João C. F. Borges Júnior

Métodos de estimativa da evapotranspiração de referência diária para a microrregião de Garanhuns, PE

For high frequency irrigation management, based on climate data, it is desirable to estimate reference evapotranspiration at small time steps. This work aimed at to evaluate the performance of daily reference evapotranspiration estimated by the following methods: FAO-24 Radiation, Priestley-Taylor, Hargreaves-Samani, Camargo-71 and Blaney-Criddle, for Garanhuns-PE micro-region, having FAO Penman-Monteith method as standard. Considering the mean absolute error (MAE), among other statistics, it was verified that the best performance was obtained by the Priestley-Taylor method. Regarding the methods applicable when only temperature data are available, the Hargreaves-Samani showed the best performance, having been calibrated based on the minimization of the MAE.

Displacement of solutes in soil columns with domestic and swine raising wastewater

With the objective of evaluating the parameters of transport retardation factor, dispersion-diffusion coefficient and effluent curves of the ions calcium, magnesium, sodium and potassium, present in domestic and swine raising wastewater, an experiment was conducted in laboratory with columns of Red Yellow Argisol and Regolithic Fluvisol. With the aid of flasks of Mariotte around two pore volumes of distilled water were passed in the columns; soon after, another flask was interconnected containing the wastewaters which leached 3.75 volume of pores divided in 25 aliqnot, totaling 600 samples. The obtained results lead to the conclussion that the retardation factors were higher for the sodium in the Red Yellow Argisol and for the magnesium in Regolithic Fluvisol leached with treated domestic wastewater. In reference to the swine raising wastewater, the largest values were calculated for the ion magnesium, in the two soils; as for the dispersion-diffusion coefficients, the highest values were observed for Regolithic Fluvisol, independent of the type of water.

Sistemas de drenagem agrícola. Parte I: desenvolvimento do modelo e análise de sensibilidade

Este trabalho contempla o desenvolvimento de um modelo computacional, visando suprir as principais lacunas em relacao aos modelos existentes, e realizar analise de sensibilidade, objetivando verificar o efeito dos parâmetros de entrada sobre os resultados obtidos pela aplicacao do modelo. O modelo contabiliza diariamente os principais componentes do balanco hidrico em um volume de controle de base unitaria e altura igual a distância entre a superficie do solo e a camada impermeavel, situado a meia distância entre dois drenos paralelos, a mesma profundidade simulando, assim, a movimentacao do lencol freatico. O modelo utiliza funcoes de producao que consideram o estresse causado por excesso e por falta de agua na zona radicular, realiza analise economica para diversas configuracoes do sistema de drenagem determinando-se, entao, o espacamento economico entre drenos, alem de informar sobre a viabilidade economica do empreendimento. Com a analise de sensibilidade, verificou-se que os parâmetros profundidade media dos drenos, condutividade hidraulica horizontal do solo saturado, porosidade drenavel, parâmetros climaticos, coeficiente CN e custo de instalacao dos drenos subterrâneos, exercem maior influencia no calculo do espacamento economico entre drenos.

Sistemas de drenagem agrícola. Parte II: comparação entre o modelo desenvolvido e outras metodologias

This study aimed at comparing the results obtained from the developed model, PRODREN, with those obtained from the DRAINMOD model thoroughly tested in the United States, and with the SIMDRENO model, as well as with methodologies traditionally used in dimensioning the agricultural drainage systems in areas of humid and sub-humid climates. Simulations for lowering the water table were accomplished by using these three models. The results from the drainage system design for maize crop, which was obtained by using the three models as well as by application of the traditional methodologies, were compared. The results from simulations of the water table and the economic design of the drainage systems accomplished with PRODREN were similar to those obtained by DRAINMOD and SIMDRENO models. The spacing among drains obtained by application of the PRODREN, SIMDRENO and DRAINMOD models based on water balance and economic analysis were considerably larger than those resulting from the employment of traditional methodologies.

Análise de risco e otimização de recursos hídricos e retorno financeiro em nível de fazenda

Este trabalho teve como objetivo analisar padroes de cultivo em uma propriedade rural, visando a otimizacao do uso de recursos hidricos e a maximizacao do retorno financeiro, para um estudo de caso no Agreste Meridional Pernambucano. O modelo de programacao linear com horizonte de planejamento de tres anos utilizado, foi implementado na planilha Microsoft® Excel. Este modelo visou a maximizacao do valor presente liquido total do empreendimento. Para a analise de risco foram utilizadas duas tecnicas complementares: a simulacao de risco, procedida com o programa @Risk, e a analise de sensibilidade. No primeiro padrao de cultivo, PC1, com restricao hidrica mensal para irrigacao de 8.500 m3, o maximo valor presente liquido total, VPLt , foi de R

Daytime Net Radiation on Cowpea and Castor Bean in the County of Areia-PB and Garanhuns-PE

8.771,10 (ha ano)-1; no segundo padrao de cultivo, PC2, com restricao hidrica mensal de 4.000 m3, o VPLt foi de R

Transporte no solo de solutos presentes na água residuária de café conilon

8.228,77 (ha ano)-1. Na analise de risco, observou-se que os valores encontrados do VPLt foram positivos e proximos para os dois padroes de cultivo evidenciando a nao expectativa de fracasso financeiro, mas com consideravel reducao da demanda de agua para irrigacao para o PC2, indicando o potencial da metodologia aplicada a gestao de recursos hidricos na regiao.

EQUAÇÃO DE HARGREAVES-SAMANI CALIBRADA EM DIFERENTES BASES TEMPORAIS PARA SETE LAGOAS, MG

continuum, such as evapotranspiration, however, its direct measurement is not available for most weather stations in Brazil. Thus, the objective of this work was to determine the relationship between Rn and incident solar radiation (Rg) in cowpea and castor bean canopies. The Rn and Rg data were collected from experiments conducted during in the years 2002 and 2003 (cowpea), 2004 and 2005 (castor bean) in Areia, PB (6 o 58’ S, 35 o 41’ W e 620 m), and 2009 (castor bean) in Garanhuns-PE (8 o 53’ S, 36 o 29’ W e 842 m). Were performed daily sums of Rn and Rg, from 6 to 18h, and then it was calculated the Rn/Rg ratio for each day. Models with high R 2 (above 0.93), d and c indices (above 0.90) and low RMSE (below 0.83) were obtained in test between measured and estimated values, indicating precision to estimate Rn in cowpea and castor bean canopies as a function of Rg. The general linear function for castor bean and cowpea were Rn = 0.5965 Rg (R 2 = 0.943) and Rn = 0.7822 Rg (R 2 = 0.976), respectively. Net radiation can be satisfactorily estimated from incoming solar radiation for both crops.