Desenvolvimento e avaliação de uma ferramenta para manejo de irrigação

Abstract

In order to quantify the water required for irrigation in a precise and efficient manner the soilplant-atmosphere system must be understood as a dynamic and integrated system of water transport mechanisms. Typically, to quantify the crop water consumption, either for irrigation projects and/or irrigation management, it is performed based on estimated reference evapotranspiration (ET0). Although, there are many methodologies available, with different conceptions to obtain the ET0, the choose of any method must to consider practicality, cost and effectiveness. The standard model for estimating ET0 is that of Penman-Monteith - FAO, which requires data that is often not available to most irrigators. So, in conditions such as these, it is necessary to develop simpler approaches to obtain ET0. In this sense, the study was carried out with the objective of determining reference evapotranspiration by a direct method, easy to construct, to use and with low cost. Aiming to do this, a simplified lysimeter was developed and its performance was evaluated in the field, taking the method of PenmanMonteith (PM) as reference. The methodology developed is a simplified evapotranspirometer, called SIL. The research was carried out in the experimental area of the Instituto Federal de Educação, Ciência e Tecnologia Baiano, Guanambi Campus. The performance of the simplified lysimeter was evaluated with mean ET0 for periods of one, three, five and seven days, referring to 90 days of observations, obtained from an automatic meteorological station and by the Simplified Lysimeter (SIL). The data were submitted to linear regression analysis and the performance was made based on standard error of estimation (SEE) and concordance "d" and performance "c" indexes. According to the results obtained, the SIL had a very good performance and overestimated the ET0 obtained by PM at 0.30 mm d-1, on average, showing good operating conditions and allowing to obtain evapotranspiration measurements in agreement with the PM method.