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Ningxia University (2020)

Study on the Lower Limit of Soil Moisture of Jujube Trees on Sandy Land in the Arid Zone of Central Ningxia

李晨

Titre : Study on the Lower Limit of Soil Moisture of Jujube Trees on Sandy Land in the Arid Zone of Central Ningxia

Auteur : 李晨

Grade : Master’s Theses 2020

Université : Ningxia University

Résumé
In this paper,the young jujube trees in the old sand belt in the central arid zone of Ningxia were taken as the research object.In view of the problem that the lower limit of soil moisture of the old jujube trees in the arid belt in the central arid zone of Ningxia was not clear,on the basis of the optimal crown width of 60cm,Through setting different irrigation upper limits,carrying out field simulation experiments on issues such as unclear soil moisture lower limit,using different depth geometers,time domain reflectometer(TDR),ruler,vernier caliper,oven,earth drill,aluminum box and other experimental instruments,By setting up soil temperature experiments at different depths and different distances inside and outside the greenhouse,observe soil temperature,soil moisture content,jujube tree growth characteristics and other indicators during the test period,and use icon comparison method,difference analysis,regression analysis and other mathematical methods to study The change trend of soil temperature at different depths,the relationship between the temperature inside and outside the shed,the change trend of soil moisture content,and the influence of different irrigation upper limits on the growth characteristics of jujube trees are based on the combination of daily water consumption and moisture content of jujube trees The method of determining the lower limit of soil moisture of jujube tree mainly draws the following conclusions :(1)The change trend of soil temperature under different treatments and different depths in a day is basically the same,and it shows a trend of first rising and then falling in a day.The highest temperature and the lowest temperature of different treatments appear at the time of 16 points and barrels in sand treatment At 4 points of bare planting treatment,the average temperature decreased with the increase of depth in the four treatments,and the whole showed "field pressure(field pressure sand treatment)>barrel pressure(barrel pressure sand treatment)>Tian bare(field bare Ground treatment)>barrel bare(barrel planted bare ground treatment)trend,the coefficient of variation decreases with increasing depth ;the use of cooling measures has no effect on the correlation between deep soil temperature,only the shallow layer temperature ;The relationship of soil temperature using different margins and different depths is:y=0.72x+7.58,and the model has certain accuracy after testing.(2)For the soil moisture content,with the increase of depth,the moisture content shows an increasing trend,and the extremely poor moisture content shows that the shallow layer(0~20cm)is larger than the deep layer(20~40cm)

Mots clés : jujube tree ;arid zone in central Ningxia ;old sandy land ;lower water limit ;soil temperature ;

Présentation (CNKI)

Page publiée le 31 mars 2022