Performance of surface and subsurface drip irrigation system

Abstract

The present study aimed to evaluate the uniformity of surface and subsurface water distribution in drip irrigation systems in sandy soil. The experiment was conducted in the area of the Faculty of Agronomy of the State University of Piaui, from November, 2020. The treatments evaluated were: T1: irrigation with drip hoses on the soil surface; T2: irrigation with subsurface hoses at a depth of 0.20 m; and T3: irrigation with subsurface hoses at a depth of 0.40 m. Each plot consisted of 4 dripper strips, 10.0 m long, using the Drip Net in-line drippers, with 0.3 m spacing between emitters, nominal flow of 2 L h-1, service pressure 15 mca. After the implantation of the irrigation system, flow and pressure tests were carried out. The duration of each irrigation was 4.0 hours daily in each area, starting at midnight (0:00 am) and ending at 4:00 am. Soil collections for moisture determination were carried out every 4 (four) days, with samples collected after 01 hour of the end of irrigation. In the evaluation of the surface drip, to quantify the flow of each emitter, plastic cups with a capacity of 200 ml were used to collect water during 01 minute. Soon after, each container was weighed on a precision scale, to then convert the weight into volume and obtain the flow (L h-1). Uniformity was assessed using the distribution uniformity coefficients (CUD), Christiansen uniformity coefficient (CUC) and statistical uniformity coefficient (CUE). The system presented a performance classified as excelent for different coefficients in all evaluated treatments.