线源滴灌土壤湿润均匀性的影响因素试验研究

线源滴灌设计中,滴灌管出流均匀性与土壤湿润均匀性有本质不同,前者仅仅是后者必要的基础,但是要保证线源滴灌土壤湿润均匀性,还需要考虑滴头间距、滴头流量、滴水量和土壤质地的差别。对影响线源滴灌土壤湿润均匀性的主要因素进行了试验研究。试验中所用土壤为沙土和沙壤土;滴头间距为30 cm和50 cm;滴头流量为0.3~4 L/h;滴水量为10~25 L不等。试验表明,沿滴灌管方向的土壤湿润均匀度取决于湿润区的交汇程度,而湿润区的交汇程度又取决于土壤湿润区水平运移宽度和滴头间距。沙土沿滴灌管方向的土壤湿润均匀度随滴水量的增大而显著增大,沙壤土的相应指标则随滴头流量的增大而增大。土壤湿润均匀度随滴头间距的增大而减小。线源滴灌设计时,粘粒含量较少的土壤应该有一定的设计湿润深度和较小的滴头间距才能保证其湿润均匀度满足设计要求。研究结论对完善滴灌技术设计理论有帮助。

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

Field experiments were conducted to investigate the factors 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 30 cm to 50 cm,dripper discharge varying from 0.3 L/h to 4 L/h,and dripping water volume being in the range of 10~25 L.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 soil 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 is little mucous,a certain infiltration depth and small drippers spacing are necessary in the design of LSDI to ensure the USM.The results of this study are useful to the design of drip irrigation system.