Evaluation of an experimental system of soil moisture registration for irrigation management in potted vineyard (Vitis vinifera L. CV Bobal) of multi-depth temperature compensation based in resistivity measurements

• A minimal cost, temperature compensated soil moisture measurement system for determining irrigation water requirements in real time.
• Local data-logging incorporated to provide resilience against communications network failures.
• Design for cost effective deployment in micro-managed irrigation environments and geographical areas where water is a critically scarce resource.
• Capable of low cost expansion to provide a range of additional data and services.
• The calibration of the device and the conditions of use in a variety of soil types are demonstrated.

Measurement of soil moisture is a fundamental parameter for irrigation scheduling. In order to determine this parameter, many types of sensors are employed. Some of these sensors for soil moisture measurements are based on electric resistivity. Measurements are affected by many factors including soil temperature, length of probes, amongst others, that can cause incorrect determination of soil moisture levels. Consequently, this can lead to inappropriate or unnecessary irrigation. The main objective of this paper is the presentation of results of several experiments focused on determining adequate temperature compensation for a simple soil moisture measurement and registration system based on resistivity measurements (Wenner compensation). Moreover, a comparison between the data obtained by this device and a reference sensor is included. The device was calibrated in a plot with potted vineyards (Vitis vinifera L. cv Bobal on 110R) under drip irrigation and additional conditions. Results are adequate and include a method of compensation of measured values based in a rolling average model of soil temperature with a good agreement. A simple weighed combination of box temperature of the device and 14 cm deeper temperatures can provide a useful level of Wenner compensation. Additionally, this device has a competitive price and is adequate for water management in crops.