Time filter

Source Type

Thomaz E.L.,State University of the Central West
Soil and Tillage Research | Year: 2017

The slash-and-burn agricultural system is one of the oldest types of no-tillage soil management. However, farmers using fire may cause unintentional damage to soil structure in the slash-and-burn system. Herein, it is assumed that larger soil aggregates (≥2.0 mm to <8.0 mm) are the most affected by fire, with direct impacts to their structural stability. An experimental fire was carried out, and the rainfall simulation approach for a period of 30 min with a rainfall intensity of 58 mm h−1 was used to assess the effects of fire on soil aggregate stability. The macro-aggregate stability was evaluated for the test plot as well as an undisturbed soil sample using two aggregate sizes: 2–4 mm and 4–8 mm. The fire temperature measured at the soil surface was very high (673 ± 93 °C). Consequently, the soil structural stability under the slash-and-burn agricultural system rose significantly. Larger aggregates of ≥2.0 mm or ≥4.0 mm size indicated a clear influence of fire on soil physical properties. The fire temperature dramatically changed the distribution of the aggregates of ≥4 mm, since aggregates of this size were more frequent (51%) and stronger compared to unburned soil. The methodology is critical to detect the changes in the physical properties of aggregates affected by fire. Aggregate stability methods using a single sieve of ≥0.25 mm over rainfall simulation, but without consideration of the completely fragmented particles remaining in the sieve, were not able to detect the aggregation changes. © 2016 Elsevier B.V.


De Souza V.S.,State University of the Central West
Historia, Ciencias, Saude - Manguinhos | Year: 2016

In this article, I analyze the dialogue and exchanges between Brazilian eugenicists and their counterparts abroad in the early decades of the twentieth century. Through an examination of Renato Kehl’s and Edgard Roquette- Pinto’s eugenics projects and the controversies between these two leaders of the eugenics movement in Brazil, I investigate their contact with the movements in countries like the United States, Germany, England, Sweden, and Norway and show that the ties that the two researchers maintained with socalled mainline eugenic thought were broader and more extensive than first believed. The result was the shaping of different brands of Brazilian eugenics, expanding the international circulation of ideas and extrapolating the borders of “Latin eugenics.”. © 2016, Fundacao Oswaldo Cruz. All rights reserved.


Appoloni C.R.,State University Londrina | Melquiades F.L.,State University of the Central West
Applied Radiation and Isotopes | Year: 2014

Several modern techniques have been applied to prevent counterfeiting of money bills. The objective of this study was to demonstrate the potential of Portable X-ray Fluorescence (PXRF) technique and the multivariate analysis method of Principal Component Analysis (PCA) for classification of bills in order to use it in forensic science. Bills of Dollar, Euro and Real (Brazilian currency) were measured directly at different colored regions, without any previous preparation. Spectra interpretation allowed the identification of Ca, Ti, Fe, Cu, Sr, Y, Zr and Pb. PCA analysis separated the bills in three groups and subgroups among Brazilian currency. In conclusion, the samples were classified according to its origin identifying the elements responsible for differentiation and basic pigment composition. PXRF allied to multivariate discriminate methods is a promising technique for rapid and no destructive identification of false bills in forensic science. © 2013 Elsevier Ltd.


Thomaz E.L.,State University of the Central West | Ramos-Scharron C.E.,University of Texas at Austin
Earth Surface Processes and Landforms | Year: 2015

Although unpaved roads are well-recognized as important sources of Hortonian overland flow and sediment in forested areas, their role in agriculturally-active rural settings still lacks adequate documentation. In this study, we assessed the effect of micro-catchment size, slope, and ground cover on runoff and sediment generation from graveled roadbeds servicing a rural area in southern Brazil. Fifteen replications based on 30-min-long simulated rainfall experiments were performed at constant rainfall intensities of 22-58 mm h-1 on roadbeds with varying characteristics including ~3-7 m2 micro-catchment areas, 2-11° slopes, 2-9.7-m-long shallow rill features, and 30-100% gravel cover. The contributions of micro-catchment size and rill length were the most important physical characteristics affecting runoff response and sediment production; both the size of the micro-catchment and the length of the rills were inversely related to sediment loss and this contradicts most of the rill erosion literature. The effect of micro-catchment size on runoff and sediment response suggests a potentially problematic spatial-scale subjectivity of experimental plot results. The inverse relationship between rill length and sediment generation is interpreted here as related to the predominance of coarse fragments within rills, the inability of the shallow flows generated during the simulations to erode this sediment, and their role as zones of net sediment storage. © 2015 John Wiley & Sons, Ltd.


Thomaz E.L.,State University of the Central West | Fachin P.A.,State University of the Central West
Geoderma | Year: 2014

Fire has been recognized as an important environmental process that affects soil systems. Here, we have reported the effects of temperature on soil aggregate properties of aggregate stability, mean weight diameter, water repellency, water retention, and soil carbon depletion due to soil heating. The study was performed under laboratory conditions by using a muffle furnace. However, realistic temperature gradients from 25 to 650°C were obtained previously through measurements in the field. The soil tested here is a subtropical Humic Cambisol with 500gkg-1 clay content. Most of our results were different from those reported in the literature. Following the temperature gradient, we found a sharp threshold at ~550°C. The threshold indicated two different mechanisms that affect soil aggregate properties. The first mechanism, which affects the physical characteristics of the aggregates, was associated with organic matter and water repellency reduction (≤550°C). The second mechanism was due to the thermal fusion of particles and recrystallization of mineral clays at 650°C. The reduction in soil organic carbon had a linear effect on aggregate stability, mean weight diameter, and water retention following a temperature gradient. We noted that the longer exposure time at moderate to high temperatures could not compensate for the effect of a very high peak temperature lasting for a short time on soil aggregates. For the tested soil, we found a mixed response pattern explaining the effect of soil heating on aggregate stability. © 2014 Elsevier B.V.


do Nascimento E.A.,State University of the Central West
Check List | Year: 2013

Lycids are often very aposematic toxic beetles, and are considered models in mimicry systems. They are cosmopolitan, with the highest diversity around tropical regions, however the knowledge of the South American lycids is yet relatively poor. Here I present an overview of the Brazilian lycids including a complete list of species and updated occurrence data. © 2013 Check List and Authors.


Thomaz E.L.,State University of the Central West
Agriculture, Ecosystems and Environment | Year: 2013

Shifting cultivation is an age-old agricultural system that coexists with modern agricultural systems, particularly in the tropics. The characteristics and effects of shifting cultivation are well documented in the literature, including: soil degradation and erosion, nutrient depletion, impacts on biodiversity, and economic trends. Although studies report soil loss during the cropping period under shifting cultivation, few studies have assessed soil erosion during a full slash-and-burn cycle. The objectives of this study were to characterize runoff and soil loss for a full 5-year regeneration cycle in a slash-and-burn system. The measurement of runoff and soil loss was based on three replicate 2-m2 plots installed in each monitored area. Three agricultural plots in different stages of regeneration were monitored. The data were analyzed by month and year for the 5-year regeneration cycle. Runoff and soil loss decreased exponentially from the burned phase to the early stage of secondary forest. Runoff and soil loss exhibited patterns similar to those of a forested area after only 4-5 years of regeneration. In general, areas undergoing slash and burn in the Guarapuava region are stable and the fallow length, as well. © 2013 Elsevier B.V.


Thomaz E.L.,State University of the Central West | Luiz J.C.,State University of the Central West
Land Degradation and Development | Year: 2012

Erosion and soil degradation are environmental impacts recognized worldwide. The degraded areas in the Guarapuava region are small (patchy). However, these areas are important sources of sediment that affects water quality in rural catchments and could threaten farm sustainability because farmers in this region generally have only a small area for cultivation. This paper presents a case study at a field scale that explores key questions concerning the evaluation of soil erosion, the appraisal of soil degradation and area recovery. This study was carried out over seven years (2002-2008). Several different measurement procedures were employed including assessment of soil loss, aggregation distribution, bulk density, total porosity, aggregate water retention and palisade efficiency. The degraded area displayed a very high soil loss (165.2-217.7tha -1y -1). The palisades were efficient for sediment retention because they were able to trap 62-88 per cent of the total sediment that originated in the area during the first year when this management technique was applied. After their installation, the retained sediment was gradually enhanced with respect to its physical, chemical and biological characteristics. The palisades promoted efficient soil recuperation in spite of the degraded conditions of the degraded area (shallow rills and cohesive soil). The use of palisades together with enclosure of the area was the most efficient method for promoting soil recovery and plant succession. These techniques allowed transformation of the area from a loss system towards an accumulation system with respect to sediment, water, nutrients, organic matter and seeds. © 2010 John Wiley & Sons, Ltd.


Da-Silva P.R.,State University of the Central West
Genetics and molecular research : GMR | Year: 2012

Leaf rust is one of the most destructive diseases affecting wheat worldwide. The most effective way to control it is to use resistant cultivars. Resistance based on slow-rusting adult plant resistance (APR) genes has proven to be the best method for developing cultivars with durable resistance. A source of slow-rusting APR for leaf rust is the Brazilian wheat cultivar Toropi. The Toropi/IAC 13 F2 and F7 recombinant inbred lines (RILs) were developed in previous studies. Phenotypic analysis of the F2 and F7 RILs showed that 2 recessive genes that were temporarily named trp-1 and trp-2 conferred APR in Toropi. In the present study, we used monosomic families and amplified fragment length polymorphism (AFLP), sequence-tagged site, and simple sequence repeat (SSR) markers to map trp-1 and trp-2 on wheat chromosomes. Analysis of the F2 monosomic RIL showed that trp- 1 and trp-2 were located on chromosomes 1A and 4D, respectively. AFLP analysis of the F7 RIL identified 2 independent AFLP markers, XPacgMcac3 and XPacgMcac6, which were associated with Toropi APR. These markers explained 71.5% of the variation in the phenotypic data in a multiple linear regression model. The AFLP markers XPacg/ Mcac3 and XPacg/Mcac6 were anchored by SSR markers previously mapped on the short arms of chromosomes 1A (1AS) and 4D (4DS), respectively. The trp-2 gene is the first leaf rust resistance gene mapped on wheat chromosome 4DS. The mapping of trp-1 and trp-2 provides novel and valuable information that could be used in future studies involving the fine mapping of these genes, as well as in the identification of molecular markers that are closely related to these genes for marker-assisted selection of this important trait in wheat.


Thomaz E.L.,State University of the Central West | Vestena L.R.,State University of the Central West
Earth Surface Processes and Landforms | Year: 2012

Studies of soil erosion on small plots present upscaling problems. The results in the literature on the effect of slope length (i.e. scale) on runoff and soil erosion are contradictory. Furthermore, most studies that examine scale effects measured through erosion plots have been conducted in Mediterranean environments. The objective of this study was to assess the effects of plot size on runoff and soil loss in a subtropical environment. Other measurements were taken to appraise the topsoil property changes inside the plots. The soil was ploughed twice, the surface was leveled with a hoe and it was kept bare during the experiment. Data were collected from 10 paired plots, five plots measuring 10m×1m and five plots measuring 1m×1m, installed in the same pedo-geomorphologic unit. Measurements were carried out from November 2008 to November 2009. During this period, 97 natural storms were registered. The results indicate that the small plots tended to have higher runoff (30% higher) compared to larger plots, especially during periods of greater rainfall volume, duration and intensity. The soil loss was similar in both the 1m 2 plots (6·33kg/m 2) and the 10m 2 plots (6·26kg/m 2). Moreover, the dynamics of the soil loss during the experiment was relatively similar across both plot sizes. The large plots tended to have a greater internal complexity. In these plots, the steps retreat were higher, the overland flow scars were more frequent, and points of rill initiation and protochannels emerged in several parts of the plots. The results of the small plots were comparable to the results obtained on the large plots, especially in relation to soil loss. These plots were useful for short-term assessments of soil erosion. © 2011 John Wiley & Sons, Ltd.

Loading State University of the Central West collaborators
Loading State University of the Central West collaborators