Wanderley de Jesus Souza

Erosão hídrica em um Argissolo Vermelho-Amarelo, sob diferentes padrões de chuva simulada

This study was carried out in order to determine the soil, water and nutrient losses in a Yellow-Red Ultisol, under four different patterns of simulated rainfall. The experiment was conducted at the Embrapa Agrobiologia experimental field, located in the municipality of Seropedica, Rio de Janeiro, Brazil. The study consisted in the application of simulated rains using variable rainfall intensity classified in different patterns as: advanced (AD), intermediate (IN), delayed (DE), and constant (CT), in plots 0.8 m wide and 1.0 m long. The rain had a duration of 60 min, with a total applied depth of 30 mm, and a peak of 110 mm h-1, for the variable intensity patterns. With the results obtained it was possible to verify that after 60 min of simulated DE pattern provided losses higher than CT, AD and IN, in 61.6, 46.4 and 13.6%, respectively (soil), and 42.0, 19.0 and 19.0% (run-off), respectively, for the AD, IN and CT patterns; and the nutrients losses did not differ among the rainfall patterns, being more affected by water run-off than solid material in suspension.

Irrigação localizada subsuperfical: Gotejador convencional e novo protótipo 1

A B ST R A C T Subsurface drip irrigation that uses an emitter protection system to avoid its clogging by roots and soil particles may be viable compared to a conventional system. The objective of this work was to evaluate the performance of a system with emitter protection, and to compare the results with a system that uses a conventional emitter for subsurface drip irrigation. In the system with protection an inexpensive materials polyethylene hose, microtube, connector, and a dripper to control the flow rate were used; and, in the conventional system a commercial emitter was used. After 12 months of evaluation, the system with protector showed good performance, with relative average flow rate of 0.97 and 0.98 in pots with and without crop, respectively, showing no clogging problems and lower cost. In conventional system relative flow rate of 0.51 and 0.98 were observed in pots with and without crop, respectively, also clogging degree by roots of 49.22%, and emitters with soil inside was observed. Thus, the use of emitter with protection presented feasibility for subsurface drip irrigation, under conditions used in this research.

Fertigação em mudas de citros utilizando-se mangueiras e microtubos sob regime de escoamento turbulento

The use of localized irrigation using microtube as emitter under turbulent flow regime can be a technically feasible alternative. The objective of this study was to evaluate the performance of a fertigation system in nursery of citrus plants (greenhouse) projected by universal mathematical model, using the microtubes as emitters, under turbulent flow rate and to compare the development of the fertigated plants by microtubes to the system that use the traditional method with hoses. In the size of the length of the emitters was considered the K coefficient of localized energy dissipation using a microtube with internal diameter of 0,761 mm. The fertigation system presented great performance with clogging degree, Christiansen uniformity and emission uniformity values equal to 0,50; 99,95 and 98,21%, respectively, after 160 days of study. Plants that were grown using fertigation with both microtubes and hoses showed no difference as regards to stem diameter and height. Thus, the use of the microtube under turbulent flow rate presented technical feasible for fertigation system.

Modelo matemático aplicado à irrigação localizada com microtubos sob regime de escoamento turbulento

O presente trabalho teve como objetivos, desenvolver dois modelos matematicos para dimensionamento de microtubos em irrigacao localizada, operando sob regime de escoamento turbulento, nos quais foram incluidas as perdas de carga no microtubo, perda de carga localizada e perdas por energia de velocidade na saida do microtubo. Para a determinacao da perda de carga localizada, obteve-se, por meio de dados de laboratorio, valores de coeficientes K de dissipacao de energia na entrada do microtubo. Os modelos foram avaliados com o dimensionamento de uma linha lateral de irrigacao e tiveram otimos desempenhos, tendo em vista que os dados coletados proporcionaram vazao media proxima da vazao de projeto, com coeficiente de determinacao acima de 98%, excelente uniformidade de distribuicao, baixo erro medio absoluto e coeficiente de variacao de vazao. Dessa forma, pode-se dizer que o sistema de irrigacao com microtubos, em regime de escoamento turbulento, mostrou-se tecnicamente viavel para utilizacao, e que os modelos matematicos desenvolvidos foram adequados para a avaliacao das perdas no sistema.

Perdas de água e solo sob diferentes padrões de chuva simulada e condições de cobertura do solo

This study was carried out in order to determine the soil and water losses in a Yellow-red Ultisol, under four different rainfall patterns and two conditions of soil cover: area with soil uncovered and with straw after corn planting. The experiment was conducted at the experimental field of Embrapa Agrobiologia, located at Seropedica municipality, State of Rio de Janeiro, Brazil. The treatments consisted in application of simulated rainfall using variable intensity classified in different patterns as: advanced (AV), intermediate (IN), delayed (AT), and constant (CT), in a plots with 0.8 m of width and 1.0 m of length. Using a portable rainfall simulator rainfall with 30 mm total depth during 60 minutes was applied. For the patterns with varied intensity, the peak of precipitation was 110 mm h-1. The results showed the cover of the soil with corn stubble substantially reduced the rates and the soil and water losses, mainly for the pattern of constant rainfall, indicating that the residues left on the ground after harvest helps effectively in the erosion control.