Paulo Afonso Ferreira

Estimativa do risco de sodificação de solos de Pernambuco pelo uso de águas salinas

An experiment was carried out in permeameters provided with vertical column and constant hydraulic head in order to evaluate sodification risks of soils with contrasting characteristics and treated with solutions of different electrical conductivities (EC) and sodium adsorption ratios (SAR). The treatments consisted of nine soils and eighteen percolating solutions with three EC values (175, 500 and 1,500 μS cm -1 ) and six SAR values (0 to 30 for sandy soils, 0 to 25 for medium textured soils and 0 to 15 for clay textured soils). Initially, the adjustment of the Na:Ca ratio on the cation exchange complex of the soils was performed using solutions with concentration of 50 mmol c L -1 . Later on leaching with solutions of different EC but same SAR was maintained to reach steady state flow, when the permeameters were dismantled and the soil samples removed for chemical analysis. Exchangeable sodium and cation exchange capacity were determined to calculate exchangeable sodium ratio (ESR) and exchangeable sodium percentage (ESP). Equations were adjusted between either ESR or ESP with EC and SAR of the percolating solution, the increment of EC and SAR elevated the soil ESR and the ESP. It may be concluded that the correct assessment of the sodification hazard has to take into consideration the soil properties and the water quality.

Utilização de água residuária de origem doméstica na agricultura: estudo das alterações químicas do solo

Neste trabalho, teve-se como objetivo principal investigar as alteracoes quimicas do solo, em resposta a aplicacao de agua residuaria filtrada de origem domestica e comparar os resultados com aqueles obtidos com o manejo convencional. O experimento foi implantado na Unidade Piloto de Tratamento de Agua Residuaria e Agricultura Irrigada, localizada na Universidade Federal de Vicosa - UFV. O delineamento experimental constituiu-se de 18 unidades experimentais, cada uma composta de oito plantas. O experimento foi montado segundo o esquema de parcelas subdivididas, tendo nas parcelas os tipos de manejo adotados (convencional - MC e com agua residuaria de origem domestica - MR, com aplicacao de cinco diferentes lâminas) e, nas subparcelas as faixas de profundidade do solo (0 - 0,20; 0,20 - 0,40 e 0,40 - 0,60 m) no delineamento em blocos casualizados (linhas de plantio) com tres repeticoes. Os resultados obtidos permitiram concluir que a adocao do MR foi mais efetiva na melhoria das caracteristicas do solo que o MC.

Condutividade hidráulica de solos de Pernambuco em resposta à condutividade elétrica e RAS da água de irrigação

An experiment was carried out in permeameters provided on vertical soil columns with constant hydraulic head in order to evaluate the hydraulic conductivity of soils with contrasting characteristics, and treated with solutions of different electrical conductivities (EC) and sodium adsorption ratios (SAR). The treatments consisted of nine soils, three EC values (175, 500 and 1.500 mS cm-1) and six SAR values of the irrigation water (0 to 30 for sandy soils, 0 to 25 for medium textured soils, and 0 to 15 for clay textured soils). Initially, an adjustment of the Na:Ca ratio in the cation exchange complex was performed with solutions at concentration of 50 mmolc L-1. The saturated hydraulic conductivity of soil (K0) was measured and the relative hydraulic conductivity (K0R) was determined, considering the maximum average K0 values of each soil as 100%. The K0R values were related to CE and SAR of the treatments, by adjusting the response surfaces. The correlation between K0 and the exchangeable sodium percentage (ESP) showed an inverse relationship between both variables in most of the studied soils. The increment in SAR resulted in the decrease of the K0R. It was not possible to define just one ESP value in order to establish a limit for sodic soils. ESP should be considered together with the EC of the irrigation water, as well as soil properties such as texture and mineralogy.

Utilização de água residuária de origem doméstica na agricultura: estudo do estado nutricional do cafeeiro

The objective of this work was to investigate nutritional status of coffee in response to application of filtered domestic wastewater and to compare the results with conventional agricultural management. The experiment was carried out at the Sewer Treatment Pilot Plant (EPTE), DEA/UFV. The experimental design consisted of 18 plots, each with eight plants. The treatments were distributed in randomized blocks design (planting lines) with three repetitions. According to the results, it may be concluded that the adoption of the management with wasterwater was more effective to improve nutritional status of coffee in comparison to conventional management.

Physical and chemical changes in an Luvisoil by the application of cattle farm wastewater

When the wastewater disposal in the soil-plant system is well planned, it can provide some benefits, such as a source of nutrients and water for plants and the reduced use of both fertilizers and their pollution potential. The soil has high capacity to decompose or inactivate the material that are potentially harmful to the environment, through chemical reactions and microbiological processes. This study was conducted to evaluate the effects of the application of cattle farm wastewater (ARB) both on physical and chemical properties of an eutrophic Red Luvisoil. The experiment was carried out using four ARB application rates (25, 50, 75 and 100 kg ha-1 K) and drainage lysimeters under greenhouse conditions. The following variables were evaluated: electrical conductivity of the soil solution; water-dispersed clay; sodium saturation index; pH; CEC; base saturation; and the contents of P, K, Ca, Mg and Na. According to the results, the increase in ARB application rates provided increments in the pH, CEC, base saturation as well as in the content of P, K, Ca and Mg in the surface layers. In the soil profile, salinization did not occur, although the percentage of clay dispersed in water increased, indicating that the steady-state ARB application may provide risks for reduction of the permeability of the soil.

Deslocamento miscível de cátions básicos provenientes da água residuária de mandioca em colunas de solo

This study aimed to determine the retardation factors and the diffusion-dispersion coefficients of the potassium, sodium, calcium and magnesium ions found in the cassava wastewater, as well as to simulate the resident concentrations in soil columns with 160 cm over a five-hours period. The trials were accomplished under laboratory conditions, by using percolation columns fulfilled with materials from the spodic ortic Quartzarenic Neosol (RQo), typical distrophic Yellow Latosol (LAd) and typical distrophic Yellow Red Latosol (LVAd). The data of the ion concentrations in effluent were analyzed, by using the miscible fluid displacement methodology. The highest values of the retardation factors occurred in the LVAd soil, relative to LAd and RQo soils, pointing out a higher retention of the potassium, sodium, calcium and magnesium ions in the LVAd soil. The values of the diffusive-dispersive coefficients decreased from LVAd toward the RQo soil, whereas the highest value occurred in the RQo soil for the potassium ion and the lowest in the LVAd soil for calcium ion. The simulation of the cassava wastewater application over a five-hours period showed little advance of these ions in the LVAd soil column, comparative to the advance occurred in the RQo and LAd soils, therefore warning about the dangers of the underground water contamination, when applying the cassava wastewater on these two soils.

Desenvolvimento de um infiltrômetro de aspersão portátil

A portable sprinkler infiltrometer with precipitation characteristics of drop diameter and kinetic energy of impact, similar to that of natural rainfall, was developed. Testing showed that the developed infiltrometer allowed continuous water application in an area of 0.70 m2 and the uniformity of water distribution, expressed by the Christiansen uniformity coefficient was between 82 and 87%. The ratio between the kinetic energy of rainfall simulated by the infiltrometer and the kinetic energy of natural rainfall was more than 90% for precipitation intensities of up to 100 mm h-1.

Equações e programa computacional para cálculo do transporte de solutos do solo

This study aimed to develop and to test a computer program for calculating the parameters of soil solute transport equations, based on adjustment of theoretical models to observed data, as well as to perform simulations for the space and temporary variations of the concentration and balance of the solute mass in the soil profile. The least-squares method (Levenberg-Marquardt) was used to obtain the estimators of the diffusion-dispersion coefficient and retardation factor parameters. The developed program, so-called DISP, is provided with a graphic interface that makes possible its use in procedures for data input, accomplishment of calculations and access to results. In the result forms, a number of graphs and tables relative to the effluent curves can be generated besides the possibility to accomplish simulations concerning to space and time variations of both concentration and balance of the solute mass in the soil profile. Comparative tests between DISP and the program CXTFIT, relative to the calculations of the Peclet number and retardation factor parameters, pointed out equivalence between both programs, however the graphic interface in DISP makes its use more feasible in relation to CXTFIT.

Produção e parâmetros fisiológicos do amendoim em função do estresse salino

EnglishThe present study aims to evaluate the effect of water salinity from irrigation on the electrical conductivity of the saturated extract of soil (CEes) and the alterations of the physiological parameters and productivity on peanut cultivation. The experiment was conducted in a randomized block design with six treatments and four replications. The treatments consisted of a control with low electrical conductivity water (0.1dS m-1) and five leaching fractions (0.4; 0.3; 0.2; 0.1; and 0.05) with water of 3 dS m-1. The results showed that the CEes decreased significantly with the increase of the leaching fractions; the decrease of the leaf osmotic potential in the peanut plant implied the reduction of productivity; the content chlorophyll and the total dry matter decreased significantly with the increase of the CEes portuguesO trabalho teve por objetivo avaliar os efeitos da salinidade da agua de irrigacao sobre o a condutividade eletrica do extrato da pasta saturada do solo (CEes) e as alteracoes dos parâmetros fisiologicos e de produtividade da cultura do amendoim. O experimento foi instalado no delineamento em blocos casualizados, com seis tratamentos e quatro repeticoes. Os tratamentos consistiram de seis fracoes de lixiviacao, equivalentes a 40, 30, 20, 10, 5 e 0% da lâmina de agua de irrigacao, sendo que para a fracao de lixiviacao de 0% usou-se agua doce (0,1 dS m-1) e para as demais agua salina (3 dS m-1). Os resultados mostraram que aCEes diminuiu significativamente com o aumento das fracoes de lixiviacao, o decrescimo do potencial osmotico foliar na planta de amendoim implicou na reducao da produtividade e o teor de clorofila e a massa de materia seca total reduziram significativamente com o aumento da CEes

Distribuição espacial da freqüência de chuvas na região hidrográfica do Atlântico, Leste de Minas Gerais

A study of spacial analysis was carried out with the rainfalls frequencies for the areas of the Atlântico hydrographic region in the eastern part in the State of Minas Gerais. The physiographic variables, such as natural vegetation, topography and wind direction, as well as the total annual rainfall using the geoestatistic Kriging technique to interpret the geospatial distribution of the rainfall frequency groups that represented the areas with homogeneous characteristics. In general, the geostatistic interpolator provided a good estimate of the total annual average rainfall for the studied area, except for the areas where the rainfall station density was relatively low. The physiographic variables and the continuous surface areas of total annual average rainfall was nearly correlated to the space distribution of the rainfall frequencies groups that represented the hydroclimatically homogeneous areas. The topography and the predominant winds at low levels showed to be the cause of the micro scale mechanisms of rainfall spatial distribution.