ABSTRACT A study was undertaken comparing the water requirements of two common bean ( Phaseolus vulgaris L.) cultivars to generate specific recommendations aimed at optimizing water use. To accomplish this work, the agronomic performance, responsiveness to water and water productivity of these two common bean cultivars of determinate and indeterminate growth habits were identified. The 2-year experiment was carried out during the winter growing season in the southeast of Brazil. Cultivars IAC Imperador, with an early season of determinate growth habit, and IPR Campos Gerais, having a mid-season of indeterminate growth habit, were subjected to five irrigation levels (54, 70, 77, 100, and 132 % of the crop evapotranspiration). Water deficit affected agronomic performance, reducing plant height (by up to 29 %), leaf area index (by up to 40 %), soil cover fraction (by up to 28 %), and grain yield (GY - by up to 31 %), in both cultivars. In contrast, excess water was more detrimental to cultivar IAC Imperador. Cultivar IPR Campos Gerais produced 18 % more than GY, showing superior water productivity and response to irrigation depth than IAC Imperador. Out of all the variables evaluated, the soil cover fraction correlated the most with grain yield in both common bean cultivars during the 2-year study. In other words, cover fraction evaluation in common bean allows for estimating crop production potential, which helps producers and technicians in their decision making regarding management practices. Thus, a cultivar directly affects water use in common bean production, thereby suggesting the need for a or water conservation strategy and sustainability of irrigated common bean production.

ABSTRACT A long-term experiment (2013 to 2017) of treated sewage effluent (TSE) levels via fertigation in a humid tropical region was installed in Jaboticabal, state of São Paulo, Southeast of Brazil, to evaluate the impact of TSE on soil fertility and the potential for salinization and heavy metal contamination of an Oxisol. The area was cultivated with Urochloa brizantha under the application of four TSE levels at the irrigation depth (0, 11, 60, and 100% TSE) during the four years of the experiment. The TSE chemical composition was monitored throughout the experimental period. The heavy metal levels and soil fertility were evaluated in the 0-0.10 and 0.10-0.20 m layers at the end of the four years of the experiment. Fertigation using TSE did not increase the concentration of potentially toxic elements (As, Cd, Cu, Hg, Mo, Ni, Pb, Se, and Zn) in the soil due to their low concentration in the effluent. A higher Na concentration was also observed at high TSE levels (60 and 100%). However, the sodium adsorption rate in the TSE was low, generating no potential for soil salinization and sodification. Fertigation with TSE levels increased soil fertility, increasing by more than 10% the P content and base saturation in the soil compared to control. According to the chemical attributes evaluated in the soil and effluent, this long-term study showed that TSE application via fertigation in humid tropical regions on clayey soils cultivated with forage grasses is recommended.

Abstract Water deficit is considered the most critical environmental factor for peanut production in Brazil, as it constitutes one of the major constraints to the expansion of its cultivation in the suitable crop zones of the country. Determining crop water demand is fundamental to increasing yield with lower water consumption. The present study aimed to evaluate the effects of full and deficit irrigation levels (L1 = 8%, L2 = 27%, L3 = 63%, L4 = 94% and L5 = 100% replenishment of crop evapotranspiration) on the development, growth and yield of peanut crop sown in two times, February and March. Treatments were distributed in a split-plot randomized complete block design, with four replicates, using a line-source sprinkler system. Irrigation depths from 65 to 314 mm were applied with the levels L1 to L5 during the first and second cropping cycles. Full irrigation with sowing in March was more advantageous due to yield increase of up to 30% compared to sowing in February, but crop cycle was 25 days longer. Water stress caused by deficit irrigation reduced plant height, seed mass and pod yield, while full irrigation (L5) led to yields from 4,141 to 5,102 kg ha-1 for February and March, approximately three times higher than those obtained with the lowest irrigation level (L1).

Resumen El déficit de agua se considera el factor ambiental más crítico para la producción de maní en Brasil, ya que constituye una de las principales limitaciones para su expansión en las zonas adecuadas para su cultivo en el país. Determinar la demanda de agua de los cultivos es fundamental para aumentar el rendimiento con un menor consumo de agua. El presente estudio tuvo como objetivo evaluar los efectos de los niveles de riego deficitarios y completos (L1 = 8%, L2 = 27%, L3 = 63%, L4 = 94% y L5 = 100% de reposición de la evapo transpiración del cultivo) en el desarrollo, crecimiento y rendimiento de la cosecha de maní sembrado en dos veces, febrero y marzo. Los tratamientos se distribuyeron en un diseño de bloques completos aleatorios de parcelas divididas, con cuatro repeticiones y utilizando un sistema de aspersores de fuente de línea. Las láminas de riego aplicadas fueron entre 65 a 314 mm (L1 a L5) en ambos ciclos de cultivo. El nivel de riego total con siembra en marzo fue más ventajoso debido al aumento del rendimiento de hasta un 30% en comparación con la siembra en febrero, pero el ciclo de cultivo fue 25 días más largo. El estrés hídrico causado por el riego deficitario redujo la altura de la planta, la masa de semillas y el rendimiento de vainas. El cultivo de maní con riego completo (L5) tuvo rendimientos de 4,141 a 5,102 kg ha-1 (febrero y marzo respectivamente) siendo aproximadamente tres veces más que los obtenidos con el nivel de riego deficitario más bajo (L1).

ABSTRACT The use of remote sensing in agriculture presents some practical applications in crop production forecast. In this context, studies with remote sensing are scarce for crops such as white oats, which may indicate the capacity of using this technique in the crop. The aim of this study was to evaluate the accuracy in validation of white oat biomass and grain yield estimates by spectral models previously calibrated using two vegetation indices (NDVI and IRVI) at three phenological stages. The mean values of NDVI and IRVI were correlated with the grain and biomass yield of white oats to obtain regression equations. The accuracy was verified by the determination coefficient (R2), root mean square error (RMSE) and mean bias error (MBE). The models were calibrated using data from a field experiment carried out in 2017 and validated with data from the same experiment, but conducted in 2018. The models had good generalization capacity for estimating yield of white oats, especially for biomass yield. Parametrized models in more advanced phenological stages, showed lower error of estimation. Models calibrated with the vegetation index IRVI had lower error of estimation than when calibrated with NDVI.

Resumo A síndrome de Cockayne é doença multissistêmica autossômica recessiva devido à falha no reparo do DNA. Originalmente descrita em 1936 em crianças com baixa estatura, atrofia retiniana e surdez, é caracterizada por nanismo, caquexia, fotossensibilidade, envelhecimento acelerado e déficits neurológicos. O mais típico é a fácies, descrita como similar à de um pássaro: maxila proeminente, atrofia do coxim adiposo bucal, olhos profundos, orelhas grandes e nariz fino. Tem sido descrita dificuldade no manejo da via aérea com estreitamento subglótico e risco de aspiração gástrica. Embora as características clínicas da síndrome de Cockayne sejam bem relatadas em publicações pediátricas, há apenas um relato de anestesia em paciente obstétrica na literatura. Relatamos o caso de gestante com diagnóstico de síndrome de Cockayne, submetida com sucesso a raquianestesia para parto cesariano por desproporção cefalopélvica. Diante da difícil decisão entre induzir anestesia geral em paciente com provável via aérea difícil ou anestesia neuroaxial, em meio a limitações cardiovasculares, respiratórias e neurocognitivas da paciente, conduta individualizada é sugerida para alcançar os melhores resultados para a gestante e o neonato.

Abstract Cockayne syndrome is an autosomal recessive multi-systemic disorder due to DNA repair failure. It was originally described in 1936 in children of small stature, retinal atrophy and deafness, characterized by dwarfism, cachexia, photosensitivity, premature aging and neurologic deficits. The most typical feature is described as birdlike facies: protruding maxilla, facial lipoatrophy, sunken eyes, large ears and thin nose. Difficult airway management with subglottic stenosis and risk of gastric content aspiration has been described. Although the clinical characteristics of Cockayne syndrome have been well described in pediatric publications, there is only one report in the literature on anesthesia for an obstetric patient. We report the case of a pregnant patient diagnosed with Cockayne syndrome, submitted successfully to spinal anesthesia for a cesarean section due to cephalopelvic disproportion. In view of the difficult decision between inducing general anesthesia in a patient with a likely difficult airway, or neuraxial anesthesia in a patient with cardiovascular, respiratory and neurocognitive limitations, we suggest tailored management to reach the best results for the mother and newborn.

ABSTRACT Knowledge on nitrogen absorption rate by crops can indicate important managements, especially the definition of rates of this nutrient and the best time for topdressing application. This study aimed to evaluate and compare the accumulation of biomass and nitrogen in white oat cultivated under severe, moderate and no water deficit. Treatments consisted of levels of irrigation, with four repetitions. The treatments under severe water deficit (L1), moderate deficit (L3) and no deficit (L5) received 11%, 60% and 100% of the water volume evapotranspired by the crop (ETc). For each treatment, six plants were collected in each replicate. After collection, plants were separated into leaves, culm and reproductive structures (panicle + grains). Second and third order regressions were tested to model the behavior of biomass and nitrogen accumulation in white oat leaves, culms, reproductive structures and total over time. The maximum total nitrogen accumulation in white oat plants in the treatments L1, L3 and L5 was 50 kg ha-1, 163 kg ha-1 and 246 kg ha-1, respectively. Severe water deficit drastically reduced biomass and nitrogen accumulation in white oat. Severe water deficit causes earlier peak of biomass and nitrogen accumulation, reduces nitrogen accumulation rate and shortens cycle of white oats.

RESUMO Técnicas de sensoriamento remoto têm sido consideradas uma nova tecnologia na agricultura mundial para o diagnóstico da demanda nutricional das plantas. A eficiência no manejo de fertilizantes é uma meta a ser alcançada, e ferramentas modernas baseadas em sensoriamento remoto são promissoras para monitorar as necessidades das culturas. Objetivou-se avaliar o desempenho agronômico e o retorno econômico relativo de aveia-branca sob doses de nitrogênio, bem como verificar se o índice de vegetação por diferença normalizada (NDVI) e o índice de clorofila foliar (ICF) podem ser utilizados para o manejo da adubação nitrogenada em cobertura, em aveia-branca. Os tratamentos consistiram de cinco estratégias de manejo de adubação nitrogenada em cobertura: T1 - 160 kg ha-1 (dose referência); T2 - 90 kg ha-1 (dose recomendada); T3 - 60 kg ha-1 (dose econômica); T4 - 30 kg ha-1 (quando NDVI < 90 % de T1); e T5 - 30 kg ha-1 (quando LCI < 90 % de T1). A aveia-branca não respondeu à adubação nitrogenada em cobertura. O seu monitoramento temporal por meio de índices espectrais permitiu dispensar a adubação nitrogenada em cobertura sem reduzir a produtividade de grãos e de biomassa e o teor de nitrogênio foliar, em relação ao manejo recomendado (90 kg ha-1 de N em cobertura), não existindo diferenças entre os índices espectrais avaliados. Assim, os índices espectrais NDVI e LCI são ferramentas promissoras para o manejo da fertilização nitrogenada em cobertura na cultura da aveia-branca.

ABSTRACT Remote sensing techniques have been considered a new technology in worldwide agriculture for diagnosing the plant nutritional demand. Fertilizer management efficiency is a goal to be achieved, and modern tools based on remote sensing are promising for monitoring the crop needs. This study aimed to evaluate the agronomic performance and relative economic return of white oat under nitrogen rates, as well as to verify whether the normalized difference vegetation index (NDVI) and leaf chlorophyll index (LCI) could be used for topdressing nitrogen fertilization management, in white oat. Treatments consisted of five topdressing nitrogen fertilization strategies: T1 - 160 kg ha-1 (reference rate); T2 - 90 kg ha-1 (recommended rate); T3 - 60 kg ha-1 (economic rate); T4 - 30 kg ha-1 (when NDVI < 90 % of T1); and T5 - 30 kg ha-1 (when LCI < 90 % of T1). The white oat did not respond to the topdressing nitrogen fertilization. Its temporal monitoring using spectral indices allowed dispensing the topdressing nitrogen fertilization without reducing the grain and biomass yields and the leaf nitrogen content, when compared to the recommended management (90 kg ha-1 of N as topdressing), with no differences between the evaluated spectral indices. Thus, both the NDVI and LCI spectral indices are promising tools for the topdressing nitrogen fertilization management in the white oat crop.

ABSTRACT One of the benefits of irrigation with wastewater in agriculture is the reduction in the use of mineral fertilizers and the increase in crop yield. For wastewater application, the use of remote sensing can help to define specific management areas. The aim of this study was to evaluate the yield and the growth of irrigated white oats (Avena sativa L.) with varying treated sewage effluent (TSE) levels. These attributes were then correlated with Normalized Difference Vegetation Index (NDVI) values obtained at four phenological stages of the crop and used to define critical limits of NDVI. The experiment consisted of five TSE treatments differing in irrigation depths (11, 31, 60, 87, and 100%). Mean NDVI values in the crop were determined with an active terrestrial sensor (GreenSeeker), which were then correlated with height, maximum leaf area index (LAI), panicles per square meter, number of grains per panicle, grain mass, grain yield (GY), and biomass yield (BY). In order to define the NDVI critical limits, NDVI values were generated as a function of relative BY in four phenological stages; NDVI values at 90% and 110% of relative BY were considered critical. Maximum GY (5.775 kg.ha-1) and BY (20,731 kg.ha-1)of white oats were achieved with TSE-induced nitrogen rates of45 kg.ha-1 and 88 kg.ha-1, respectively. NDVI readings were highly correlated (greater than 0.85) with growth and yield of white oats. In this study, we defined the critical NDVI limits of white oats and obtained maximum precision at the phenological stage 10.5.4.

RESUMO Índices de vegetação são muito utilizados para indicar o estado nutricional das culturas, bem como estimar sua produtividade final. No entanto, sua precisão é influenciada pelo estágio fenológico da avaliação e pelo índice utilizado. Objetivou-se avaliar a acurácia do Índice de Vegetação por Diferença Normalizada (IVDN) e do Índice de Vegetação de Proporção Inversa (IVPI), na predição da produtividade de grãos e biomassa de aveia-branca cultivada sob lâminas de irrigação, além de indicar o melhor estádio fenológico para avaliação. As lâminas de irrigação foram de 11 %, 31 %, 60 %, 87 % e 100 % da evapotranspiração máxima, com quatro repetições. Os valores médios de IVDN e IVPI foram determinados utilizando-se um sensor terrestre ativo, em quatro estágios fenológicos (4, 8, 10 e 10.5.4). A produtividade de grãos e biomassa de aveia branca podem ser estimadas com elevada precisão utilizando-se os índices IVDN e IVPI. O IVDN apresentou maior acurácia do que o IVPI. A estimativa da produtividade de grãos resultou em maior acurácia a partir do estádio de aparecimento da bainha da folha bandeira (10), enquanto, para a biomassa, a melhor estimativa foi para o estádio de grão aquoso (10.5.4).

ABSTRACT Vegetation indices are widely used to indicate the nutritional status of crops, as well as to estimate their harvest yield. However, their accuracy is influenced by the phenological stage of evaluation and the index used. The present study aimed to evaluate the accuracy of the Normalized Difference Vegetation Index (NDVI) and Inverse Ratio Vegetation Index (IRVI) in the prediction of grain yield and biomass of white oat cultivated under irrigation levels, besides indicating the best phenological stage for evaluation. The irrigation levels consisted of 11 %, 31 %, 60 %, 87 % and 100 % of the maximum evapotranspiration, with four replicates. The mean values for NDVI and IRVI were determined using an active terrestrial sensor, at four phenological stages (4, 8, 10 and 10.5.4). The white oat grain yield and biomass may be estimated with a high precision using the NDVI and IRVI. The NDVI was more accurate than the IRVI. The grain yield estimate was more accurate from the flag leaf sheath appearance stage (10), whereas, for the biomass, the best estimate was for the kernel watery ripe stage (10.5.4).

RESUMO. O alto consumo de água na agricultura irrigada e falta de fontes alternativas de água tornar a reutilização da água de esgoto uma opção altamente promissora nesta atividade. Este trabalho teve como objetivo avaliar o rendimento e a qualidade da forrageira Brachiaria brizantha cv. Marandu fertirrigada com águas residuais de efluente de esgoto tratado (EET) e fertilizante mineral, nos anos de 2013 e 2014, em Jaboticabal, Estado de São Paulo, Brasil. A lâmina homogênea da água foi aplicada por um sistema de irrigação por aspersão em linha tripla, mas sob aplicação gradual EET, usando os seguintes EET e água proporções: E5 = 1,0; E4 = 0,87; E3 = 0,6; E2 = 0,31, E1 = 0,11 e E0 = 0,0. O rendimento anual de biomassa aumentou com aplicação EET, variando 31,3-47,4 Mg ha-1 em 2013 e 25,7-56,9 Mg ha-1 em 2014, para E1 e E5, respectivamente. Houve sazonalidade na produção de forrageira, com os valores mais elevados no verão (35,9 a 44,7%) e primavera (35,7 a 38,4%) e as mais baixas durante a temporada de outono-inverno (19,6 a 25,7%). Apesar das altas doses de nitrogênio (1.132 kg ha-1), o rendimento máximo de forragem não foi alcançado, de modo que novos aumentos de nitrogênio ainda possam melhorar o rendimento. As baixas produtividades no outono-inverno foram compensadas pela melhor qualidade da forrageira em proteína bruta (PB) e fibra em detergente neutro (FDN).

ABSTRACT. The high consumption of water in irrigated agriculture and lack of alternative water sources make reusing sewage water a highly promising option for irrigation. This paper is aimed at evaluating Brachiaria brizantha cv. Marandu forage quality and yield when fertigated with treated sewage wastewater (TSW) and mineral fertilizer, in the 2013 and 2014 crop years in Jaboticabal, São Paulo State, Brazil. A homogeneous water depth was applied using a triple-line sprinkling irrigation system under a gradual TSW application, using the following TSW and water ratios: E5 = 1.0; E4 = 0.87; E3 = 0.6; E2 = 0.31, E1 = 0.11, and E0 = 0.0. Annual biomass yield increased with the TSW application, ranging from 31.3 to 47.4 Mg ha-1 in 2013 and from 25.7 to 56.9 Mg ha-1 in 2014, for E1 and E5, respectively. Forage yield had marked seasonality, with the highest values in summer (35.9 to 44.7%) and spring (35.7 to 38.4%) and the lowest ones during the fall-winter seasons (19.6 to 25.7%). Despite the high nitrogen rates (1,132 kg ha-1), maximum forage yield was not achieved, hence further nitrogen increments would still enhance yield. Forage improved quality has counterbalanced the low fall-winter yields in terms of crude protein (CP) and neutral detergent fibre (NDF).

RESUMO O nitrogênio (N) é o segundo nutriente mais demandado pela melancia e o que mais limita o seu crescimento e afeta a qualidade quando em deficiência. Foi avaliada a concentração de N no solo (N-nitrato), o teor de N na planta e sólidos solúveis da melancia 'Top Gun’ no Brasil, com seis doses de N (0, 50, 100, 150, 200 e 250 kg ha-1). Os valores de N-nitrato e N foliar aumentaram linearmente com as doses de N. Número de frutos total e comercial, massa de frutos total e comercial e produtividade total e comercial apresentaram efeito quadrático. A maior produtividade total e comercial foram obtidas com 187 e 184 kg ha -1 de N, respectivamente. As doses de N não influenciaram no teor de sólidos solúveis.

ABSTRACT Nitrogen (N) is the second most important nutrient required by watermelons that can limit their growth and affect fruit quality when deficient. We evaluated the soil (N-nitrate) and foliar N contents and soluble-solid content of the watermelon 'Top Gun' in Brazil at six rates of N fertilization (0, 50, 100, 150, 200 and 250 kg ha-1). N-nitrate and foliar N levels increased linearly with rate. Number of total and marketable fruit, weight of total and marketable fruit and total and marketable yields varied quadratically with rate. N rates of 187 and 184 kg ha-1 produced the highest total and marketable yields, respectively. The rate of N fertilization did not significantly affect total-solid content.

RESUMO: Objetivou-se avaliar a obstrução de gotejadores não autocompensantes utilizando efluente de esgoto tratado (EET) para irrigação. Um sistema de irrigação por gotejamento com seis modelos de gotejadores (codificados) foi instalado em nível e em condições de campo. Como água de irrigação foi utilizado EET, originado de estação de tratamento de esgoto, filtrado por um filtro de disco (120 mesh). Foram realizadas sete avaliações da vazão dos emissores (0, 100, 200, 300, 400, 500 e 600h de funcionamento), operando a 100kPa. O experimento foi montado em delineamento casualizado, com arranjo fatorial 6x7 (6 modelos e 7 tempos), com 4 repetições e teste de Tukey para comparação das médias. Foram determinados a vazão relativa (Qr), o coeficiente de variação de vazão (CVQ) e o grau de entupimento (GE). Observou-se redução na vazão em cinco modelos de gotejadores, sendo estes suscetíveis ao entupimento. O modelo com maior vazão nominal destacou-se perante os demais, apresentando Qr de 100,52%, CVQ de 2,76% e GE de 0,49%. A utilização de EET alterou a Qr dos gotejadores após 600h de funcionamento.

ABSTRACT: This study aimed to evaluate the obstruction of non-pressure compensating emitters using treated sewage effluent (TSE) for irrigation. A drip irrigation system with six models of emitters (encoded) was installed in level field conditions. TSE coming from a sewage treatment station was used as irrigation water after being filtered through a disc filter (120 mesh). Seven flow rate evaluations of drippers operating at 100kPa were performed (0, 100, 200, 300, 400, 500 and 600h of operation). The experimental design was randomized in a 6×7 factorial arrangement (6 models and 7 times), with four repetitions, and Tukey’s test was used to compare means. Relative flow rate (Qr), the flow rate coefficient of variation (CVQ) and degree of clogging (GE) were determined. There was a reduction in flow rate in five dripper models, which are susceptible to clogging. The model with rated flow stood out against the others, showing a Qr of 100.52%, CVQ of 2.76% and GE of 0.49%. The use of TSE changed the Qr of the drippers after 600h of operation.

RESUMO: Este trabalho teve como objetivo caracterizar e avaliar sete modelos de tubos emissores não regulados e de fluxo turbulento comercializados no mercado brasileiro. A caracterização dos gotejadores seguiu os procedimentos das normas NBR ISO 9261. O experimento foi conduzido na Universidade Estadual Paulista (UNESP), Campus Botucatu, Departamento de Engenharia Rural. Para a realização do ensaio foram retirados ao acaso, de cada bobina, segmentos contendo 25 emissores. Na avaliação das características hidráulicas e técnicas dos gotejadores foram determinados os seguintes parâmetros: coeficiente de variação de fabricação; coeficientes da equação característica do gotejador; espessura da parede do tubo gotejador; diâmetro interno do tubo; espaçamento entre emissores; resistência à pressão com água na temperatura ambiente e a temperatura de 40 oC; resistência do tubo a tração com tensão de 160 N e 180 N; e ensaio de envelhecimento precoce. As análises dos tubos gotejadores mostraram um coeficiente de variação de fabricação inferior a 0,056 para todos os gotejadores (0,07 é limite máximo segundo a norma). Os expoentes m da equação pressão versus vazão variaram de 0,431 a 0,575, classificando-os como não autocompensantes. Em relação a espessura da parede, o diâmetro interno dos tubos e o espaçamento entre os emissores foram constatados que todos os valores medidos estão dentro do exigido pela norma. Pelos resultados obtidos é possível afirmar que todos os produtos ensaiados ofertados no mercado brasileiro apresentaram excelente desempenho e qualidade.

ABSTRACT: This study aims to characterize and evaluate seven models of turbulent flow nonself-compensating drippers available in the Brazilian market. The characterization of the emitters followed the procedures of the standards NBR ISO 9261. The experiment was conducted at UNESP University Estadual Paulista, Botucatu Campus, Department of Rural Engineering. For the execution of the test one randomly took from each coil, segments containing 25 emitters. In the evaluation of hydraulic and technical characteristics of emitters were determined the following parameters: coefficient of manufacturing variation, coefficients of the characteristic equation of the emitter, thickness of the tube wall, internal diameter, spacing between emitters, water pressure resistance at ambient temperature and 40 oC, the tensile strength of the tube with a tension of 160 N and 180 N, and premature aging testing. The analysis of the drip tapes showed a coefficient of manufacturing variation of less than 0.056 for all emitters. The exponents (m) of the equation pressure versus flow rate ranged from 0.431 to 0.575, classifying them as nonself-compensating. About the wall thickness, the internal diameter of the drip tapes and the spacing between emitters were found out that all measured values are within the required standard. From the results obtained, it can be stated that all products tested and available in the Brazilian market showed satisfactory performance and quality.

Nos lisímetros tradicionais, o sistema de pesagem geralmente inclui uma célula de carga acoplada a uma balança com alavancas de redução de massa. O alto do custo da matéria prima e mão-de-obra dessas balanças, associado à grande oferta atual de componentes eletrônicos de coleta de dados de baixo custo, viabilizam a construção de novos equipamentos constituídos de barras de pesagem com até quatro células de carga por lisímetro. Este trabalho teve como objetivos apresentar a construção e a calibração de quatro novos lisímetros constituídos de tanques duplos retangulares, de aproximadamente 1,35 m² (1 m por 1,35 m) de superfície e 1,5 m de profundidade, apoiados sobre duas barras de pesagem. Cada barra de pesagem continha duas células de carga de alta acuracidade, ligadas por cabo coaxial a uma caixa de junção e depois a um sistema de aquisição de dados. Calibrações de cada aparelho foram realizadas após a instalação dos equipamentos no campo, resultando em ajuste linear (R2> 0,9999) entre impulso elétrico (mV) e massa (kg), com mínima histerese. O erro absoluto médio da estimativa da massa (0,0245 a 0,2844 equivalente-mm) e o índice de Wilmott entre os valores observados e estimados (d = 1,0000) indicam a alta exatidão das medições do equipamento construído. Com base nos resultados obtidos, concluiu-se que os aparelhos construídos são apropriados para estimativas de evapotranspiração e demais componentes do balanço hídrico.

Generally, standard lysimeters include a lever-load cell scale, which has become expensive compared to new electronic equipment available for experimental purposes. Currently, lysimeters containing weighing bars with up to 4 load cells are economically feasible. This goal of this study was to present the construction and calibration of four weighing lysimeters built using two rectangular tanks, with a surface area of 1.35 m2 (1 m by 1.35 m) and a depth of 1.5 m, loaded on two weighing bars. Each bar had two high accuracy loading cells connected to a junction box and a datalogger by a coaxial cable. Calibration of each lysimeter was performed after field installation. The results showed a linear response (R2 > 0.9999) of electric signal (mV) to mass increase or decrease (kg) with minimum hysteresis. The mean absolute error of the mass estimate (0.0245 to 0.2844 equivalent-mm) and a Willmott index between the observed and estimated data (d = 1.0000) indicate the high precision of the new equipment. The results allow concluding that the lysimeters in this study are appropriate for estimating evapotranspiration and other components of soil water balance.

Este trabalho teve por objetivo caracterizar e avaliar o desempenho de quatro modelos de gotejadores autocompensantes, frequentemente utilizados nos sistemas de irrigação por gotejamento no Brasil. Para realização do estudo, foi tomada uma amostra de 25 gotejadores de cada modelo. Na avaliação dos respectivos tubos emissores, foram determinados os seguintes parâmetros: (a) vazão média, (b) coeficiente de variação de fabricação, (c) espessura da parede (d), equação característica do gotejador, (e) diâmetro interno do tubo, (f) espaçamento entre emissores, (g) resistência à pressão com água na temperatura ambiente e à temperatura de 40oC, e (h) resistência do tubo à tração com tensão de 160 N e 180 N. As análises mostraram coeficientes de variação de fabricação inferiores a 0,045 para todos os gotejadores (0,07 é o limite máximo, segundo a ABNT NBR ISO 9261). Os expoentes x da equação pressão versus vazão variaram de 0,0082 a 0,0691, classificando-os como autocompensantes. Pelos resultados obtidos, é possível afirmar que nos produtos ensaiados, os quais são utilizados no Brasil pelos irrigantes, apresentaram desempenho hidráulico satisfatório, de acordo com a norma.

This study aimed to characterize and evaluate the performance of four models self-compensating drippers commonly used in drip irrigation systems in Brazil. To perform the study it was taking a sample of 25 emitters of each model. Evaluating their tubes (b) coefficient of manufacturing variation (c) wall thickness, (d) characteristic equation of the dripper, (e) internal diameter of the pipe, (f) spacing between emitters, (g) resistance water pressure at ambient temperature and to 40°C and (h) the tensile strength of the pipe with tension of 160 N and 180 N. The analysis showed variation coefficient of less than 0.045 for all manufacturing drippers (0.07 is maximum according to ABNT NBR ISO 9261). The exponents x of the equation pressure versus discharge ranged from 0.0082 to 0.0691 classifying them as self-compensating. From the results obtained it is clear that the tested products which are used in Brazil and used by irrigators had a satisfactory hydraulic performance in accordance with the standard.