Genesis of Shallow Subsurface Drip Irrigation (S3DI)

Yield, economics, and management decisions for corn, cotton, and peanut row crops using deep subsurface drip (SSDI) and surface drip irrigation (SDI) systems led to the use of shallow subsurface drip irrigation (S³DI). With SSDI there was little or no yield difference with all three row crops between 100 and 75% irrigation rates implying a possible 25% water savings. The greatest management problem was the repair of SSDI tubing due to biological or mechanical damage. Tubing damage required the manual digging of each individual incident. The extent of labor prompted the possibility of laying drip laterals on the soil surface (SDI) where drip tubing could be easily serviced. Further research showed that laying drip tubing on the soil surface, during years of less than adequate precipitation, had yield potentials over 2, 3, and 7 times greater than nonirrigated crops for peanut, cotton, and corn, respectively. Chemical treatment of SDI tubing with registered pesticides for peanut did not result in less tubing damage but burying the tubing 3 to 5 cm below the soil surface reduced rodent damage to less than 5 holes/ha per year. The S³DI was easy to install and remove and reduced rodent damage so that drip tubing could be used one year and possibly longer. Further research showed that S³DI can be used economically in cotton and corn for one year during drought years. During a 6-yr trial, removing old and reinstalling new tubing between the 3^rd and 4^th year, irrigated cotton, corn, and peanut rotations had a $2658/ha net revenue increase compared with nonirrigated regime using the same crop rotation. Therefore, S³DI could be recommended for small fields of corn, cotton, and peanut (or other row crops) where overhead sprinkler systems may be cost prohibitive.