Software for the automatic control of irrigation using weighing-drainage lysimeters

© 2014 Elsevier B.V.Among all the existing methods to study crop water requirements, necessary for an efficient irrigation management, the most accurate is the one based on the use of weighing lysimeters. The best known lysimeters are those used for crops in bare soil, with similar dimensions to the plantation frame of the measured species. These lysimeters are buried in the ground, require civil works, have a high cost and are commonly used in experimental plots to determine crop coefficients. There are cheaper and smaller scale lysimeters used to monitor water balance in pots without civil works. Although crop coefficients obtained from these lysimeters are not comparable to those obtained from crops in the ground, they may be useful to accurately determine the plants water needs so they can be used as a reference to irrigate the rest of potted plants of the plot.The objective of this work was to develop and evaluate a software system to optimize irrigation using weighing lysimeters in a potted crop. The software was programmed in a compact embedded controller using the LabVIEW graphical programming language with the Real-Time module. This controller receives data from the lysimeters throughout a Modbus/RS-485 communication network, processes them and realizes the calculations to control the irrigation valves in real time. The system was tested in an experimental plot owned by the "Escuela Politécnica Superior de Orihuela" with Vitis Vinifera L. cv Bobal. The software allowed the acquisition and data logging as well as irrigation scheduling based on water balance obtained from weighing lysimeters i.e. based exclusively on actual crop water needs.