Development and evaluation of an irrigation system with ultra low flow using microtubes branched

Author(s)

Dinara Grasiela Alves

• Document type: Master's Dissertation
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2011-01-21

Examining board members

Tarlei Arriel Botrel; Ceres Duarte Guedes Cabral de Almeida; Sergio Nascimento Duarte

• Advisor: Tarlei Arriel Botrel

Abstract

To develop a sustainable agriculture in Brazil is essential to invest in sectors that produce innovative technologies, adapted to Brazilian peculiar conditions and with a low cost, that can replace the dependency on imported products, often not accessible to small producers. In this way, the emitters microtube utilizes in microirrigation can be attractive technological alternative for this kind of farmers, due to the low cost and installation. However, to achieve high uniformity of water application is essential that microirrigation system have to be well designed. This work has to aim to develop an irrigation system with ultra low flow (ULF) of 0.2 L h-1, using microtubes with derivation and operating in laminar flow, this work began searching for efficient irrigation and lowcost vegetable crops. The configuration of the proposed system consists of a lateral line with a nominal diameter of 10 mm in which the microtubes connectors with a nominal diameter of 0.8 mm were inserted directly and through a segment of pipe closed at both ends, six microtubes emitters with a nominal diameter of 0.7 mm were connected to the connectors. The experiment was performed in two steps. The first part of experiment was conducted in the Hydraulics Laboratory, Department of Biosystems Engineering, School of Agriculture \"Luiz de Queiroz\" (ESALQ / USP) in Piracicaba SP. It was determined the actual diameter of the microtubes and obtained the mathematical models for irrigation system design and to evaluate the observed discharge. The second part of the experiment was performed in an experimental vegetable garden located in the area of ESALQ / USP. It was realized the assembly and installation of irrigation system, the tests to obtain the uniformity of water application and plantation of lettuce crop into four beds 15 m x 1.5 m, where water was provided by an elevated water tower at a height of 1.5 m. The water application uniformity was evaluated by the statistical coefficient of uniformity and distribution uniformity which it showed initial values above 90% that it is considered excellent. The irrigation system with ultra low flow proposed showed economic advantages for small producers due to low cost and ease of system operation. However, this system presented problems of air accumulation and emitters clogging during the period evaluated, it caused a reduction in uniform distribution and uniform statistics. Therefore, it is necessary to perform further studies to obtain more conclusive results. (AU)