(614) PRACTICAL SESSION FOR THE DEGREE PROGRAM OF AGRICULTURAL ENGINEERING. USING SOIL VOLUMETRIC HUMIDITY PROBES AS A TOOL TO SUPPORT IRRIGATION SCHEDULING

摘要

‘Irrigation Engineering' is a subject included in the third year of the Bachelor's Degree in Rural andAgrifood Engineering at the Universitat Politecnica de Valencia. This subject provides the knowledgenecessary for the design, project and management of the different pressure irrigation systems, amongothers drip irrigation, and make up an important part of the engineering job opportunities forgraduates.In this kind of subjects, experimental and practical training appear as an essential complement oftheoretical 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 ofFrequency Domain Reflectometry (FDR) probes for continuous measurement of the soil water contentis studied for control and irrigation scheduling.In a first part, the students visit a citrus experimental plot with drip irrigation in which an experiment onRegulated Deficit Irrigation (RDI) with three irrigation treatments is performed. RDI consists on thereduction of water supplies during certain stages of crop development, when yield and fruit qualityhave low sensitivity to water deficit, providing normal irrigation during the rest of the season, especiallyduring the 'critical periods' or phenological stages with a higher sensitivity to water deficit. Thevolumetric water content through the soil profile was monitored continuously using a multisensorcapacitance probe based on FDR. With this aim, three FDR probes were installed in the experimentalplot (one probe per treatment).The second part of the practical session takes place at the computer lab, where the students shouldassess and become aware of the suitability of such probes in the detection of applied irrigation orprecipitation amount, their behaviour when deficit irrigation is applied, the ability to detect deeppercolation losses, etc. Furthermore, students should also realize the good relationship betweenmeasures of soil moisture probes obtained with the FDR and the water status of the plant, whichenables its use in the control of conventional irrigation and regulated deficit irrigation treatments.After a preliminary part guided by the lecturer, the students will get additional moisture profiles whichshould be analysed and discussed in groups. Afterwards, each group will present its conclusions tothe rest of the students.