Software application for real-time ET _o /ET _c calculation through mobile devices

Abstract

In the southeast of Spain, farmers usually resort to the Agricultural Information Service of Murcia (SIAM) to get the data needed for an estimation of their water use and needs. Through 48 automatic stations, the SIAM provides data about temperature, wind speed, solar radiation or humidity, on a not very user-friendly web page which is not adapted to mobile devices and shows some shortcomings in downloading data. In addition, the key reference parameter in irrigation, the daily reference evapotranspiration (ET _o ), is not provided on the current day and the hourly ET _o and the crop evapotranspiration (ET _c ) are not offered either. This paper presents a new software application for mobile devices capable of providing the required data by an easy-to-use and friendly app. This tool employs the GPS co-ordinates of a place under study to get the data required from the closest SIAM stations and interpolates station data to increase accuracy. The hourly and daily ET _o are automatically calculated using the Penman–Monteith equation, declared by the FAO in 1990 as the only valid method for calculating evapotranspiration. The ET _o computation entails the calculation of the net solar radiation, the heat soil flux or the psychometric constant. A new extension of the tool also allows calculation of the ET _c for a set of typical crops of the southeast of Spain. All the computed data can be stored and edited, as well as those geographical positions of interest. To the best of the authors’ knowledge, this is the first application of this kind available.