Study On The Spatial Variability Of Soil Moisture Of Drip-irrigated Under Plastic Mulch In Cotton Field

Techniques of drip irrigation with plastic film cover in cotton field, which combines drip irrigation and the plastic film cover of the planting cotton, is a controlled partial irrigation, according to relevant reports, compared with the regular surface irrigation, save water about 50%, save fertilizer about 20%, and increase production about 20%. With the shortage of water resource and energy and rising of labor cost, techniques of drip irrigation with plastic film cover in cotton field must achieve auto-irrigation, and realize intelligent irrigation. Monitoring and prediction of the soil moisture played an important role in the process implemented of the intelligentize decision-making system; because spatial variability of the soil moisture is objective reality, it is very important to study spatial variability of the soil moisture to the monitor points of realize intelligent irrigation system.Up to now, there are many research of the spatial variability of the soil moisture on the regular surface irrigation; on the contrary, there is less research on the sprinkler irrigation, and the study of the drip irrigation under plastic mulch in cotton field is rare. The characteristic that the partial irrigates decided that the results of forefathers' research can't be used directly, so the text study the spatial variability of the soil moisture of the drip irrigation under plastic mulch mode, which offers the reliable, accurate data for the intelligent irrigation system, and scientific guides the field irrigation. The research not only fills blank in the respect in Xinjiang and domestic, and further thinning the research in this field.This text uses mathematical statistics and Geo-statistics methods, taking typical field in the Xinjiang Production and Construction Corps, Div 8, 148 group and General group as an example, and analyzes the regularity of the spatial variability of the soil moisture, at the same time, construct structural model of the spatial variability. The important conclusion follows:1, Under the condition of different soil texture, space structure of the soil moisture of the drip irrigation under plastic mulch is different, the spatial variability of the soil moisture with the random factor of the clay loam is greater than the loam, space structure of 20～40cm layer soil moisture of the loam is more obvious, and 20～60cm layer of the clay loam is more obvious; the spatial variability of the 0～20cm soil moisture with the random factor is more obvious, and 20～60cm layer is weak.2, Under the differently dimension condition, dimension increases with sampling, the spatial variability that the random factor of 0～20cm layer of soil moisture brings is reducing gradually, with dimension increases, and relevance is reduced gradually, the space structural is more and more obvious; on the contrary, the spatial variability and relevance of the 40～60cm layer is obvious gradually, the space structural is worse and worse.3, Under the different growing stages condition, the total spatial variability of the 0～20cm layer soil moisture of drip-irrigated cotton under plastic mulch is reducing in earlier stages, increasing on later stages, on the contrary, 40～60cm layer is increasing in earlier stages, reducing on later stages, but 20～40cm layer gradually increases with growth of the cotton; during the growing stages in different vertical depth, the deeper layer of soil, the spatial variability is becoming obvious; relevant range is slight to change during the seedling stages and the florescence stages, on the contrary, relevant range is obvious to change at different layers during the budding stages and the bolls opening stages.4, Simple Kriging is superior to Ordinary Kriging for the 0～20cm layers soil moisture, on the contrary, Ordinary Kriging is superior to Simple Kriging for the 20～60cm layers soil moisture.