Evaluation of Soil Moisture Distribution and Lateral Placement Optimization of Subsurface Drip Irrigation in Sandy Clay Loam Soil

Abstract

Subsurface drip irrigation represents a compelling technological alternative to conventional surface drip systems. The water-use efficiency of subsurface drip irrigation is high compared with that of surface drip irrigation. It provides water directly to the crop root zone through buried pipelines, creating a stable wetting zone in the root zone. The optimum installation depth and spacing of laterals are two important factors in subsurface drip irrigation that should be taken into consideration to provide the maximum amount of water to the crop. Evaluation of soil moisture status in the root zone is crucial, as this depends on soil physical properties, irrigation, and water losses from the soil. This study evaluated soil moisture distribution and optimised lateral placement under subsurface drip irrigation in sandy clay loam soil. Testing emitter depths of 10, 15, and 20 cm and lateral spacings of 95, 100, and 105 cm in bare and cropped soils showed that 1–24-hour post-irrigation moisture loss varied between bare soil and soil with a crop. At the emitter position (0, 10), moisture dropped by 4.31% in bare soil versus 2.5% in cropped soil; at a 30 cm distance (30, 10), the reductions were 6.1% and 4.3%, respectively. The maximum water-use efficiency of 37.96 kg/ha-mm was recorded with a lateral spacing of 95 cm at an installation depth of 15 cm. The study also identified the optimum combination for crop yield, plant characteristics, and soil moisture distribution as a lateral spacing of 95 cm at an installation depth of 15 cm. The study suggests installing emitters at a depth of 15 cm to achieve the most balanced and efficient soil moisture footprint in sandy clay loam soil.