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Spatio-temporal variability behavior of land surface soil water content in shrub- and grass-land

HU, Wei; SHAO, Mingan; HAN, Fengpeng; REICHARDT, Klaus
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
Português
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56.26%
The knowledge of the relationship between spatial variability of the surface soil water content (theta) and its mean across a spatial domain (theta(m)) is crucial for hydrological modeling and understanding soil water dynamics at different scales. With the aim to compare the soil moisture dynamics and variability between the two land uses and to explore the relationship between the spatial variability of theta and theta(m), this study analyzed sets of surface theta measurements performed with an impedance soil moisture probe, collected 136 times during a period of one year in two transects covering different land uses, i.e., korshinsk peashrub transect (KPT) and bunge needlegrass transect (BNT), in a watershed of the Loess Plateau, China. Results showed that the temporal pattern of theta behaved similarly for the two land uses, with both relative wetter soils during wet period and relative drier soils during dry period recognized in BNT. Soil moisture tended to be temporally stable among different dates, and more stable patterns could be observed for dates with more similar soil water conditions. The magnitude of the spatial variation of theta in KPT was greater than that in ENT. For both land uses, the standard deviation (SD) of theta in general increased as theta(m) increased...

Mapeamento da variabilidade espacial das plantas daninhas com a utilização de ferramentas da agricultura de precisão.; Mapping weed spatial variability using precision farming tools.

Shiratsuchi, Luciano Shozo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 04/12/2001 Português
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66.28%
Tradicionalmente o manejo das plantas daninhas é realizado levando-se em consideração a infestação média destas plantas nas áreas agrícolas; sendo então adotadas estratégias de manejo de forma homogênea em toda a área. Porém, as plantas daninhas não se distribuem uniformemente, sendo comum o comportamento contagioso, formando manchas ou “reboleiras”. No entanto, a localização e mapeamento de diferentes infestações são tarefas difíceis de serem executadas em larga escala e requerem metodologias adequadas. Desta forma, métodos de determinação dessa variabilidade espacial necessitam de melhores esclarecimentos e estudos científicos. Com o objetivo de estudar o comportamento da variabilidade espacial das plantas daninhas e seu respectivo banco de sementes com a utilização de ferramentas da agricultura de precisão, foram realizados quatro experimentos para avaliar esta variabilidade espacial e temporal e analisar a potencialidade que a mesma pode proporcionar para o manejo racional das plantas daninhas, principalmente a possibilidade da aplicação localizada de herbicidas. O primeiro experimento consistiu do mapeamento do banco de sementes ao longo de dois anos consecutivos no intuito de comparar sua variabilidade espacial com a flora emergente. Concluiu-se que existe uma correlação entre o banco de sementes e a flora emergente e entre bancos de sementes de anos consecutivos...

Duração do período de molhamento foliar: medida com sensores eletrônicos, variabilidade espacial em culturas e estimativa com modelos empíricos; Leaf wetness duration: measurement with electronic sensors, spatial variability in crop canopies and estimation with empirical models

Santos, Eduardo Alvarez
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 01/09/2006 Português
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66.21%
A duração do período de molhamento (DPM) é de grande importância para a epidemiologia de doenças de plantas, pois desempenha papel fundamental em alguns processos epidemiológicos. Dessa forma, sua determinação torna-se indispensável para o entendimento da relação entre o clima e doenças de plantas. Sendo assim, este estudo teve como objetivos: definir uma posição padrão de instalação de sensores cilíndricos para a medida da DPM sobre gramado, avaliar a variabilidade espacial dessa variável em três diferentes culturas, relacionar a DPM medida em culturas agrícolas com aquela obtida em posto meteorológico e comparar a estimativa da DPM obtida com modelos empíricos com aquela medida com sensores eletrônicos. Na fase anterior à sua instalação no campo, todos os sensores eletrônicos foram previamente pintados com tinta látex e tratados termicamente. Após essa etapa, os sensores cilíndricos foram instalados sobre gramado a 30 cm de altura voltados para o sul. No período inicial, os sensores cilíndricos foram mantidos paralelos à horizontal, visando-se a avaliar a variabilidade entre os mesmos. Posteriormente, foram testados cinco diferentes ângulos de instalação. As medidas obtidas por esses sensores foram comparadas com a medida padrão...

Avaliação da variabilidade espacial do fallout do 'ANTPOT.7Be'; Evaluation of 'ANTPOT.7Be' fallout spatial variability

Pinto, Victor Meriguetti
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 19/09/2011 Português
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66.2%
O radioisótopo cosmogênico 'ANTPOT.7Be' é produzido por interações de partículas cósmicas com átomos da atmosfera, e vem sendo usado como traçador em estudos de erosão do solo e de processos climáticos. Após a formação, o 'ANTPOT.7Be' liga-se as partículas dos aerossóis presentes na atmosfera e é depositado na superfície terrestre com outras espécies de isótopos cosmogênicos pelas chuvas. Devido à grande afinidade com as partículas do solo e a meia vida curta de 53,2 dias, este radioisótopo acompanha os processos erosivos do solo e pode ser usado como traçador para estimar taxas de erosão e deposição de sedimentos durante um evento de chuva isolado ou conjunto de eventos de chuva erosivos de curta duração. Uma hipótese fundamental para a avaliação da redistribuição do solo através do 'ANTPOT.7Be' é a uniformidade da distribuição espacial do seu fallout. O método do 'ANTPOT.7Be' foi elaborado recentemente e por isso aplicado em poucas situações, de forma que muitos assuntos em relação ao método ainda não foram propriamente estudados, e algumas hipóteses, como da uniformidade do fallout do 'ANTPOT.7Be', precisam ser avaliadas. O principal objetivo deste estudo foi avaliar a distribuição espacial do fallout do 'ANTPOT.7Be' analisando-se as atividades dos 5 mm iniciais da água da chuva de eventos isolados. Os eventos de chuva foram amostrados em doze pontos de coleta distribuídos em uma área experimental de aproximadamente 300 m² e localizada no campus da Universidade de São Paulo...

Variabilidade espacial de componentes morfológicos e de produtividade da cultura de soja e suas relações com atributos químicos do solo; Spatial variability of morphological components and productivity of soybean and its relationship with chemical soil

Flora, Lisandra Pinto Della
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 03/09/2013 Português
Relevância na Pesquisa
56.26%
Após a primeira fase de implementação da agricultura de precisão, foram encontradas baixas correlações entre os atributos do solo e a produtividade da soja. Assim, o conhecimento da relação entre os componentes da planta, tais como componentes de produtividade, além de ser importante para a definição do tipo de planta mais produtiva, pode ajudar na compreensão dos fatores que regulam a produção de grãos de soja. Este estudo teve como objetivo avaliar as relações espaciais entre os componentes morfológicos e produtividade de soja com a variabilidade espacial de atributos do solo. A área experimental (117,17 ha) situa-se entre as latitudes de 26 ° 90 '27'' S e 27 ° 02' 86'' S (Sul) e as longitudes de 69 ° 30 '88'' W e 69 ° 32' 67'' W (Oeste), no município de Boa Vista das Missões, Estado do Rio Grande do Sul, Brasil. As variedades cultivadas utilizadas foram Nidera-5909-RG e Nidera-6411-RG nas safras 2010/2011 e 2011/2012, respectivamente. A área foliar foi estimada pelo método de discos no estádio fenológico V4 da cultura de soja. Amostras de solo e planta foram coletadas em 39 pontos georreferenciados com malha de amostragem regular de 173,73 x 173,73 m. Os dados de atributos químicos do solo apresentaram alta variabilidade espacial. O teor de argila...

Variabilidade espacial do solo em sistema plantio direto estabilizado; Spatial variability of soil in stabilized direct planting system

Duarte, Sara de Jesus
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 10/04/2015 Português
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66.2%
A homogeneidade do solo em sistema de plantio direto, é um assunto questionável, pois alguns autores têm considerado que, com o passar do tempo, há aumento da homogeneidade do solo, outros têm verificado a redução. A hipótese deste trabalho é que em sistema de plantio direto consolidado existe correlação e dependência espacial dos atributos físicos-hídrico do solo e do desenvolvimento vegetativo da soja, sendo a cokrigagem colocalizada interpolador mais representativo destas correlações. O objetivo foi avaliar a variabilidade espacial de atributos físicos do solo e do desenvolvimento vegetativo da soja em sistema de plantio direto, adotado há mais de 19 anos. O trabalho foi desenvolvido na fazenda-escola da Universidade Estadual de Ponta Grossa - Paraná. A área de estudo tem como cultura a soja e está inserida em um relevo cuja declividade máxima, no sentido da pendente, é de aproximadamente 10 %. Nesta área, foram avaliados atributos físicos e hídrico do solo, como: densidade do solo (Ds), granulometria (areia e argila) e condutividade hidráulica saturada (Kfs). Avaliou-se, ainda, atributos de planta: altura da planta, estádio reprodutivo e stand. Para tais avaliações, foi demarcado um grid com espaçamento 10 x 10 metros...

Possible causes of spatial variability in Diatraea saccharalis Fabr. (Lep., Crambidae) and its parasitoid populations in sugarcane fields in Brazil

Rossi, M. N.
Fonte: Blackwell Verlag Gmbh Publicador: Blackwell Verlag Gmbh
Tipo: Artigo de Revista Científica Formato: 494-500
Português
Relevância na Pesquisa
66.25%
Based on the large data set stored in some sugarcane mills regarding the biological control programme of Diatraea saccharalis using the parasitoids Cotesia flavipes and tachinid flies, the aim of the present study was to determine whether sugarcane varieties, number of cuts and plant ages are major determinants in promoting spatial variability in D. saccharalis, C. flavipes and tachinid fly populations in sugarcane fields in the state of São Paulo (Brazil). The data set used to support this study was provided by the Sao Joao and Barra sugarcane mills. Coefficient of variation was adopted as a measure of the spatial variability of population density. Spatial variability was estimated for the total density of D. saecharalis (parasitized + unparasitized larvae), and also for D. saccharalis larvae parasitized by tachinids and by C. flavipes. Statistical analysis revealed that the spatial variation in D. saccharalis populations was influenced by the number of cuts and by plant ages in the Barra and Sao Joao Mills, respectively. Similar results were obtained for D. saccharalis larvae parasitized by tachinids; however, in the Sao Joao Mill, the spatial variability of these populations was also influenced by the different number of varieties. Finally...

Short-term temporal changes in the spatial variability model of CO2 emissions from a Brazilian bare soil

La Scala, N.; Marques, J.; Pereira, G. T.; Cora, J. E.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 1459-1462
Português
Relevância na Pesquisa
66.14%
In this work, the spatial variability model of CO2 emissions and soil properties of a Brazilian bare soil were investigated. Carbon dioxide emissions were measured on three different days at contrasted soil temperature and soil moisture conditions, and soil properties were investigated at the same points where emissions were measured. One spatial variability model of soil CO2 emissions was found for each measurement day, and these models are similar to the ones of soil properties studied in an area of 100 x 100 m. (C) 2000 Elsevier B.V. Ltd. All rights reserved.

Evaluation of Maize Yield Spatial Variability based on Field Flow Density

Marques da Silva, José Rafael; Silva, Luis Leopoldo
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica Formato: 9299 bytes; application/pdf
Português
Relevância na Pesquisa
66.23%
Maize yield is affected by water availability, which varies with field topography. The analysis of yield data obtained in different field landscape positions allows the spatial patterns of crop yield to be identified and related to field attributes, helping the spatial management of fields to be improved. The relationship between distance to flow accumulation lines (DFL) and spatial variability of yield and grain moisture at harvest has already been identified in a previous work by the authors. The main objective of this study is to confirm the relationship between DFL and spatial variability of yield and grain moisture at harvest, and also to establish a relationship between a field hydrological attribute (flow density) and average yield and distance to nearest flow accumulation line. The study was conducted using data collected from three agricultural fields (30,40 and 60 ha) irrigated by centre-pivot systems, in Southern Portugal, over a 3 yr period from 2002 to 2004.Collected data were divided into data sets corresponding to nine classes of DFL. Total flow lines length (SFLL) was used to calculate flow density (Fd). Based on these data sets, the relationship between yield and grain moisture at harvest and DFL and flow density was analysed. Coefficients of determination were very high (significant R2 from 0.91 to 0.98) for almost every year of the experiment...

Analysis of the spatial variability of crop yield and soil properties in small agricultural plots

Vieira,Sidney Rosa; Paz Gonzalez,Antonio
Fonte: Instituto Agronômico de Campinas Publicador: Instituto Agronômico de Campinas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2003 Português
Relevância na Pesquisa
66.17%
The objective of this study was to assess spatial variability of soil properties and crop yield under no tillage as a function of time, in two soil/climate conditions in São Paulo State, Brazil. The two sites measured approximately one hectare each and were cultivated with crop sequences which included corn, soybean, cotton, oats, black oats, wheat, rye, rice and green manure. Soil fertility, soil physical properties and crop yield were measured in a 10-m grid. The soils were a Dusky Red Latossol (Oxisol) and a Red Yellow Latossol (Ultisol). Soil sampling was performed in each field every two years after harvesting of the summer crop. Crop yield was measured at the end of each crop cycle, in 2 x 2.5 m sub plots. Data were analysed using semivariogram analysis and kriging interpolation for contour map generation. Yield maps were constructed in order to visually compare the variability of yields, the variability of the yield components and related soil properties. The results show that the factors affecting the variability of crop yield varies from one crop to another. The changes in yield from one year to another suggest that the causes of variability may change with time. The changes with time for the cross semivariogram between phosphorus in leaves and soybean yield is another evidence of this result.

Spatial variability of the chemical, physical and biological properties in lowland cultivated with irrigated rice

Parfitt,José Maria Barbat; Timm,Luís Carlos; Pauletto,Eloy Antonio; Sousa,Rogério Oliveira de; Castilhos,Danilo Dufech; Ávila,Conceição Lagos de; Reckziegel,Nestor Luis
Fonte: Sociedade Brasileira de Ciência do Solo Publicador: Sociedade Brasileira de Ciência do Solo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2009 Português
Relevância na Pesquisa
56.23%
In the areas where irrigated rice is grown in the south of Brazil, few studies have been carried out to investigate the spatial variability structure of soil properties and to establish new forms of soil management as well as determine soil corrective and fertilizer applications. In this sense, this study had the objective of evaluating the spatial variability of chemical, physical and biological soil properties in a lowland area under irrigated rice cultivation in the conventional till system. For this purpose, a 10 x 10 m grid of 100 points was established, in an experimental field of the Embrapa Clima Temperado, in the County of Capão do Leão, State of Rio Grande do Sul. The spatial variability structure was evaluated by geostatistical tools and the number of subsamples required to represent each soil property in future studies was calculated using classical statistics. Results showed that the spatial variability structure of sand, silt, SMP index, cation exchange capacity (pH 7.0), Al3+ and total N properties could be detected by geostatistical analysis. A pure nugget effect was observed for the nutrients K, S and B, as well as macroporosity, mean weighted diameter of aggregates, and soil water storage. The cross validation procedure...

Water storage variability in a vineyard soil in the southern highlands of Santa Catarina state

Luciano,Rodrigo Vieira; Albuquerque,Jackson Adriano; Mafra,Álvaro Luiz; Costa,André da; Grah,Josué
Fonte: Sociedade Brasileira de Ciência do Solo Publicador: Sociedade Brasileira de Ciência do Solo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2014 Português
Relevância na Pesquisa
56.21%
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 water storage in a Cambisol during the growth cycle of a Cabernet Sauvignon vineyard and its relation to selected soil properties. The experimental area consisted of a commercial 8-year-old vineyard in São Joaquim, Santa Catarina, Brazil. A sampling grid with five rows and seven points per row, spaced 12 m apart, was outlined on an area of 3,456 m². Soil samples were collected with an auger at these points, 0.30 m away from the grapevines, in the 0.00-0.30 m layer, to determine gravimetric soil moisture. Measurements were taken once a week from December 2008 to April 2009...

Soil spatial variability and the estimation of the irrigation water depth

Reichardt,Klaus; Silva,José Carlos de Araújo; Bassoi,Luis Henrique; Timm,Luís Carlos; Oliveira,Julio Cesar Martins de; Bacchi,Osny Oliveira Santos; Pilotto,João Eduardo
Fonte: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz" Publicador: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz"
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2001 Português
Relevância na Pesquisa
66.1%
The effects of soil water spatial variability previous to irrigation and of the field capacity on the estimation of irrigation water depth are evaluated. The experiment consisted of a common bean (Phaseolus vulgaris L.) crop established on a Kandiudalfic Eutrudox of Piracicaba, SP, Brazil, irrigated by central pivot, in which soil water contents were evaluated with a depth neutron gauge, in a grid of 20x4 points with lag of 0.5 m. In a given situation, the 80 calculated irrigation water depths presented a coefficient of variation of 29.3%, with an average water value of 18 mm, maximum of 41mm and minimum of 9 mm. It is concluded that the only practical way of irrigation is the use of an average water depth, due to the inherent variability of the soil, and that the search for better field capacity values does not imply in better water depth estimates.

Random and systematic spatial variability of 137Cs inventories at reference sites in South-Central Brazil

Correchel,Vladia; Bacchi,Osny Oliveira Santos; Reichardt,Klaus; De Maria,Isabella Clerici
Fonte: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz" Publicador: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz"
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2005 Português
Relevância na Pesquisa
56.21%
The precision of the 137Cs fallout redistribution technique for the evaluation of soil erosion rates is strongly dependent on the quality of an average inventory taken at a representative reference site. The knowledge of the sources and of the degree of variation of the 137Cs fallout spatial distribution plays an important role on its use. Four reference sites were selected in the South-Central region of Brazil which were characterized in terms of soil chemical, physical and mineralogical aspects as well as the spatial variability of 137Cs inventories. Some important differences in the patterns of 137Cs depth distribution in the soil profiles of the different sites were found. They are probably associated to chemical, physical, mineralogical and biological differences of the soils but many questions still remain open for future investigation, mainly those regarding the adsorption and dynamics of the 137Cs ions in soil profiles under tropical conditions. The random spatial variability (inside each reference site) was higher than the systematic spatial variability (between reference sites) but their causes were not clearly identified as possible consequences of chemical, physical, mineralogical variability, and/or precipitation.

Fun????es de pedotransfer??ncia e estrutura de variabilidade espacial da reten????o de ??gua em solos de v??rzea do Rio Grande do Sul; Pedotransfer functions and spatial variability of water retention in lowland soils of Rio Grande do Sul state

NEBEL, ??lvaro Luiz Carvalho
Fonte: Universidade Federal de Pelotas; Agronomia; Programa de P??s-Gradua????o em Solos; UFPel; BR Publicador: Universidade Federal de Pelotas; Agronomia; Programa de P??s-Gradua????o em Solos; UFPel; BR
Tipo: Tese de Doutorado Formato: application/pdf
Português
Relevância na Pesquisa
66.14%
The understanding of the dynamics of the water in the soil-plant-atmosphere system, including the water availability to the crops, soil water infiltration, drainage and soil solute movement, depends on the knowledge of the relation between the soil water content and the matric potential, represented by the soil water retention curve (SWRC). However, the establishment of SWRCs is laborious and time consuming, besides being costly. A alternative is its estimate through statistical equations called Pedotransfer Functions (PTFs). The aim of this study was to evaluate the ability of some existing PTFs, in predicting the soil water retention and to capture its spatial variability structure, using geostatistical tools, when applied in a lowland soil of the south region of Brazil. For this, an experimental 10 x 10 m grid was established and soil disturbed and undisturbed samples were collected in the 0-0.20 m soil depth, totaling 100 experimental points. The following soil attributes were determined in each point: soil texture, soil organic carbon, pH, cation exchange capacity, soil bulk density, and the soil water retention curve. Eight developed PTFs for estimating gravimetric soil water content, eight for estimating volumetric water content and five for estimating the van Genuchten model parameters were evaluated using the statistical measures mean error (ME)...

APPLICATION OF GEOMATICS TECHNOLOGIES TO CHARACTERIZE SPATIAL VARIABILITY AT STRATUS VINEYARDS

Tasker, Victoria
Fonte: Brock University Publicador: Brock University
Português
Relevância na Pesquisa
66.28%
Vineyards vary over space and time, making geomatics technologies ideally suited to study terroir. This study applied geomatics technologies - GPS, remote sensing and GIS - to characterize the spatial variability at Stratus Vineyards in the Niagara Region. The concept of spatial terroir was used to visualize, monitor and analyze the spatial and temporal variability of variables that influence grape quality. Spatial interpolation and spatial autocorrelation were used to measure the pattern demonstrated by soil moisture, leaf water potential, vine vigour, soil composition and grape composition on two Cabernet Franc blocks and one Chardonnay block. All variables demonstrated some spatial variability within and between the vineyard block and over time. Soil moisture exhibited the most significant spatial clustering and was temporally stable. Geomatics technologies provided valuable spatial information related to the natural spatial variability at Stratus Vineyards and can be used to inform and influence vineyard management decisions.

Representing spatial variability of snow water equivalent in hydrologic and land-surface models: a review

Clark, M.; Hendrikx, J.; Slater, A.; Kavetski, D.; Anderson, B.; Cullen, N.; Kerr, T.; Hreinsson, E.; Woods, R.
Fonte: Amer Geophysical Union Publicador: Amer Geophysical Union
Tipo: Artigo de Revista Científica
Publicado em //2011 Português
Relevância na Pesquisa
66.3%
This paper evaluates the use of field data on the spatial variability of snow water equivalent (SWE) to guide the design of distributed snow models. An extensive reanalysis of results from previous field studies in different snow environments around the world is presented, followed by an analysis of field data on spatial variability of snow collected in the headwaters of the Jollie River basin, a rugged mountain catchment in the Southern Alps of New Zealand. In addition, area-averaged simulations of SWE based on different types of spatial discretization are evaluated. Spatial variability of SWE is shaped by a range of different processes that occur across a hierarchy of spatial scales. Spatial variability at the watershed-scale is shaped by variability in near-surface meteorological fields (e.g., elevation gradients in temperature) and, provided suitable meteorological data is available, can be explicitly resolved by spatial interpolation/extrapolation. On the other hand, spatial variability of SWE at the hillslope-scale is governed by processes such as drifting, sloughing of snow off steep slopes, trapping of snow by shrubs, and the nonuniform unloading of snow by the forest canopy, which are more difficult to resolve explicitly. Subgrid probability distributions are often capable of representing the aggregate-impact of unresolved processes at the hillslope-scale...

Analysis of the spatial variability of crop yield and soil properties in small agricultural plots

Vieira, Sidney Rosa; Paz González, Antonio
Fonte: Instituto Agronômico de Campinas Publicador: Instituto Agronômico de Campinas
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
66.17%
The objective of this study was to assess spatial variability of soil properties and crop yield under no tillage as a function of time, in two soil/climate conditions in São Paulo State, Brazil. The two sites measured approximately one hectare each and were cultivated with crop sequences which included corn, soybean, cotton, oats, black oats, wheat, rye, rice and green manure. Soil fertility, soil physical properties and crop yield were measured in a 10-m grid. The soils were a Dusky Red Latossol (Oxisol) and a Red Yellow Latossol (Ultisol). Soil sampling was performed in each field every two years after harvesting of the summer crop. Crop yield was measured at the end of each crop cycle, in 2 x 2.5 m sub plots. Data were analysed using semivariogram analysis and kriging interpolation for contour map generation. Yield maps were constructed in order to visually compare the variability of yields, the variability of the yield components and related soil properties. The results show that the factors affecting the variability of crop yield varies from one crop to another. The changes in yield from one year to another suggest that the causes of variability may change with time. The changes with time for the cross semivariogram between phosphorus in leaves and soybean yield is another evidence of this result.

Variabilidade espacial do solo e a estimativa da lâmina de irrigação; Soil spatial variability and the estimation of the irrigation water depth

Reichardt, Klaus; Silva, José Carlos de Araújo; Bassoi, Luis Henrique; Timm, Luís Carlos; Oliveira, Julio Cesar Martins de; Bacchi, Osny Oliveira Santos; Pilotto, João Eduardo
Fonte: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz Publicador: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; Formato: application/pdf
Publicado em 01/09/2001 Português
Relevância na Pesquisa
66.1%
A influência da variabilidade espacial da umidade do solo em uma situação pré-irrigação e da capacidade de campo é avaliada no cálculo da lâmina de irrigação. O experimento constou de cultura de feijão (Phaseolus vulgaris L.) estabelecida em um ARGISSOLO da região de Piracicaba, SP, irrigada por pivô central, tendo as medidas de umidade sido feitas com sonda de nêutrons, em uma malha de 20x4 pontos, espaçados de 0.5 m. Em determinada situação, os 80 valores de lâmina de irrigação calculados apresentaram um coeficiente de variação de 29.3%, para uma média de 18 mm, com valor mínimo de 9 mm e máximo de 41mm. É concluído que a única forma prática de irrigação é o uso de uma lâmina média devido à variabilidade inerente ao solo, e que a procura de melhores valores para a capacidade de campo não implica em melhores estimativas da lâmina de irrigação.; The effects of soil water spatial variability previous to irrigation and of the field capacity on the estimation of irrigation water depth are evaluated. The experiment consisted of a common bean (Phaseolus vulgaris L.) crop established on a Kandiudalfic Eutrudox of Piracicaba, SP, Brazil, irrigated by central pivot, in which soil water contents were evaluated with a depth neutron gauge...

Geostatistical simulation of spatial variability of convective storms in Mexico City Valley

Méndez-Venegas,Javier; Díaz-Viera,Martín A.; Herrera,Graciela S.; Valdés-Manzanilla,Arturo
Fonte: Instituto de Geofísica, UNAM Publicador: Instituto de Geofísica, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2013 Português
Relevância na Pesquisa
66.18%
Precipitation is one of the main components of the hydrological cycle and knowledge of its spatial distribution is fundamental for the prediction of other closely related environmental variables, for example, runoff, flooding and aquifer recharge. Most of the precipitation in Mexico City is due to convective storms characterized by a high spatial variability, implying that modeling its behavior is very complex. In this work stochastic simulation techniques with a geostatistical approach were applied to model the spatial variability of the rainfall of three convective storms. The analysis of the results shows that using the proposed methodology spatial distributions of rain are obtained that reproduce the statistical characteristics present in the available information.