Evaluation of Drip and Subsurface Drip Irrigation in a Uniform Loamy Soil

Abstract

Drip irrigation DI is considered one of the most efficient irrigation methods. Subsurface DI (SDI) is also a localized irrigation method, but laterals are deployed underneath the soil surface, leading to a higher potential efficiency. Among other factors, water distribution in SDI is affected by soil hydraulic properties, initial water content, emitter’s discharge, and irrigation frequency. However, complexity arising from soil water and profile characteristics means that these are often not properly considered in the design and management of these systems. In this article, irrigation uniformity in DI and SDI laterals was determined by field evaluations in a loamy soil at different inlet head pressures. Water application uniformity was very good for both irrigation methods, and differences between them were negligible. Thus, both methods may be suitable for this soil within the pressure range evaluated. The wetting pattern dimensions after infiltration for both methods were simulated with Hydrus-2D under field conditions. Wetting bulb size for DI was smaller than SDI; thus, it requires higher irrigation times to wet the same root zone. For the loamy soil, an emitter depth greater than 10 cm is advisable to prevent soil surface wetting for irrigation times higher than 30 min. Differences observed for 0.2- and 0.3-m depths were negligible. Simulations for different scenarios are depicted in graphs that might aid at the selection of proper design variables (emitter depth) and/or operation variables (inlet head and irrigation time) in the studied soil. Similar graphs could also be developed for other soils.