ISHS Acta Horticulturae 792: V International Symposium on Irrigation of Horticultural Crops
ACQUISITION OF SOIL MOISTURE DATA BY A LOW COST OPTO-ELECTRONIC SOIL MOISTURE SENSOR |
| Authors: | V.P.A. Weerasinghe, H. Sinn, S. Kleisinger |
| Keywords: | irrigation, moisture characteristics, moisture conductive material, Near Infra Red, water retention curve |
| Abstract:
Supply of additional food requirements of the rapidly increasing world population (65% by 2050) put enormous pressure on world’s limited freshwater resources, since 75% of the freshwater is used for agriculture purposes. Thus, improving efficiency in irrigation is essential to address global water scarcity. Even though highly sophisticated opto-electronic sensors are available, their use in practice is often limited because of high costs. Therefore, a low cost near infra red (NIR) sensor with an inexpensive standard diode was developed for irrigation control on farm lands. In order to avoid the influence of soil heterogeneity and to increase the relevant soil volume, a moisture conductive medium was used to envelope the optical window. Increased inertia was accepted on purpose of higher accuracy. This paper deals with the moisture characteristics of this particular moisture conductive material and the accuracy of the developed opto-electronic sensor. The laboratory measured water retention curve of the moisture conductive material could be satisfactorily described with Durner threemodal retention function. The very high hydraulic conductivity at saturation (22.76 cm min-1) is in accordance with the high porosity. However, the impact of these unusual physical properties on water transfer between the moisture conductive material and the surrounding soil is not known yet but will be investigated in detail with water balance modelling. According to the calibration tests which were conducted with sensors with 900 nm diode in the laboratory the individual characteristics of the sensors were established and showed considerable of repeatability and accuracy. | |
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