Desempenho do irrigâmetro na estimativa da evapotranspiração de referência

Abstract

Neste trabalho objetivou testar o Irrigâmetro para estimar a evapotranspiração de referência comparativamente com o método de Penman-Monteith - FAO 56, e confrontar o seu desempenho com os métodos Penman modificado - FAO 24, Radiação - FAO 24, tanque Classe A e Hargreaves-Samani (1985). O Irrigâmetro é um aparelho evapo-pluviométrico desenvolvido recentemente na Universidade Federal de Viçosa para ser utilizado no manejo da irrigação. Os dados de evapotranspiração de referência (ETo) obtidos no aparelho foram confrontados com os dados obtidos pelo método de Penman-Monteith, em intervalos de um, três, cinco e sete dias. Conforme os resultados, o Irrigâmetro apresentou desempenho satisfatório para estimar a ETo em todos os intervalos de tempo estudados. Este desempenho, associado ao baixo custo, à alta praticidade e à inexistência de cálculos, torna o aparelho indicado para o manejo da água na agricultura irrigada. Os métodos de Penman modificado, Radiação e Hargreaves-Samani, superestimaram os valores da ETo obtidos pelo método de Penman-Monteith, tendo o tanque Classe A apresentado comportamento oposto.

Nitrogen fertilization strategies for xaraes and tifton 85 grasses irrigated in the dry season

“…Urea, single superphosphate and potassium chloride were used as N, P and K sources, respectively. The irrigation control was done with an irrigameter (Oliveira et al, 2008). Soil samples were obtained for the determination of wilting point, field capacity and soil density.…”

Reference evapotranspiration for Londrina, Paraná, Brazil: performance of different estimation methods

“…Figure 2 presents the distancing from the regression straight line to the straight-line y = x, showing a less accuracy of methods, with a low R 2 for the Hargreaves-Samani (1985) method and a decrease of the Willmott index (d) for the original Penman method. The lower performance of the methods Hargreaves-Samani (1985), Linacre, Benavides-Lopez, Lungeon, and Ivanov when compared to other models was also observed by several authors in other regions (OLIVEIRA et al, 2008;ALENCAR et al, 2011;CUNHA et al, 2013), which can be attributed to the fact that these methods consider only data of temperature or temperature and relative air humidity, excluding the interference of other meteorological variables in evapotranspiration. However, the method Hargreaves-Samani (1985) presented reasonable precision and accuracy indices, being possible to propose, as in Sentelhas and Camargo (1996), a local calibration to the method so that producers in the region without access to complex meteorological data can manage the irrigation only with minimum, maximum, and average temperature data.…”

Use of millimeter ruler as an alternative tool in the phenotyping of potential descriptors of soybean

“…A series of studies report the utilization of the statistics used in this work for comparing the different estimates of reference evapotranspiration (Tagliaferre et al, 2012;Oliveira et al, 2008). In soybean, these statistics were used to validate models of simulation for this crop in Santiago, RG, Brazil (Gomes et al, 2014) and to compare the estimate of leaf area of old and modern varieties by a non-destructive method (Richter et al, 2014).…”