A field experiment was conducted during the autumn of 2021 at the Agricultural Research Department station / Abu Ghraib to evaluate the soil moisture, water potential distribution, and growth factors of maize crops under alternating and constant partial drip irrigation methods. In the experiment, two irrigation systems were used, surface drip irrigation (DI) and subsurface irrigation (SD); under each irrigation system, five irrigation methods were: conventional irrigation (CI), and 75 and 50% of the amount of water of CI of each of the alternating partial irrigation APRI75 and APRI50 and the constant partial irrigation FPRI75 and FPRI50 respectively. The results showed that the water depth for conventional irrigation (C1) was 658.3 and 579.4 mm for the DI and SD irrigation systems, respectively, and the irrigation depth was reduced to 18% when applied APRI75 and FPRI75 and 37% when applied APRI50 and FPRI50 respectively. The moisture distribution differed according to the irrigation method, and the SD provided a higher moisture content and lower water potential due to the lower evaporation rate from the soil surface. Also, the growth traits of maize varied according to the irrigation system and its methods. The SD system was significantly superior in the grain yield of maize with an increase of 5.4% compared with DI, and the alternating partial irrigation treatments were significantly superior to the constant partial irrigation. Keywords: Matric suction, Zea mays L., irrigation system, irrigation depth.
