Efeitos de elementos meteorológicos na evapotranspiração estimada pelo irrigâmetro na região sul do Estado do Tocantins

• Ano de defesa: 2010
• Autor(a) principal: Baptestini, Júlio Cezar Machado
• Orientador(a): Oliveira, Rubens Alves de
• Banca de defesa: Reis, Edvaldo Fialho dos , Zolnier, Sérgio , Martinez, Mauro Aparecido
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Engenharia Agrícola
• Departamento: Construções rurais e ambiência; Energia na agricultura; Mecanização agrícola; Processamento de produ
• País: BR
• Palavras-chave em Português: Irrigação; Manejo; Irrigâmetro
• Palavras-chave em Inglês: Irrigation; Management; Irrigameter
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ENGENHARIA AGRICOLA
• Link de acesso: http://locus.ufv.br/handle/123456789/3560

Irrigation is a technique that can help farmers obtain greater productivity and products of greater quality when it is done correctly. In Brazil, irrigation consumes around 69% of water used in all human activity. When the amount of water applied is insufficient to attend crop demands, productivity may decrease leaving the farmer with economics losses. On the other hand, when the application of the water is excessive, it causes increases the energy consumption, facilitates the development of diseases, reduces the quality of products, and can cause lixiviation of nutrients and contamination of water sources. Therefore, is very important that irrigation be performed properly, and the Irrigameter is one of the existent technologies for this purpose. The objectives of this project were: (a) to assess performance of the Irrigameter to estimate reference evapotranspiration (ETo) for the south region of the state of Tocantins, Brazil; (b) to assess the effects of maximal and minimal temperature, relative humidity, wind velocity and radiation on evapotranspiration as estimated by the Irrigameter (ETI); and (c) to determine the Irrigameter coefficient (KI) for each season of the year. The research was carried out in an experimental area at the Federal University of Tocantins, Gurupi Campus. Meteorological data were collected at an automatic meteorological station and used for determination of the ETo using the computer program REF-ET, based on the Penman-Monteith Equation FAO 56. The experiment was carried out in a completely randomized design and the statistical parameters used to analyze the influence of the meteorological elements on ETI were: the root mean square error (REQM), the Willmott rate (d) and the coefficient of determination (r²). The program GENES was used to analyze the correlations of direct and indirect effects of meteorological elements on the ETI. The Irrigameter showed good performance for estimating the reference evapotranspiration (ETo), and the recommended water levels in the evaporator for spring, summer, autumn and winter were 3.2, 4.2, 4.8 and 3.1 cm, respectively. The Irrigameter coefficient increased linearly with the elevation of the water level inside the evaporator for all seasons, and its values for spring, summer, autumn and winter were 0.95, 0.98, 0.96 and 1.01, respectively. During the spring, the meteorological elements of maximal temperature, relative humidity and radiation were highly correlated with the ETI. In the summer and autumn, correlation of ETI was greater with solar radiation. Relative humidity was the element presenting the highest correlation with ETI during the winter. The minimal temperature and the wind velocity showed poorer correlation with ETI for all the seasons.