Teodorico Alves Sobrinho

Perdas de solo e de água e infiltração de água em latossolo vermelho sob sistemas de manejo

Os sistemas de manejo do solo alteram o microrrelevo e a cobertura por residuos vegetais, influenciando a perda de solo e de agua. Assim, os objetivos deste estudo foram avaliar as perdas de solo e de agua e estimar a taxa de infiltracao estavel de agua no solo (TIE) em diferentes sistemas de manejo, sob chuva simulada. As avaliacoes de campo foram conduzidas sobre residuos vegetais, apos a colheita da cultura da soja (Glycine max L. Merril). Estudaram-se tres sistemas de manejo do solo: semeadura direta, preparo com grade aradora e com escarificador associados a tres niveis de cobertura do solo com residuo vegetal: 0,0; 2,0; e 4,0 Mg ha-1. Para caracterizar a area experimental foram feitas analises de densidade do solo, macroporosidade, estabilidade de agregados, umidade inicial do solo, percentual de cobertura e rugosidade superficial do solo. Por meio do uso do simulador de chuvas portatil, as parcelas receberam aplicacao de precipitacoes de 60 mm h-1. Os tratamentos foram dispostos segundo o delineamento inteiramente casualizado, arranjados em esquema fatorial 3 x 3, com tres repeticoes. As perdas de solo variaram de 1,40 a 116,30 x 10-3 Mg ha-1 h-1, enquanto as de agua, de 1,60 a 106,94 m3 ha-1 h-1. Os valores da TIE apresentaram variacao entre 23 e 52 mm h-1. Os tratamentos sob semeadura direta sem cobertura do solo e sob preparo com grade aradora apresentaram maiores perdas de solo e de agua e valores mais baixos de TIE.

Movimento de nitrato proveniente de água residuária em colunas de solos

The present work was accomplished seeking the evaluation of the movement of the nitrate (N-NO-3) originated from freezer residual waters in soil columns. For the experiment two soil types were used, one of loamy texture and another of sandy texture, respectively areas from Medianeira and Umuarama, Parana - Brazil. Four columns of PVC, of 500 mm of length and 75 mm of diameter, were mounted and filled out with the soils, with and without limestone (80% CaCO2). In the columns, after saturation with CaCl2 0,01 M, was maintained in the superior part, through flask of Mariotte, a sheet of 100 mm of residual water which allowed a displaced fluid in a total of 2.5 times the total volume of pores (Vp). It was collected for each column a total of 100 samples of the percolated effluent and it was analyzed 20 samples in an interval of each 5 samples. It was analyzed pH values, electric conductivity (CE) and concentrations of nitrate. The results of this study showed an elevation in the rate of nitrate over the initial concentration CO, for all the percolated effluent in the soils, being these values more accentuated for the column of sandy soil with limestone. The limestone addition induced a predisposition lixiviation of the nitrate and also a smaller decrease in the pH of the leached. The sandy soil, independently of the limestone, presented a larger lixiviation of total salts and of nitrate.

Variabilidade espacial do potencial erosivo das chuvas no estado de Mato Grosso do Sul

Information about rainfall erosivity is important during soil and water conservation planning. Thus, the spatial variability of rainfall erosivity of the state Mato Grosso do Sul was analyzed using ordinary kriging interpolation. For this, three pluviograph stations were used to obtain the regression equations between the erosivity index and the rainfall coefficient EI30. The equations obtained were applied to 109 pluviometric stations, resulting in EI30 values. These values were analyzed from geostatistical technique, which can be divided into: descriptive statistics, adjust to semivariogram, cross-validation process and implementation of ordinary kriging to generate the erosivity map.Highest erosivity values were found in central and northeast regions of the State, while the lowest values were observed in the southern region. In addition, high annual precipitation values not necessarily produce higher erosivity values.

Caracterização morfométrica de bacias hidrográficas através de dados SRTM

Visa-se, neste trabalho, avaliar os dados Shuttle Radar Topography Mission (SRTM) na caracterizacao morfometrica de bacias hidrograficas, atraves da comparacao das caracteristicas obtidas a partir de dados SRTM e de cartas topograficas, processados em Sistema de Informacao Geografica (SIG). O estudo foi realizado tomando-se por base a bacia hidrografica do Ribeirao Salobra, com area aproximada de 540 km2. A diferenca percentual obtida nos dados morfometricos entre os metodos estudados foi inferior a 11%, exceto no indice de circularidade (22%) e declividade media (55%). A utilizacao de dados SRTM em ambiente SIG permite a caracterizacao morfometrica de bacias hidrograficas, podendo auxiliar a gestao e o gerenciamento dos recursos hidricos, mostrando-se uma alternativa pratica e viavel ao minimizar custos e tempo na execucao dos trabalhos.

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.

Estimativa da evapotranspiração de referência através de redes neurais artificiais

The estimation of evapotranspiration by indirect methods provides synthetic data for planning irrigation systems and application on meteorological and hydrological models, both useful in watershed management. The objective of this study was to develop an Artificial Neural Network (ANN) to estimate the reference evapotranspiration (Eto) based on daily air temperature data. The ANN model of Feedforward Multilayer Perceptron type, was trained using as a reference the daily Eto obtained by the Penman-Monteith method. In the intermediate and output layers were used activation functions like tan-sigmoid and linear, respectively. Eto values generated by ANN were compared with those obtained by the methods of Blanney-Criddle and Hargreaves considering the months of the four seasons. Comparing to the other analyzed methods, the results obtained from the ANN were closer to the standard Penman-Monteith method. Thus, the performance of the developed ANN was satisfactory, and the ANN model can be considered as one indirect method for estimating evapotranspiration and allows a cost reduction on data acquisition to estimate this variable.

Infiltração de água no solo em áreas cultivadas com cana-de-açúcar sob diferentes sistemas de colheita e modelos de ajustes de equações de infiltração

As tecnicas de colheita da cultura de cana nem sempre seguem preceitos conservacionistas, fato que pode influenciar atributos fisicos do solo com consequente alteracao da velocidade de infiltracao de agua no solo. O trabalho realizado teve como objetivo avaliar o efeito de diferentes sistemas de colheita (manual e mecanizada) da cana-de-acucar (crua e queimada), sobre as caracteristicas de infiltracao e verificar a adequacao de modelos matematicos para a estimativa da taxa de infiltracao de agua no solo. Foi utilizado um simulador de chuva portatil calibrado para aplicar uma precipitacao de 60 mm h-1. Os testes de infiltracao de agua no solo foram realizados em tres sistemas de colheita: colheita manual de cana queimada, colheita mecanizada de cana crua e colheita mecanizada de cana queimada. A qualidade do ajuste dos modelos foi avaliada por meio de regressoes nao lineares entre os valores estimados e os valores medios observados em cada tratamento estudado. Nos tratamentos onde foi empregada a colheita mecânica, observou-se uma reducao da taxa de infiltracao final em relacao a area sob colheita manual de cana queimada. A equacao de Horton foi a mais adequada para a estimativa da taxa de infiltracao de agua no solo estudado.

Parâmetros físicos do solo e erosão hídrica sob chuva simulada, em área de integração agricultura-pecuária

This work was carried out in Dourados, Mato Grosso do Sul State, Brazil, in order to evaluate soil erosion and water loss in pasture and in no tillage agriculture in a pasture-agriculture integration system using a portable rainfall simulator. Four rainfall intensities (40, 60, 80 and 100 mm h-1) were studied, each consisting of a treatment arranged in an experimental design in randomized blocks with four replications. Accumulated average soil loss varied from 1.33 to 10.50 g m-2 and water loss varied from 1.34 x 10-3 to 34.64 x 10-3 m3 m-2. The largest soil and water losses occured in the largest rainfall intensities and the no-tillage system had the largest soil loss and the pasture the largest water loss.

Rugosidade da superfície do solo sob diferentes sistemas de manejo e influenciada por chuva artificial

Soil roughness is influenced by soil management, particularly by soil tillage and mainly reduced by rainfall action. This study aimed to evaluate the influence of different systems of soil management and artificial rainfall application on soil surface roughness. The treatments were a result of the combination of three systems: no-tillage, conventional tillage and minimum tillage, with three levels of dry soybean (Glycine max L. Merrill): residue: 0; 2; and 4 Mg ha-1. Experimental units received artificial rain (seven rains), at an intensity of 60 mm h-1 and during 60 min each, amounting to 420 mm rain. Roughness was evaluated immediately before and after tilling and immediately after the rainfalls. Roughness values between 1.88 and 5.41 mm were found under no-tillage, 3.88 and 8.30 mm under conventional tillage, and 3.31 and 17.45 mm under minimum tillage. It was concluded that soil tillage operations generally increased surface roughness. Values of random roughness were highest under minimum tillage; rain did not deteriorate the soil microrelief in the no-tillage treatments with soil cover.

Demanda hídrica do milho de cultivo de inverno no Estado do Rio de Janeiro

This study was conducted in order to estimate the supplemental corn water demand, in Rio de Janeiro State, Brazil, using corrected crop coefficients (Kc) for different phases of corn development. Using data from 34 meteorological stations, the irrigation demand was simulated for the corn crop for the winter season through computational program. The corrected Kc values for corn varied from 0.57 to 0.71 in the development stage I, from 0.9 to 1.12 in the stage III and from 0.63 to 0.86 in the stage IV in Rio de Janeiro State. Using these corrected Kc values in detriment of standard values, an average difference in the irrigation demand of 71.5 mm in this region was obtained.