Abstract:

‘Irrigation Engineering’ is a subject included in the third year of the Bachelor’s Degree in Rural and Agrifood Engineering at the Universitat Politècnica de València. This subject provides the knowledge necessary for the design, project and management of the different pressurized irrigation systems, among others drip irrigation, which make up an important part of the engineering job opportunities for graduates.

In this kind of subjects, experimental and practical training appear as an essential complement of theoretical fundamentals, studied and analysed in the lecture classes in depth.

This paper describes a practical session of the subject ‘Irrigation Engineering’ in which the use of Frequency Domain Reflectometry (FDR) probes for continuous measurement of the soil water content is studied for control and irrigation scheduling.

In a first part, the students visit a citrus experimental plot with drip irrigation in which an experiment on Regulated Deficit Irrigation (RDI) with three irrigation treatments is performed. RDI consists on the reduction of water supplies during certain stages of crop development, when yield and fruit quality have low sensitivity to water deficit, providing normal irrigation during the rest of the season, especially during the ‘critical periods’ or phenological stages with a higher sensitivity to water deficit. The volumetric water content through the soil profile was monitored continuously using a multisensor capacitance probe based on FDR. With this aim, three FDR probes were installed in the experimental plot (one probe per treatment).
The second part of the practical session takes place at the computer lab, where the students should assess and become aware of the suitability of such probes in the detection of applied irrigation or precipitation amount, their behaviour when deficit irrigation is applied, the ability to detect deep percolation losses, etc. Furthermore, students should also realize the good relationship between measures of soil moisture probes obtained with the FDR and the water status of the plant, which enables its use in the control of conventional irrigation and Controlled Deficit Irrigation treatments.
After a preliminary part guided by the lecturer, the students will get additional moisture profiles which should be analyzed and discussed in groups. Afterwards, each group will present its conclusions to the rest of the students.

Keywords:

Practical training, autonomous learning, irrigation scheduling.