Soil Moisure Dynamics And Water Consumption Characteristics Of Farmland In Mu Us Sandland

The study area is located in Hailiutu River catchment in Mu Us sandland with shallow groundwater level,soil salinization and fragile ecological environment.The shortage of water resources has caused a great impact on development of local agriculture and animal husbandry.Based on the field monitoring data,including soil moisture,soil water potential,crop growth traits and weather data,and combining with the theoretical knowledge by studying Mu Us sandland changes of soil moisture,crop evapotranspiration rule and influencing factors,the change of crop growth stage was simulated by using Logistic growth curve model of spring maize growth traits（height,LAI）,the model can reflect spring maize LAI dynamic in the whole growth period,which providing for local agricultural production and management.The main results are as follows:According to the soil moisture danamic,the soil profile was separated into three soil moisture regions.The relative stable layer was acted as“underground reservoir”,which providing water supply for crop.The changes of soil water storage could be divided into dissipating stages and reserving stages.The crop height and leaf area index（LAI）of spring maize during the growth period were conformity with the Logistic curve with the rule of“slow-quick-slow”.According to the normalized model,which was based on the relative leaf area index and≥10℃accumulated temperature by the establishment of logistic curve,the correlation coefficient amounted 0.99.We can get the reference crop evapotranspiration,ET₀was estimated to be 623.6mm in the whole growth season of 2013.The single crop coefficients for the region were 0.27,1.14 and 0.55 during the initial stage,the mid-season stage and the late-season stage,respectively.In the whole growth season of 2013,the total evapotranspiration of maize was estimated to be 516.3 mm by adopting the single crop coefficient.In the early growth stage,the ratio of soil evaporation to water consumption（E/ET）was about 71%,and with the crop growth gradually decreases,in the development stage and medium stage was 15.53%and 6.64%,respectively.Soil evaporation had a good relationship with crop coverage:when leaf area index（LAI）<3,E/ET began to decrease rapidly with the increase of LAI;when LAI≥3,with the increase of LAI,E/ET decreased more slowly.