The Effect of Subsurface Drip Irrigation Combined with the Use of Pesticide to Prevent Dripper Clogging in Alfalfa Cultivation in a Semiarid Region

Given the scarcity of water resources in arid and semiarid regions, enhancing irrigation systems to minimize evaporation losses and improve transpiration management is paramount for elevating water productivity. This research aims to study the effects of applying subsurface drip irrigation, combined with the use of trifluralin, on preventing dripper clogging in alfalfa cultivation from 2019 to 2021 at the Ekbatan Station of Hamadan Agricultural Research Center, Iran. The study was conducted using a randomized complete block design with three replications. The following treatments were evaluated: subsurface drip irrigation without trifluralin injection (T1), subsurface drip irrigation with trifluralin injection at a rate of 4 L ha−1 (T2), subsurface drip irrigation with trifluralin injection at a rate of 6 L ha−1 (T3), subsurface drip irrigation using Nandrin pipes (T4), and traditional fixed sprinkler irrigation (S). Results demonstrated that the different treatments had a significant impact on yield and water productivity at a 1% level. Specifically, the T2 treatment, while complying with the USEPA, outperformed the other treatments with an average yield and water productivity of 20,333 kg ha−1 and 2.40 kg m−3, respectively. The average volume of applied water in the subsurface drip irrigation and sprinkler systems was measured at 8,472 and 11,480 m3 ha−1, respectively. The average 3-year yield of alfalfa in two drip and sprinkler irrigation systems was 19,779 and 14,751 kg ha−1, respectively, and the water productivity was determined as 2.4 and 1.28 kg m−3. Therefore, it can be said that the subsurface drip irrigation system, in addition to increasing crop yield by 34.1%, has caused a decrease of 26.2% in applied water, and improved water productivity by 84.6%. The study of soil salinity changes indicated an increase in field soil salinity at the end of the irrigation season in two irrigation systems, which decreased with the rainfall throughout the year.