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Northwest A&F University (2017)

Vertical Regulation of Crop Root Zone Soil Moisture and Estimation of Evapotranspiration

周始威;

Titre : Vertical Regulation of Crop Root Zone Soil Moisture and Estimation of Evapotranspiration

Auteur : 周始威;

Grade : Master’s Theses 2017

Université : Northwest A&F University

Résumé
Partial root zone water stress was a new water-saving technology.The difference of soil moisture distribution on space was necessary for the implementation of water-saving effect.Soil moisture was a important factor that affected crop evapotranspiration.The spatial distribution of soil moisture also could affect the estimate crop evapotranspiration.This paper regarded spring wheat and spring maize wheat in Shiyang River Basin as the research object,and achieved the crop root zone soil water distribution in vertical direction by the way of controlling the upper bounds of water application,the lower bounds of water application and the scheming wetted soil layer depth in different growth periods.The objectives of this study were to(1)study the effects of vertical regulation of root zone soil moisture ;(2)study the optimization of irrigation schedule for spring wheat with RZWQM model in order to achieve maximum benefits of water-saving ;(3)study the effect of irrigation water on estimation accuracy of evapotranspiration of crop by comparing calculated value with measured value.Results showed that :(1)It can regulate soil moisture profile and effect the distribution of crop root system better by the control scheming wetted soil layer depth in different growth periods,which also can impact on absorption and utilization of soil water greatly.The acting position of vertical regulation of root zone soil moisture is 0 60cm layer.The soil moisture content and root length density of 40 60cm layer was affected significantly.The yield difference of different water treatment is small,but there is a big difference of irrigation among treatments.As a result,it can achieve water-saving and stable yield effects by regulating soil wetted depth in different growth stage of spring wheat.(2)RZWQM can be used to evaluate the effect of various irrigation upper limits and scheming wetted soil layer depth in different growth period on crop yield,irrigation amount and water use efficiency.The yield in different irrigation treatment is not obvious change compared with the needed irrigation rate.The effect of irrigation upper limit on irrigation rate was more remarkable than that of crop yield.The reducing of irrigation upper limit will increase the irrigation rate,thus improving the yield of spring wheat.The appropriate scheming wetted soil layer depth can effectively improve the utilization efficiency ofirrigation water,and achieve the purpose of water saving.Through regulating irrigation upper limit and scheming wetted soil layer depth in different growth period,it can save water saving and improve production of spring wheat.Considering the influence of the control factors on the yield,irrigation amounts and GIWUE,we choose 80% of field capacity as irrigation upper limit.And the optimal supply model of water is 30 cm,60 cm,50 cm and 70 cm of irrigation at seeding,jointing,heading and filling stages,respectively.(3)There were differences for the root zone soil water content and its spatial distribution under different irrigation water.Irrigation water can affect the estimation accuracy of evapotranspiration of crop in arid.FAO-56 can estimate evapotranspiration of crop accurately under low irrigation water treatment,however,the estimate accuracy decreased with the increase of irrigation water.The estimation error of evapotranspiration under high irrigation water was-14.13%.Relation between soil water content of the upper layer and soil water stress condition is close.The soil water stress coefficient was calculated with the average soil water content of part layer in the root zone,which can effectively improve estimation accuracy of evapotranspiration under high irrigation treatment in arid areas.The estimation error reduce to-9.97%.

Mots clés : spring maize; spring wheat; RZWQM; scheming wetted soil layer depth; irrigation water; evapotranspiration; regulation of soil water;

Présentation (CNKI)

Page publiée le 31 janvier 2018