Desenvolvimento e avaliação hidráulica de um sistema de gotejamento por gravidade para pequenas propriedades

Abstract

Growers who have small subsistence vegetable farms in Brazil have difficulty managing irrigation and using water efficiently. A simple kit for gravity feed drip irrigation was designed for these growers to facilitate their efficient water use and simplify their irrigation management. It is made up of drip tubes labyrinth type, disk or screen filters, 12mm fittings and a polyethylene tubing 20.6mm internal diameter. For design the application uniformity adopted was at least 90%. The first part of this work was conducted at the Hydraulics Laboratory at Engineering Department at Federal University of Lavras, where the hydraulic characteristics of the emitter were evaluated. The emitters were submitted to tests for measuring the manufacturing coefficient of variation (CVf), the characteristic equation and the maximum lateral length (Lmax), accordingly international criteria. The obtained value for CVf was 2.59% on a 30 meters lateral operating under 2.5 mca of pressure, and the exponent for the characteristic equation was 0.5052. Consequently, the emitters were classified as excellent due to the uniformity and the flow regime as turbulent. The evaluation of application uniformity at field presented values larger than 85.15%. The fertigation uniformity was tested with injection of liquid fertilizers (containing Nitrogen, Phosphorus and micronutrients) and also a solid mix later diluted in water with MAP, Ureia and Potassium Nitrate). The results obtained revealed an uniformity of at least 93.96%.