soil of analog value is closer to the measured values.The 0-120 cm soil layer,throughout the year for soil salinity simulation verification results slightly less,simulated values and measured values deviation slightly larger,straw mulching soil salinity simulation accuracy is slightly higher than the plastic mulching.(5)The synthetic SHAW model simulated the effects of different mulching methods on soil water and salt movement.The results showed that the best mulching method for the sand channel experiment field of Hetao irrigation area was straw mulching,and the coverage was 0.9kg/m2 best. |
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