RESUMOO métodos padrão de estimativa da evapotranspiração de referência (ET0) FAO PenmanMonteith (PM) emprega variáveis meteorológicas as quais nem sempre estão disponíveis à maioria dos produtores rurais. Assim, o presente trabalho teve por objetivo avaliar seu desempenho e aferir se necessário, para as condições da Paraíba, diferentes métodos para a estimativa diária de ET0, comparando-os com o método padrão FAO Penman-Monteith. Utilizou-se uma série histórica de 17 anos de dados meteorológicos do INMET de quatro cidades do Estado da Paraíba. Os métodos avaliados foram os de Hargreaves-Samani (HS), Blaney-Criddle (BC), Camargo (C) e Jensen-Haise (JH). Para análise comparativa entre o método PM e os outros métodos, foi realizada a análise de correlação e regressão linear e do coeficiente de determinação (R²). Para a exatidão dos métodos empíricos, foi realizada a análise para a determinação do índice de concordância (d) e do índice de desempenho (c). A ET0, obtida pelos quatro métodos empíricos obtiveram desempenho satisfatório, o método HS para a mesorregião do agreste não necessitou de ajustes, já os métodos JH, C e HS para as mesorregiões litoral, borborema e sertão necessitaram de ajuste para melhor acurácia em relação ao método padrão. Palavras ABSTRACTThe standard method for estimating reference evapotranspiration (ET0), FAO PenmanMonteith (PM) employs meteorological variables which are not always available to most

The water depth to be applied is a factor of utmost importance for the success of irrigated crops. The objective of this study was to evaluate the correlation of ETo estimate methods proposed by Hargreaves and Samani, Camargo and Jensen-Haise (JH) and the standard PenmanMonteith-FAO (PM-FAO) method, by setting up regional adjustment coefficients for the region of Rio Parnaiba, MG. Climate data collected at the meteorological station in Rio

A B S T R A C TThis study aimed to evaluate the flow variation of pressure-compensating emitters using treated sewage effluent (TSE). A drip irrigation system with four types of pressurecompensating emitters (G1 -Naan Dan Jain Model Top Drip, G2 -Naan Dan Jain Model Naan PC, G3 -Drip-Plan, G4 -Naan Dan Jain Model Naan Amnon) was installed with TSE from the sewage treatment station, filtered through a disc filter (120 mesh). Seven evaluations of flow rate of the drippers were performed (0, 100, 200, 300, 400, 500 and 600 h of operation) operating at 100 kPa. The experimental design was completely randomized in a 4 x 7 factorial arrangement (4 models and 7 times) with four replicates and Tukey test to compare the means. The relative flow rate (Qr), flow rate coefficient of variation (CVQ) and degree of clogging (DC) were determined. It was found that the models of emitters were not much susceptible to clogging during the operation of the system. The G4 model showed better performance compared with the others, presenting mean Qr of 99.92%, CVQ of 2.69% and DC of 1.19% at the end of the experiment. The results revealed that emitters are affected by the time of use of TSE.

One of the main factors that determine the success of decision-making in the fields is the climatic factor. This way, the geostatistical techniques have been used to represent and understand the spatial or temporal dynamics of meteorological parameters. Therefore, the aim of this research was to represent temporally through thematic maps, the average daily behavior for meteorological variables and the hydric balance for the municipality of Patos de Minas-MG. The climatic data were acquired from the automatic station INMET from the years 1990 to 2015. Later, it was calculated the evapotranspiration and the hydric balance for different capacities of available water in the soil (CAW): 24 mm, 48 mm, 80 mm and 112 mm. The climate variables showed temporal dependence, and through the thematic maps, derived from the ordinary Kriging, it was possible to identify the seasons of the year that are favorable for the production for the different crop groups.

MODELOS DE CURVA DE RETENÇÃO DE ÁGUA NO SOLO  ROBERTO FILGUEIRAS¹; VINICIUS MENDES RODRIGUES DE OLIVEIRA²; FERNANDO FRANÇA DA CUNHA³; EVERARDO CHARTUNI MANTOVANI³ E EPITÁCIO JOSE DE SOUZA4 1 Doutorando em Engenharia Agrícola, Universidade Federal de Viçosa. Viçosa, MG. Email: roberto.f.filgueiras@ufv.br²    Doutorando em Engenharia Agrícola, Universidade Federal de Viçosa. Viçosa, MG³    Prof. Dr. Departamento de Engenharia Agrícola, Universidade Federal de Viçosa. Viçosa, MG4      Doutorando em Agronomia (Ciência do Solo), UNESP. Ilha Solteira, SP.  1 RESUMO  O objetivo deste trabalho foi comparar a umidade na capacidade de campo e ponto de murcha permanente obtida com os modelos de obtenção da curva de retenção de água no solo de van Genuchten e potencial e ainda comparar os valores de capacidade de campo obtidos com a tensão de 6 e 33 kPa. Para isto ajustaram-se os modelos van Genuchten e potencial para as tensões de 10, 30, 50, 100, 500 e 1500 kPa, através da câmara de Richards. Posteriormente, encontrou-se os valores de umidade para as tensões na capacidade de campo (6 e 33 kPa) e ponto de murcha permanente (1500 kPa). Ambos os modelos predisseram a umidade na capacidade de campo a 33 kPa e o ponto de murcha permanente com alta precisão, exatidão e concordância, quando comparado os dois métodos. Palavras-chave: van Genuchten, potencial, capacidade de campo.  FILGUEIRAS R.; DE OLIVEIRA V. M. R.; CUNHA F. F. DA; MANTOVANI E. C.; E. J. DE SOUZA.WATER RETENTION CURVE MODELS IN THE SOIL       2 ABSTRACT The objective of this study was to compare the moisture at field capacity and permanent wilting point obtained by the models and potential for obtaining the soil water retention curve by van Genuchten, also comparing the field capacity values with the tension of 6 and 33 kPa. Thus, it adjusted the van Genuchten model and potential for voltages of 10, 30, 50, 100, 500 and 1500 kPa through Richards chamber, subsequently finding the moisture values for the voltages at field capacity (6 and 33 kPa) and permanent wilting point (1500 kPa). Both models predicted moisture at field capacity at 33 kPa and the permanent wilting point with high precision, accuracy and harmony, when the two methods are compared. Keywords: van Genuchten , potential, field capacity.

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Water wastage is a great concern worldwide. Water is effectively utilized by using equipment and systems that have more uniform water distribution. The objective of this study was to evaluate the performance of the FR Super 10 sprinkler with a pressure compensator under different pressures, spacing, and installation heights. The tests were performed in the laboratory, and pressure was controlled with two gauges calibrated with a mercury column. The distribution uniformity was measured using the Christiansen uniformity coefficient (CUC) and distribution uniformity coefficient (CUD). Four spray nozzles were utilized for the Super 10 sprinkler, at two heights (0.6 and 1.2 m), six pressures (25, 30, 35, 40, 45, and 50 m H 2 O), and six spacings (9 × 9, 9 × 10, 10 × 10, 9 × 12, 10 × 12, and 12 × 12 m). The blue, yellow, and red nozzles presented self-compensating features and the green nozzle was not fully self-compensating. The manufacturing coefficients of variations were lower in the nozzles with smaller apertures (blue and yellow) compared to those with larger apertures. Increasing the sprinkler height provided better water distribution uniformity and a better radial distribution profile, lowering the application rate near the sprinkler. Since this sprinkler compensates for pressure changes, pressure did not influence the sprinkler range. Key words: CATCH-3D. CUC. CUD. Self-compensating. Water saving. ResumoAtualmente há grande preocupação com o desperdício de água. Utilizando equipamentos e sistemas que possuem maior uniformidade de distribuição de água, obtém-se melhor aproveitamento da água aplicada. O objetivo deste trabalho foi avaliar o desempenho do aspersor modelo FR Super 10 com compensador de pressão, sob diferentes pressões de trabalho, espaçamentos e alturas de instalação. Os testes foram realizados em laboratório, controlando-se a pressão com dois manômetros previamente calibrados com coluna de mercúrio e a uniformidade de distribuição avaliada utilizando-se o Coeficiente de Uniformidade de Christiansen (CUC) e o Coeficiente de Uniformidade de Distribuição (CUD). Foram utilizados quatro bocais do aspersor Super 10, duas alturas (0,6 e 1,2 m), seis pressões (25, 30, 35, 40, 45 e 50 m.c.a.) e seis espaçamentos (9x9, 9x10, 10x10, 9x12, 10x12 e 12x12 m). Os bocais azul, amarelo e vermelho apresentaram características autocompensantes e o bocal verde não foi totalmente autocompensante, os coeficientes de variação de fabricação (CV) foram maiores nos bocais com menor