Experimental Study on Factors Influencing Soil Moisture Uniformity under Linear Source Drip Irrigation

摘要

Field experiments were conducted to investigate the factors which are influencing soil moisture uniformity under linear source drip irrigation.The experiments involved different combinations of two soil types (sandy and loam soils),drippers spacing ranging from 30cm to 50era,dripper discharge varying from 0.3L/h to 5L/h,and dripping water volume being in the range of 10L～25L.The experimental results show that there is an essential difference between the uniformity of dripper discharge along the drip line and the uniformity of soil moisture in field (USM) in terms of the design of linear source drip irrigation (LSDI).The dominant factors of soil moisture uniformity include drippers spacing,dripper discharge,dripping water volume,and soil types.These factors should be taken into account in the design of LSDI in addition to the essential prerequisite factor that ensures the uniformity of dripper discharge along drip line.The uniformity of soil moisture along drip line (USMDL) depends on the overlapping of soil wetting patterns,which is further controlled by the width of soft wetting pattern and the drippers spacing.The USMDL for sand soil increases significantly with dripping water volume.In loam soil the USMDL increases with dripper discharge.The USM for both types of soils decreases with increasing drippers spacing along the drip line.If the soil contains high clay content,a certain infiltration depth and small drippers spacing are required in the design of LSDI to ensure the USM.The results of this study are useful to the design of drip irrigation system.