Adroaldo Dias Robaina

Consumo de energia e eficiência das estações de bombeamento de lavouras de arroz irrigado

The objective of this work was to evaluate the energy consumption and the efficiency of the water pumping stations to irrigate rice crop fields at Arroio Grande, Santa Maria county, RS, Brazil,. 95 water pumping stations were visited, but only 21 were avaluated considering yield. Results showed that 67% of the water pumping stations were under 75% of it is operational efficiency. The ratio CV ha-1 showed great amplitude between the different power sources. For electrical power stations the ratio was 0.93CV ha-1 and for water pumping systems moved by tractors the ratio was 6,30CV ha-1. It was noticed that all power stations operated between 200% and 4250% over what would be normally necessary to irrigate the rice cultivated area. It was also observed that, under safe conditions electric energy could be saved up to 29% by re-evaluating head losses and, 41% if included a substitution of the current equipments pumping systems, for others minimum efficiency of 75%.

Desempenho e uniformidade da distribuição de água de um pivô central

The objective of this work was to evaluate some characteristics of a center pivot irrigation system equipament, as well as to determine the water distribuition uniformity, under and over the soil surface. The Christiansen uniformity coefficient (CUC) and distribuition (CUD) were used to evaluate the system. A low pressure center pivot was tested in four different speeds: 25%, 50%, 75% and 100% of the timer sensor, and in four collectors Unes spaced. Results indicated that both coeficients presented good performance. The values of CUC and CUD were above the minimum recommended for na irrigated corn field. The uniformity coefficients in all depths of the soil were higher than the above the soil surface. Howerer, the uniformity under soil surface increased with the time in all depths.

Níveis de irrigação na cultura do Kalanchoe cultivado em ambiente protegido

The research about the leaf development is very important to evaluate the plants growth and development. The objective of this research was to verify the different level consequences about the irrigation water manner in the leaf growth and the number of the Kalanchoe leaves. The experimental search used was completely randomized, with eight treatments, they consisted in 15; 13; 11; 9; 8; 6; 4 e 2mm irrigation in ten repetitions. The plants leaf area was calculated by the area of each leaf, multiplied by the coefficient of 1.1134. The results showed that the irrigation length between 6 and 9mm showed a bigger leaf growth and more leaves in each plant; the biggest technical efficiency was found with 6.68 and 8.59mm length, to each leaf area and the leaves number in leaf/plant, respectively. In a water condition deficit the Kalanchoe reduces a lot the leaf transversal growth related to the longitudinal.

Modelo para estimativa da produtividade para a cultura da soja

This study aimed estimate and validate a simulation model for the soybean crop in the region of Santiago, RS, Brazil which will, to the agricultural sector, support in decision making. For this, it was necessary to develop experimental procedure for generating the data needed to calibrate and test the simulation model, the extraction of water from the soil, and the response in crop production. As experimental results, obtained variations in the growth and development of soybean by applying different strategies for irrigation, resulting in different productivities. The increase in irrigation provided an increment in production components. Tests of simulated data showed a variation of less than 8% when comparing the data measured in field experiments with simulated data. The production model proposed was successfully able to simulate the accumulation of total dry matter and grain production for soybeans.

Temporal and spatial variation of parameters for the random modeling of daily rainfall in the state of Rio Grande do Sul, Brazil

Rio Grande do Sul is one of the largest grain producer states in Brazil, since most of the crops grown in non-irrigated systems, thus making them extremely dependent on the climatic conditions and on the pluviometric regime. This fact has inspired several research studies in the attempt of characterizing the spatial and temporal behavior of the rainfall. The objective of this research was to study the spatial and temporal variation of alpha and beta parameters of the gamma function for the generation of daily rainfall data in the state. The pluviometric precipitation data were obtained from the National Water Agency (ANA). The modeling of the daily rainfall was divided into the events of occurrence and quantity. Estimation of alpha and beta parameters of the gamma function was accomplished on the basis of historical series followed by the adjustment of these parameters as a function of time and space, and then the comparison between estimated and observed values. According to the results, one can conclude that the proposed methodology can be applied for the generation of synthetic series of daily rainfall in the different pluviometric stations of Rio Grande do Sul.

Tubulações em sistemas de recalque

The objective of the present research was to develop a methodology to determine efficiency tube diameter in impulsion line of pump system for irrigation. This work had some differences compared with similar procedures. The utilization of a function of tubes price for weight unit and for linear meter, also a price function of pump for potential unit and utilization of the universal equation of lost head depend on tube wall with a friction regimen. A final equation to obtain an efficient diameter allowed to stablish relationship among different elements to resolve the problem in a simple way, being necessary an interactive process, but faster as possible to reach a solution for a problem.

Modelo para determinção da área foliar de Kalanchoe blossfeldiana Poelln

This research was aimed at versifying a mathematical procedure that allows the description of leaf of Kalanchoe (Kalanchoe blossfeldiana Poelln.) and the estimation of its photosynthetically active leaf area starting from a non destructive leaf determination. Seedlings of Kalanchoe cv Gold Jewel were cultivated in irrigated vases with recommended doses for the culture. Three vases were removed weekly from the greenhouse and the plants had their leaves cut, identified and submitted to measures in plant position, longitudinal and transverse length. A total of nine data collection was carried out weekly since 04/04/2003 until blossom. Three plants were sampled weekly and leaf area were calculated using Gauss method (GARCIA & PIEDADE, 1944) implemented in Visual Basic specifically for this purpose. A total of 979 leaves were sampled and the verification of the possibility of using a medium correction factor (FCM) for leaf area independently of its position and growth cycle in the plant, was found out through regression analysis among the values obtained by the standard method (Gauss) and the estimated values for FCM method. The experimental results indicate that the value FCM=1.1134 can be used to estimate leaf area by multiplying length and width leaf values in any phase of the plant and any position of the leaf in the plant.

Determinação altimétrica através do sistema de posicionamento global

This study aims at the influence on the data acquisition with GPS receivers in altimetric determination. The altimetric survey is carried out through the method of static relative thread, using two GPS receivers of one frequency, at different times of occupation (30, 15, 10, 5 minutes), with a recording level of two seconds. The altitudes obtained with receivers GPS are compared with the altitudes determined by trigonometrical leveling with Total Station. The results showed that the periods of occupation lower than 30 minutes (15, 10 and 5 minutes) are also appropriated to obtain the centimetric differences for the analyzed altitudes. Considering the accuracy of the conventional topographical methods, this study demonstrates the possibility of the precise use of the Global Positioning System (GPS) in altimetric surveys, if modeling of the geoidal undulation is also used.

DESENVOLVIMENTO VEGETATIVO DO FEIJOEIRO IRRIGADO COM DIFERENTES LÂMINAS

Dentre os fatores que mais influenciam no sucesso de lavouras produtivas e de qualidade, o deficit hidrico esta entre um dos mais agravantes. Desta forma, a irrigacao apresenta-se como uma forte aliada, por meio da reposicao de agua requerida pelas cultiras. Neste contexto, o objetivo deste estudo foi avaliar a influencia da aplicacao de diferentes lâminas de irrigacao sobre os componentes de crescimento da cultura do feijao, cultivado na regiao de Alegrete, RS, Brasil. O trabalho foi desenvolvido em casa de vegetacao da Universidade Federal do Pampa, Campus Alegrete, RS, no periodo de fevereiro a maio de 2016. Foi utilizada a cultivar BRS Valente. Os tratamentos de irrigacao foram: 25, 50, 75, 100 e 125% de reposicao da evapotranspiracao da cultura, sob um delineamento experimental inteiramente casualizado, com quatro repeticoes. O manejo de irrigacao baseado em turno de rega fixo de quatro dias. Durante o ciclo da cultura do feijao foram avaliados os componentes de crescimento como altura de plantas (cm), diâmetro do caule (mm) e indice de area foliar (m 2 m -2 ). Para as condicoes de clima, solo e estrategia de manejo em que o experimento foi conduzido, os componentes do crescimento apresentaram-se de forma crescente conforme o incremento das lâminas de irrigacao, apresentando os maiores valores para a lâmina de 125% de reposicao da evapotranspiracao da cultura para todos os parâmetros estudados.

DESEMPENHO E PRECISÃO DE EQUAÇÕES EXPLÍCITAS DO COEFICIENTE DE PERDA DE CARGA EM REGIME DE FLUXO TURBULENTO

A equacao de Colebrook-White e amplamente utilizada para dimensionamento do coeficiente de perda de carga ( f ) de Darcy-Weisbach, sendo estipulada como padrao. Por ser uma formulacao implicita, com solucoes iterativas, diversas equacoes explicitas foram desenvolvidas para calcular o “ f ”. O objetivo desse estudo foi avaliar o desempenho dessas aproximacoes, atraves do indice de desempenho (Id) e a precisao, atraves da media do erro relativo (MER), das equacoes explicitas em relacao a implicita padrao, variando-se o intervalo do numero de Reynolds de 4x10³ ≤ Re ≤ 10 8 e da rugosidade relativa de 10 -6 ≤ Ɛ/D ≤ 5x10 -2 . As equacoes de Chen (3), Sonnad e Goudar (8), Buzzelli (9), Vantankhah e Kouchakzadeh (10), Fang et al. (11) e Offor e Alabi (13) apresentaram elevado Id, classificando-as como “Excelente” e elevada precisao quando comparadas com a aproximacao de Colebrook-White, com MER de 0,35%, 0,52%, 0,34%, 0,36%, 0,43% e 0,3%, respectivamente. Ha, portanto, relacao entre o desempenho e a precisao das equacoes analisadas, ou seja, quanto maior o Id menor sera o valor da MER.