LAUSR

Discharging of moisture and salt from unsaturated soil has always been a difficult problem. Therefore, a laboratory experiment in unsaturated soil, under drip irrigation, on subsurface drainage and soil desalination through subsurface drainage pipes (SDP) was conducted for using soil flume, where artificial macropore flow tubes (MFT) were deployed and connected to SDP. We conducted seven different deployment treatments of the artificial MFT, including four deployment tube densities (0, 3, 4, and 5) and two deployment arrangements (curved and straight). The results showed that no flow was observed in the SDP under the base treatment without MFT, increasing flow rates to 9.71 L, 10.7 L, and 12.3 L under the three straight line treatments and 7.81 L, 9.81 L, and 11.2 L under the three curved line treatments. Water content in both the upper and lower soil layers was almost uniform in the treatments with MFT, and an overall desalination trend was observed; the average desalination rate of curved MFT treatments was lower than that of the straight MFT treatments under the same MFT density. The findings serve as the foundation for future studies on drainage and desalination in unsaturated soil and facilitate the design of tile drainage under drip irrigation.