SUMMARY:The main objective of this paper was to develop a separable linear programming model, considering a set of technical factors which may influence the profit of an irrigation project The model presents an objective function that maximizes the net income and specifies the range of water availability. It is assumed that yield functions in response to water application are available for differents crops and describe very well the water-yield relationships. The linear programming model was developed genetically, so that, the rational use of the available water resource could be included in an irrigation project Specific equations were developed and applied in the irrigation project "Senator Nilo Coelho" (SNCP), located in Petrolina -Brazil Based on the water-yield functions considered, cultivated land constraints, production costs and products prices, it was concluded that: (a) the model was suitable for the management of the SNCP, resulting in optimal cropping patterns and showing the water requirements; (b) for 7,424 ha of land and 66, 644,500 m 3 of water available on a year basis, the shadow price of these resources were respectively, US$ 1,115.20/ha e USS 281.60/1000 m 3 ; (c) for the total monthly water availability of 9,861,040 m 3 , the total annual water availability of 66,644,500 m 3 became an effective restriction to the increase of the net income of the production system in the SNCP; (d) maintaining the total monthly water availability of 9,861,040 m 3 , annual volumes lower than 88,338,983 m 3 were used fully to reach the optimal solution, and that higher volumes than this limit, did not increase the net return; (e) the optimization model presented, estimated a net return of 5234 % higher than the traditional cropping pattern used hi the SNCP, considering the agricultural year of 1992. , volumes anuais inferiores a 88338.983 m 3 foram utilizados plenamente pelas atividades na solução ótima e, volumes superiores a este apresentam folga, não contribuindo para o aumento da receita liquida (e) o modelo de otimização desenvolvido projetou uma receita líquida 52,34% maior que a obtida com o plano de cultivo tradicional do PSNC, considerado, como exemplo, o ano agrícola de 1992.
O estudo do transporte dos componentes químicos da vinhaça no perfil do solo é importante, tanto do ponto de vista ambiental quanto econômico. O uso da modelagem computacional nos permite de maneira precisa e rápida o monitoramento do deslocamento de solutos, importante na prevenção de impactos ambientais. Portanto, a obtenção e o entendimento dos parâmetros de transporte de solutos no solo auxiliam na redução da sua lixiviação para as camadas subsuperficiais. Neste sentido, objetivou-se, obter os parâmetros de transporte do sódio e potássio via vinhaça, a velocidade da água nos poros, o fator de retardamento, a dispersividade e o coeficiente de dispersão, tendo sido este trabalho feito em laboratório com colunas de solo Nitossolo Vermelho eutrófico. O ensaio foi conduzido empregando amostras deformadas coletadas na camada de 0-20 cm, posteriormente, a estas amostras foi aplicada vinhaça. Após a obtenção dos parâmetros de transporte, ajustados pelo programa computacional DISP, notou-se que as curvas de efluentes para ambos os íons estudados apresentaram semelhança em sua inclinação. Pelos resultados obtidos, os parâmetros de transporte evidenciaram positivamente os efeitos de adsorção e de deslocamento dos íons sódio e potássio presentes na vinhaça, principalmente em relação ao íon potássio.
RESUMO:Neste trabalho, buscou-se avaliar a suscetibilidade de modelos de tubos gotejadores ao entupimento, quando expostos ao uso de cloreto de potássio (branco e vermelho), aplicados via diferentes qualidades de água. O experimento foi realizado no Laboratório de Irrigação do Departamento de Engenharia Rural da Escola Superior de Agricultura "Luiz de Queiroz" -ESALQ/USP, por um período de nove meses, analisando o desempenho de oito modelos de tubos gotejadores convencionais, com quatro tratamentos e dez repetições, sendo cada repetição representada por um gotejador. Os tratamentos aplicados foram: (T1-Lg/B) água do lago x cloreto de potássio branco; (T2-Lg/V) água do lago x cloreto de potássio vermelho; (T3-Lb/B) água do laboratório x cloreto de potássio branco, e (T4-Lb/V) água do laboratório x cloreto de potássio vermelho. Os modelos de tubos gotejadores apresentaram desempenhos variáveis, sugerindo que a arquitetura interna dos gotejadores foi o fator determinante na caracterização do processo de entupimento. Não foi observado elevado entupimento com relação à aplicação dos cloretos de potássio branco e vermelho na ausência ou presença de fitoplâncton, mostrando que é possível utilizar cloreto de potássio vermelho em fertirrigação. PALAVRAS-CHAVE:fertirrigação, uniformidade de distribuição, irrigação localizada. CLOGGING OF CONVENTIONAL DRIPLINES UNDER THE APPLICATION OF POTASSIUM CHLORIDE (WHITE AND RED) WITH TWO WATER QUALITIESABSTRACT: This work aimed to evaluate the susceptibility of several dripline models against the clogging process when exposed to potassium chloride (white and red), applied through different water qualities (fertigation). The experiment was accomplished in three phases, at the Laboratory of Irrigation of the Department of Rural Engineering at ESALQ/USP, for a period of nine months, by analyzing the performance of eight conventional drip models, with four treatments and ten repetitions, being each repetition a dripper. The applied treatments were: (T1-Lg/B) water of the lake x chloride of white potassium; (T2-Lg/V) water of the lake x chloride of red potassium; (T3-Lb/B) water of the laboratory x chloride of white potassium and (T4-Lb/V) water of the laboratory x chloride of red potassium. The dripline models presented variable performance, suggesting that internal architecture of emitters is a major factor related to clogging resistance for imposed treatments. It was not observed high clogging with the application of white or red potassium chloride, under different water quality conditions, showing that it is possible to use the red potassium chloride for fertigation without problems.
Infrared thermometry is a possibility of detection of plant water stress by measuring the temperature of a portion of the canopy without requiring physical contact with the sheets. The purpose of this study was determining the crop water stress index in tomato cherry using the leaf temperature in plants as an indicator of water stress. Plants were grown in a greenhouse situated in the Department of Biosystems Engineering at the Escola Superior de Agricultura "Luiz de Queiroz "in Piracicaba, São Paulo. The plants were conducted in eight 500L boxes. The soil of the boxes is Oxisol eutrophic typical. Previously, were defined two groups: with induced water stress (T0; 24 plants) and without water stress (T1; 24 plants). The temperature of canopy was measured before irrigation using a thermal camera which captures infrared images. The leaf and air temperatures were used to calculation of crop water stress index (IEHC) in two moments: 41 and 47 days after transplanting (DAT) using the lower basal limit (LBI) and a theoretical method. The leaf temperature in group T0 was higher than observed in group T1. We found that: i) highest IEHC in both groups was less than 0.7; ii) IEHC based on theoretical method or LBI, showed that stressed plants have higher IEHC than plants with less water stress. The results indicate that water stress in tomato cherry could be estimated by IEHC based on LBI.
This work aims to quantify possible disturbances of flow rate in drip emitters subject to the application of potassium chloride, suspended solids, water containing organic material and concentrated solution of soluble iron. The experiment was accomplished in the Laboratory of Irrigation of the Department of Biosystem Engineering at ESALQ/USP, analyzing the performance of 22 drippers. All treatments had water with phytoplankton + 1 kg of clay soil, with applications of potassium chloride and positioning of emitters ranging as follows: T1: white potassium chloride with dripper facing down (T1+So+Sc↓); T2: red potassium chloride
RESUMO:O superfosfato simples (SS) é uma alternativa aos adubos fosfatados que são utilizados via fertirrigação, como o ácido fosfórico, que provoca acidificação do bulbo úmido no solo, e o monofosfato de amônio purificado, que apresenta maior preço. No entanto, não se conhece o efeito de tal adubo no funcionamento de emissores, principalmente nos gotejadores, nem se é possível controlar o entupimento por SS por meio de aplicações de ácido. Assim, desenvolveu-se este trabalho com o objetivo de avaliar a possibilidade da utilização do superfosfato simples via gotejamento, como alternativa ao uso de outros adubos fosfatados, e a tentativa de controle do entupimento utilizando ácido nítrico. O trabalho foi desenvolvido em bancada de ensaios de gotejadores, localizada no Laboratório de Hidráulica da ESALQ/USP. Foram aplicadas doses de 50; 75 e 100% da solubilidade do superfosfato simples (SS), em 26 tubogotejadores de diferentes marcas comerciais, e ao fim de 360 horas de irrigação, foi aplicado ácido nítrico com pH 2, na tentativa de desentupir os gotejadores mais sensíveis. Diante dos resultados, foi possível inferir que o uso do superfosfato simples pode ser feito via fertirrigação, e o ácido nítrico, aplicado segundo esta metodologia, não proporcionou a desobstrução dos emissores. PALAVRAS-CHAVE:adubos fosfatados, gotejamento, obstrução de emissores. DYNAMIC BLOCKAGE OF DRIPPERS AS A FUNCTION OF THE APPLICATION OF SUPER SIMPLE PHOSPHATE AND NÍTRIC ACID IN LOCALIZED IRRIGATION ABSTRACT:The super simple phosphate (SS) is an alternative to the phosphorous fertilizers which are used through fertigation, as the phosphoric acid, which triggers acidification of the wetted volume in the soil, and the monophosfato of purified ammonium, that has a higher price. However, the effect of such fertilizer in the emitters function, mainly in the drippers, is not known neither if it is possible to control the blockage for SS through acid applications. Thus, this study was developed in order to evaluate the possibility of the use of super simple phosphate trough drip irrigation, as an alternative to the use of other phosphorous fertilizers, and the attempt of controlling the blockage with nitric acid. The work was carried out in bench of drippers rehearsals, located at the Hydraulic laboratory in ESALQ-USP. Doses of 50; 75 and 100% of the super simple phosphate (SS) were applied in 26 emitter tubes with different commercial marks, and after 360 hours the nitric acid with a pH of 2 was applied, in the attempt of clearing the most sensitive drippers to the blockage. With the results it was possible to infer that: the use of super simple phosphate can be done by fertigation without causing damages to the system and the nitric acid, applied according to this methodology, did not provide the clearance of the emitters.
To quantify water stress on coffee trees, leaf water potential (LWP) measurements are commonly performed in a Scholander chamber; however, this methodology is restricted to research activities, due to the difficulty of measurement in the field: sampling hours at predawn and intensive work. A crop water stress index (CWSI) based on leaf temperature has been used as indicative of LWP in several crops, and thermal images can be a precious tool for mapping LWP under intensive drip‐irrigated coffee areas, in order to adjust irrigation requirements according to soil moisture spatial variability. This study aims to define the relationships between the water potential of coffee leaf based on CWSI, calculated by means of a portable infrared sensor and a thermal camera, analysing correlation, precision and accuracy indexes. The study was conducted in Piracicaba, SP, Brazil, using Coffea arabica species of the Catuaí Red variety IAC 144 that was drip irrigated using tensiometers as matric potential sensors. The observed CWSI and LWP presented good correlations in the linear and cubic models. It was concluded that the CWSI is a good indicator of the water potential of a coffee canopy and can be an alternative to measurements of LWP from the Scholander chamber. © 2020 John Wiley & Sons, Ltd.
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