Desempenho do Irrigâmetro na estimativa da evapotranspiração de referência na região do Alto Paranaíba-MG

• Ano de defesa: 2009
• Autor(a) principal: Oliveira, Ednaldo Miranda de
• Orientador(a): Oliveira, Rubens Alves de
• Banca de defesa: Tagliaferre, Cristiano , Hamakawa, Paulo José , Alencar, Carlos Augusto Brasileiro de
• 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: Agricultura irrigada; Manejo de irrigação; Climatologia agrícola
• Palavras-chave em Inglês: Irrigated agriculture; Irrigation management; Agricultural climatology
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ENGENHARIA AGRICOLA::ENGENHARIA DE AGUA E SOLO::IRRIGACAO E DRENAGEM
• Link de acesso: http://locus.ufv.br/handle/123456789/3661

Quantifying the water consumption by crops and the correct scheduling for its application are valuable issues to the irrigation management. It was developed at the Federal University of Viçosa an evapo-pluviometric equipment named Irrigâmetro, which allows measuring the evapotranspiration and the precipitation, providing the right time to irrigate, the running time for the irrigation system or its speed as well. The objectives of this research were: (a) to determine the coefficient of Irrigameter (KI) to the 1, 2, 3, 4, 5 and 6 cm water depths in the evaporator, for 1, 3, 5 and 7 days intervals; (b) evaluate the performance of the Irrigameter estimating the reference evapotranspiration in the climate of the Alto Paranaíba-MG, in August 2008 to May of 2009, and (c) evaluate the interactions of the meteorological elements maximum temperature, minimum temperature, relative humidity, wind speed and radiation on the reference evapotranspiration estimated by the Irrigameter, operating with different depths of water in the evaporator. The study was conducted at the experimental station of the Federal University of Viçosa, located in the campus of Rio Paranaíba in the municipality of Rio Paranaíba, MG. The experiment was carried out in a completely randomized design with six treatments and three replications. The treatments consisted of Irrigameters equipped with evaporator operating with the following water depths: N1 = 1, N2 = 2, N3 = 3, N4 = 4, N5= 5 and N6 = 6 cm, taken from the own equipment reference level, totaling 18 Irrigâmetros. The KI coefficient was obtained by the ratio between estimated crop evapotranspiration obtained by the Irrigameter and reference evapotranspiration obtained by the Penman-Monteith - FAO 56 method. The analysis of the performance of the Irrigameter to estimate the reference evapotranspiration was made comparing the results with those obtained from the device to the equation Penman-Monteith - FAO 56. The ranking of the evapotranspiration estimative was based on the values of the standard estimative error (SEE), coefficient of determination (r2) and the equation parameters (a and b) of the linear regressions. The best alternative was the one that had higher r2, lower SEE and b near to the unit. The accuracy was amended by the WILLMOT agreement index, represented by the letter "d", where the values range from zero for no agreement to 1 for perfect agreement. To evaluate the direct and indirect effects of each climatic component on the evapotranspiration estimated by the Irrigameter, the path analysis was used, where evapotranspiration was the dependent variable and the climatic elements were the independent variables. The coefficient of Irrigameter increased with the increase of water level within the evaporator, for all time intervals. The water depth in evaporator to estimate the evapotranspiration of reference were: 4.1, 4.0, 3.6, 3.8, 3.3, 3.0, 2.5, 3.3, 3, 0 and 2.9 cm for the months of August, September, October, November, December, January, February, March, April and May, respectively. For the path analysis, the climatic factors that had high correlation with the estimate of the evapotranspiration of Irrigameter were the relative humidity for the months of August and January, minimum temperature and relative humidity for the month of September, maximum temperature and relative humidity, for the month of October and minimum temperature for the month of May. The lowest correlation with the main variable was presented by the variable wind speed, and not significant at 1 and 5% probability by the test t.