Home Itens selecionados Provedores de dados OAI Créditos Sobre Ajuda

			Busca avançada
	Provedor de dados Braz. J. Vet. Res. Anim. Sci. (1) Autor Bombonato,Pedro Primo (1) Carneiro e Silva,Frederico Ozanam (1) Nocetti,Luciana Mantovani (1) Santana,Marcelo Ismar Silva (1) Severino,Renato Souto (1) Palavra-chave Animais selvagens (1) Coração (1) Vasos coronários (1) Tipo do documento Info:eu-repo/semantics/article (1) Ano 2002 (1) País Brazil (1) Idioma Português (1)		Ordenar por:  Relevância Autor Título Ano Registros recuperados: 73 Primeira ... 1 2 3 4 ... Última Delineation of irrigation management zones in a Quartzipsamment of the Brazilian semiarid region PAB Oldoni,Henrique; Bassoi,Luís Henrique. Abstract The objective of this work was to delineate irrigation management zones using geostatistics and multivariate analysis in different combinations of physical and hydraulic soil properties, as well as to determine the optimal number of management zones in order to avoid overlaping. A field experiment was carried out in a Quartzipsamment, for two years, in an irrigated orchard of table grape, in the Senador Nilo Coelho Irrigation Scheme, in the municipality of Petrolina, in the state of Pernanbuco, Brazil. Soil samples were collected for the determination of soil physico-hydraulic properties. A portable meter was used to measure soil apparent electrical conductivity. Spatial distribution maps were generated using ordinary kriging. Management zones for... Tipo: Info:eu-repo/semantics/article Palavras-chave: Fuzzy c-means; Geostatistics; Irrigation planning; Precision agriculture; Soil apparent electrical conductivity; Spatial variability. Ano: 2016 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-204X2016000901283 Web software to create thematic maps for precision agriculture PAB Borges,Ligia Francielle; Bazzi,Claudio Leones; Souza,Eduardo Godoy de; Magalhães,Paulo Sergio Graziano; Michelon,Gabriela Karoline. Abstract: The objective of this work was to develop and provide a free web application able to generate thematic maps. The initiative aims to incorporate the functionalities of the “Software para Definição de Unidades de Manejo” (SDUM) desktop application, which has proven to be suitable for working with thematic maps and management zones, but that was only available for desktop computers. The developed web application was tested with real data from two agricultural fields located in the state of Paraná, Brazil. Thematic maps of soil and plant characteristics relevant to precision agriculture were created through the following interpolation methods: inverse distance, moving average, and nearest neighbor. The obtained results show that the usage of this web... Tipo: Info:eu-repo/semantics/article Palavras-chave: AgDataBox-Map software; Digital agriculture; Geoprocessing; Interpolation; Spatial variability. Ano: 2020 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-204X2020000100800 VARIABLE RATE NITROGEN APPLICATION ON CORN FIELDS: THE ROLE OF SPATIAL VARIABILITY AND WEATHER AgEcon Roberts, Roland K.; Mahajanashetti, S.B.; English, Burton C.; Larson, James A.; Tyler, Donald D.. Meta-response functions for corn yields and nitrogen losses were estimated from EPIC-generated data for three soil types and three weather scenarios. These metamodels were used to evaluate variable rate (VRT) versus uniform rate (URT) nitrogen application technologies for alternative weather scenarios and policy option. Except under very dry conditions, returns per acre for VRT were higher than for URT and the economic advantage of VRT increased as realized rainfall decreased from expected average rainfall. Nitrogen losses to the environment from VRT were lower for all situation examined, except on fields with little spatial variability. Tipo: Journal Article Palavras-chave: Corn; Environment; Meta-response functions; Nitrogen restriction; Precision farming; Site-specific management; Spatial variability; Weather variability; Crop Production/Industries. Ano: 2002 URL: http://purl.umn.edu/15512 ECONOMIC AND ENVIRONMENTAL BENEFITS OF VARIABLE RATE APPLICATION OF NITROGEN TO CORN FIELDS: ROLE OF VARIABILITY AND WEATHER AgEcon English, Burton C.; Mahajanashetti, S.B.; Roberts, Roland K.. The use of meta-response functions based on EPIC-generated data resulted in comparisons between variable (VRAT) and uniform rate application technologies for 36 simulated fields. VRAT was more profitable and less nitrogen was lost to the environment in most cases. When spatial variability was small, uniform rate application techniques were adopted. However, when nitrogen use is restricted, VRAT is used on all simulated fields. Tipo: Conference Paper or Presentation Palavras-chave: Precision farming; Site-specific farming; Spatial variability; Nitrogen restriction; Rainfall; EPIC; Crop growth simulation model; Meta-response functions; Environmental Economics and Policy; Research and Development/Tech Change/Emerging Technologies; Resource /Energy Economics and Policy. Ano: 1999 URL: http://purl.umn.edu/21533 SPATIAL BREAK-EVEN VARIABILITY FOR CUSTOM HIRE VARIABLE RATE TECHNOLOGY ADOPTION AgEcon Mahajanashetti, S.B.; English, Burton C.; Roberts, Roland K.. A theoretical model identified ranges of spatial variability required within multiple-land-class fields for economically viable variable rate technology (VRT) and the spatial variability required for maximum return to VRT. An example illustrated that return to VRT and the viable range of spatial variability increased for higher corn and nitrogen prices. Tipo: Conference Paper or Presentation Palavras-chave: Precision farming; Site-specific farming; Nitrogen; Corn; Spatial variability; Yield variability; Profit function; Land Economics/Use; Resource /Energy Economics and Policy. Ano: 1999 URL: http://purl.umn.edu/21676 ASSESSING SPATIAL BREAK-EVEN VARIABILITY IN FIELDS WITH TWO OR MORE MANAGEMENT ZONES AgEcon English, Burton C.; Mahajanashetti, S.B.; Roberts, Roland K.. Farmers are interested in knowing whether applying inputs at variable rates across a field is economically viable. The answer depends on the crop, the input, their prices, the cost of variable rate technology (VRT) versus uninform rate technology (URT), and the spatial and yield response variability within each field. Methods were investigated for determining the range of spatial variability over which the return to VRT covers its additional cost compared with URT in fields with multiple management zones. Models developed in this article, or variants thereof, could be used to help farmers make the VRT adoption decision. Tipo: Journal Article Palavras-chave: Management zones; Nitrogen; Precision farming; Site-specific management; Spatial break-even variability proportions; Spatial variability; Variable rate technology; Yield response variability; Farm Management. Ano: 2001 URL: http://purl.umn.edu/15450 STOCHASTIC TECHNOLOGY, RISK PREFERENCES AND ADOPTION OF SITE-SPECIFIC TECHNOLOGIES AgEcon Isik, Murat; Khanna, Madhu. This paper develops a model of farmer decision-making to examine the extent to which uncertainties about the performance of site-specific technologies (SSTs) and about the weather impact the value of these technologies. The model uses the jointly estimated risk and technology parameters to examine the impacts of SSTs on returns and nitrogen pollution. The availability of uncertain soil information and production uncertainty can lead risk-averse farmers to apply more fertilizers and generate more pollution. Ignoring the impact of uncertainty and risk preferences of farmers leads to a significant overestimation of the economic and environmental benefits of SSTs and underestimation of the required subsidy for inducing adoption of SSTs. The model that accounts... Tipo: Conference Paper or Presentation Palavras-chave: Spatial variability; Risk preferences; Joint estimation; Uncertainty; Technology adoption; Nitrogen runoff; Research and Development/Tech Change/Emerging Technologies. Ano: 2002 URL: http://purl.umn.edu/19858 Scaling of semivariograms and the kriging estimation of field-measured properties Rev. Bras. Ciênc. Solo Vieira,S. R.; Tillotson,P. M.; Biggar,J. W.; Nielsen,D. R.. Two methods were evaluated for scaling a set of semivariograms into a unified function for kriging estimation of field-measured properties. Scaling is performed using sample variances and sills of individual semivariograms as scale factors. Theoretical developments show that kriging weights are independent of the scaling factor which appears simply as a constant multiplying both sides of the kriging equations. The scaling techniques were applied to four sets of semivariograms representing spatial scales of 30 x 30 m to 600 x 900 km. Experimental semivariograms in each set successfully coalesced into a single curve by variances and sills of individual semivariograms. To evaluate the scaling techniques, kriged estimates derived from scaled semivariogram... Tipo: Info:eu-repo/semantics/article Palavras-chave: Semivariogram; Scaling; Kriging; Spatial variability. Ano: 1997 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06831997000400001 USE OF SCALED SEMIVARIOGRAMS IN THE PLANNING SAMPLE OF SOIL PHYSICAL PROPERTIES IN SOUTHERN AMAZONAS, BRAZIL Rev. Bras. Ciênc. Solo Aquino,Renato Eleotério de; Campos,Milton César Costa; Marques Junior,José; Oliveira,Ivanildo Amorim de; Teixeira,Daniel De Bortoli; Cunha,José Maurício da. There is a great lack of information from soil surveys in the southern part of the State of Amazonas, Brazil. The use of tools such as geostatistics may improve environmental planning, use and management. In this study, we aimed to use scaled semivariograms in sample design of soil physical properties of some environments in Amazonas. We selected five areas located in the south of the state of Amazonas, Brazil, with varied soil uses, such as forest, archaeological dark earth (ADE), pasture, sugarcane cropping, and agroforestry. Regular mesh grids were set up in these areas with 64 sample points spaced at 10 m from each other. At these points, we determined the particle size composition, soil resistance to penetration, moisture, soil bulk density and... Tipo: Info:eu-repo/semantics/article Palavras-chave: Sample density; Spatial variability; Physical properties; Scaled semivariograms. Ano: 2015 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832015000100021 A Classification for a Geostatistical Index of Spatial Dependence Rev. Bras. Ciênc. Solo Seidel,Enio Júnior; Oliveira,Marcelo Silva de. ABSTRACT: In geostatistical studies, spatial dependence can generally be described by means of the semivariogram or, in complementary form, with a single index followed by its categorization to classify the degree of such dependence. The objective of this study was to construct a categorization for the spatial dependence index (SDI) proposed by Seidel and Oliveira (2014) in order to classify spatial variability in terms of weak, moderate, and strong dependence. Theoretical values were constructed from different degrees of spatial dependence, which served as a basis for calculation of the SDI. In view of the form of distribution and SDI descriptive measures, we developed a categorization for posterior classification of spatial dependence, specific to each... Tipo: Info:eu-repo/semantics/article Palavras-chave: Geostatistics; Spatial dependence; Spatial variability; Semivariogram; Summary measures. Ano: 2016 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832016000100313 Water storage variability in a vineyard soil in the southern highlands of Santa Catarina state Rev. Bras. Ciênc. Solo Luciano,Rodrigo Vieira; Albuquerque,Jackson Adriano; Mafra,Álvaro Luiz; Costa,André da; Grah,Josué. In the subtropical regions of southern Brazil, rainfall distribution is uneven, which results in temporal variability of soil water storage. For grapes, water is generally available in excess and water deficiency occurs only occasionally. Furthermore, on the Southern Plateau of Santa Catarina, there are differences in soil properties, which results in high spatial variability. These two factors affect the composition of wine grapes. Spatio-temporal analyses are therefore useful in the selection of cultural practices as well as of adequate soils for vineyards. In this way, well-suited areas can produce grapes with a more appropriate composition for the production of quality wines. The aim of this study was to evaluate the spatio-temporal variability of... Tipo: Info:eu-repo/semantics/article Palavras-chave: Cambisol; Vitis vinifera L.; Geostatistics; Spatial variability; Temporal variability. Ano: 2014 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832014000100008 Slash Spatial Linear Modeling: Soybean Yield Variability as a Function of Soil Chemical Properties Rev. Bras. Ciênc. Solo Fagundes,Regiane Slongo; Uribe-Opazo,Miguel Angel; Guedes,Luciana Pagliosa Carvalho; Galea,Manuel. ABSTRACT: In geostatistical modeling of soil chemical properties, one or more influential observations in a dataset may impair the construction of interpolation maps and their accuracy. An alternative to avoid the problem would be to use most robust models, based on distributions that have heavier tails. Therefore, this study proposes a spatial linear model based on the slash distribution (SSLM) in order to characterize the spatial variability of soybean yields as a function of soil chemical properties. The likelihood ratio statistic (LR) was applied to verify the significance of parameters associated with the model. We evaluated the sensitivity of the maximum likelihood estimators by means of local influence analysis for both the soybean response and the... Tipo: Info:eu-repo/semantics/article Palavras-chave: Spatial variability; Slash distribution; Maximum likelihood; Yield estimators. Ano: 2018 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832018000100301 Strategy of specification of management areas: rice grain yield as related to soil fertility Rev. Bras. Ciênc. Solo Dalchiavon,Flávio Carlos; Carvalho,Morel de Passos e; Montanari,Rafael; Andreotti,Marcelo. It is well-known nowadays that soil variability can influence crop yields. Therefore, to determine specific areas of soil management, we studied the Pearson and spatial correlations of rice grain yield with organic matter content and pH of an Oxisol (Typic Acrustox) under no- tillage, in the 2009/10 growing season, in Selvíria, State of Mato Grosso do Sul, in the Brazilian Cerrado (longitude 51º24' 21'' W, latitude 20º20' 56'' S). The upland rice cultivar IAC 202 was used as test plant. A geostatistical grid was installed for soil and plant data collection, with 120 sampling points in an area of 3.0 ha with a homogeneous slope of 0.055 m m-1. The properties rice grain yield and organic matter content, pH and potential acidity and aluminum content were... Tipo: Info:eu-repo/semantics/article Palavras-chave: Precision agriculture; Soil fertility; Geostatistics; Spatial variability; Oryza sativa. Ano: 2013 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832013000100005 Inter-relation between soybean yield and soil compaction under degraded pasture in Brazilian Savannah Rev. Bras. Ciênc. Solo Queiroz,Rienni de Paula; Lazarini,Edson; Santos,Marcio Lustosa; Carvalho,Morel de Passos e; Santos,Cristiano. The Cerrado (Brazilian Savannah) plays an important economic and financial role in the nation, since the pastures of this biome feed cattle for half of the domestic bovine meat productivity, and its agricultural fields produce a third of the country's grain. The variability and spatial dependence between the soil physical attributes and soybean yield were evaluated in a crop rotation planted on a degraded brachiaria pasture, on a dystroferric Red Latosol of an experimental farm of the State University of São Paulo (UNESP), in the 2005/2006 growing season. The linear and spatial correlations between these attributes were also studied, to determine conditions that would allow increased agricultural productivity. In the above pasture area, a grid was... Tipo: Info:eu-repo/semantics/article Palavras-chave: Soil conservation; Crop rotation; Pasture management; Glycine max (L.) Merrill; Spatial variability. Ano: 2011 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832011000500012 Soil fertility, organic carbon and fractions of the organic matter at different distances from eucalyptus stumps Rev. Bras. Ciênc. Solo Faria,Geraldo Erli; Barros,Nairam Félix de; Novais,Roberto Ferreira; Silva,Ivo Ribeiro. Knowledge on variations in vertical, horizontal and temporal characteristics of the soil chemical properties under eucalyptus stumps left in the soil is of fundamental importance for the management of subsequent crops. The objective of this work was to evaluate the effect of eucalyptus stumps (ES) left after cutting on the spatial variability of chemical characteristics in a dystrophic Yellow Argisol in the eastern coastal plain region of Brazil. For this purpose, ES left for 31 and 54 months were selected in two experimental areas with similar characteristics, to assess the decomposition effects of the stumps on soil chemical attributes. Soil samples were collected directly around these ES, and at distances of 30, 60, 90, 120 and 150 cm away from them, in... Tipo: Info:eu-repo/semantics/article Palavras-chave: Nutrients; Humic substances; Spatial variability. Ano: 2009 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832009000300010 State-space approach to evaluate the relation between soil physical and chemical properties Rev. Bras. Ciênc. Solo Timm,L. C.; Reichardt,K.; Oliveira,J. C. M.; Cassaro,F. A. M.; Tominaga,T. T.; Bacchi,O. O. S.; Dourado-Neto,D.; Nielsen,D. R.. The state-space approach is used to evaluate the relation between soil physical and chemical properties in an area cultivated with sugarcane. The experiment was carried out on a Rhodic Kandiudalf in Piracicaba, State of São Paulo, Brazil. Sugarcane was planted on an area of 0.21 ha i.e., in 15 rows 100 m long, spaced 1.4 m. Soil water content, soil organic matter, clay content and aggregate stability were sampled along a transect of 84 points, meter by meter. The state-space approach is used to evaluate how the soil water content is affected by itself and by soil organic matter, clay content, and aggregate stability of neighboring locations, in different combinations, aiming to contribute to a better understanding of the relation among these variables in... Tipo: Info:eu-repo/semantics/article Palavras-chave: Spatial variability; Sugarcane crop; Kalman filter; Auto-regressive model. Ano: 2004 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832004000100005 Local influence for spatial analysis of soil physical properties and soybean yield using student's t-distribution Rev. Bras. Ciênc. Solo Assumpção,Rosangela Aparecida Botinha; Opazo,Miguel Angel Uribe; Galea,Manuel. The modeling and estimation of the parameters that define the spatial dependence structure of a regionalized variable by geostatistical methods are fundamental, since these parameters, underlying the kriging of unsampled points, allow the construction of thematic maps. One or more atypical observations in the sample data can affect the estimation of these parameters. Thus, the assessment of the combined influence of these observations by the analysis of Local Influence is essential. The purpose of this paper was to propose local influence analysis methods for the regionalized variable, given that it has n-variate Student's t-distribution, and compare it with the analysis of local influence when the same regionalized variable has n-variate normal... Tipo: Info:eu-repo/semantics/article Palavras-chave: Geostatistics; EM algorithm; Spatial variability. Ano: 2011 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832011000600008 Spatial and temporal distribution of weeds in no-tillage system AGRIAMBI Bottega,Eduardo L.; Pegoraro,Camilo; Guerra,Naiara; Oliveira Neto,Antonio M. de; Queiroz,Daniel M. de. ABSTRACT Brazil is one of the largest grain producers in the world, due to its extensive arable land and favorable climate for the cultivation of any species. The production could be higher, but problems such as competition between crops and weeds reduces crop yields. This study aimed to analyze the spatial distribution of weeds, especially milkweed (Sonchus oleraceus), horse weed (Conyza spp.) and ‘maria-mole’ (Senecio brasiliensis) in an area under no-tillage system for two harvests. The work was carried out during the 2013/14 and 2014/15 crop years in an area of 22.5 ha, where soybean is grown in the summer and oat in the winter. The weeds were mapped using a sampling grid of 85 points. The number of plants present in 0.25 m2 was recorded at each... Tipo: Info:eu-repo/semantics/article Palavras-chave: Precision agriculture; Spatial variability; Sonchus oleraceus; Conyza spp.; Senecio brasiliensis. Ano: 2016 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662016001201107 Determination of homogeneous zones for liming recommendations of black pepper using geostatistics AGRIAMBI Gontijo,Ivoney; Santos,Eduardo O. de J.; Partelli,Fábio L.; Gontijo,Andreia B. P. L.; Pires,Fábio R.. ABSTRACT Studies aimed at determining homogeneous zones and the spatial variability of soil characteristics may improve the efficiency of agricultural input applications. The purpose of this study was to determine homogeneous zones for liming applications and to characterize the spatial variability of characteristics related to soil acidity and productivity in an Oxisol cultivated with black pepper (Piper nigrum L.). This study was carried out in São Mateus, state of Espírito Santo, Brazil. The experimental site was 100 x 120 m. A grid with 126 sampling points was established. Three soil sub-samples were collected at each sampling point in the black pepper canopy areas, at a 0-0.20 m depth. Crop productivity was estimated by harvesting the three plants... Tipo: Info:eu-repo/semantics/article Palavras-chave: Piper nigrum L.; Spatial variability; Fertilization management. Ano: 2016 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662016001000918 Welfare and spatial distribution of noise levels in swine nursery AGRIAMBI Damasceno,Flavio A.; Oliveira,Carlos E. A.; Ferraz,Gabriel A. e S.; Nascimento,João A. C. do; Saraz,Jairo A. O.; Brandão,Leidimar F.. ABSTRACT The aim of this study was to evaluate the welfare and spatial distribution of noise levels in a swine nursery during the first three weeks of animal’s life. The climatic conditions were evaluated through the dry-bulb temperature (Tdb), relative humidity (RH) and black globe temperature and humidity index (BGHI) and allowed us to observe that the heating system influenced the conditions in the environment, and the use of the air conditioning system did not guarantee animal’s comfort conditions. The analysis on the spatial distribution of noise levels was performed using geostatistics and demonstrated the occurrence of spatial variability inside the facilities. The highest frequencies of noise levels were concentrated between 60 and 70 dB, and the... Tipo: Info:eu-repo/semantics/article Palavras-chave: Pig farming; Thermal comfort; Sound pressure; Spatial variability. Ano: 2019 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662019000300196 Registros recuperados: 73 Primeira ... 1 2 3 4 ... Última

Empresa Brasileira de Pesquisa Agropecuária - Embrapa Todos os direitos reservados, conforme Lei n° 9.610 Política de Privacidade Área restrita		Embrapa Parque Estação Biológica - PqEB s/n° Brasília, DF - Brasil - CEP 70770-901 Fone: (61) 3448-4433 - Fax: (61) 3448-4890 / 3448-4891 SAC: https://www.embrapa.br/fale-conosco