Biophysical characteristics of soybean estimated by remote sensing associated with artificial intelligence

The biophysical characteristics of vegetative canopies, such as biomass, height, and canopy diameter, are of paramount importance for the study of the development and productive behavior of crops. Faced with a scarcity of studies aimed at estimating these parameters, the objective of this study was to evaluate the performance of artificial neural networks (ANNs) applied to Proximal Remote Sensing (PRS) to estimate biophysical characteristics of soybean culture. The data used to train and validate the ANNs came from an experiment composed of 65 plots with 30 x 30 m mesh, its development was carried out in the 2016/2017 crop in the Brazilian agricultural area. The evaluations were carried out at 30, 45, 60, and 75 days after sowing (DAS), monitoring the spatial and temporal variability of the biophysical characteristics of the soybean crop. Vegetation indexes were collected using canopy sensors. The accuracy and precision were determined by the coefficient of determination (R2) and the error of the forecasts by MAPE (Mean Absolute Percentage Error). PRS and ANNs showed high potential for application in agriculture, since they obtained good performance in the estimation of height (R2 = 0.89) and canopy diameter (R2 = 0.96), being fresh biomass (R2 =0.98) and dry biomass (R2 = 0.97) were the best-estimated variables.

Association of greenness surrounding schools and homes with adiposity levels in children and adolescents / 环境与职业医学

Background Evidence on the association between greenness and adiposity in children and adolescents is inconsistent and mostly from developed countries. Relatively limited evidence is from China. Objective To assess the association between greenness and adiposity in children and adolescents based on satellite remote sensing data. Methods From 2016 to 2018, a cross-sectional study was conducted among 52316 children and adolescents aged 5-18 years in three cities in the Pearl River Delta region of China. Basic sociological and demographic characteristics of the population and adiposity levels were collected through questionnaires. Land Remote-Sensing Satellite (Landsat) data and moderate-resolution imaging spectroradiometer (MODIS) products were used to quantify the greenness around the schools and homes, including normalized difference vegetation index (NDVI), vegetation continuous field (VCF), soil-adjusted vegetation index (SAVI), and enhanced vegetation index (EVI) calculated within 500 m and 1000 m buffers centered around the participants' homes or schools. A restricted cubic spline function was used to assess the exposure-response relationship. After categorizing greenness levels into quartiles with the first quartile as the reference, two-level generalized linear models were applied to assess the change in body mass index z-scores (zBMI) and the risk of overweight of children and adolescents in higher quartiles relative to the lowest quartile. In addition, counterfactual framework modelling was applied to assess the potential mediation effects of PM2.5 and NO2, and physical activity levels on the associations between greenness and adiposity levels. Results Of the 52316 children included, 8406 (16.1%) were overweight. A non-linear negative association of the level of greenness around the homes or schools and zBMI was found, with a significant lower zBMI in children and adolescents when a certain level of greenness was reached. After adjusting for confounders, the participants in the highest quartile had a significantly lower level of zBMI and a significantly lower risk of overweight compared with those in the lowest quartile of NDVI500 m and VCF500 m. The estimate change (\begin{document}$b$\end{document}) for zBMI was −0.07 (95%CI: −0.10-−0.04) and the odds ratio (OR) for overweight was 0.92 (95%CI: 0.85-0.99) for the students in the highest NDVI500 m quartile based on home address compared to those in the lowest quartile. Significant negative associations were also observed when 1000 m buffer, SAVI, and EVI were used. The mediation analysis showed that PM2.5 and NO2 partially mediated the negative association of NDVI500 m with zBMI , and the proportions of mediation were 50% (95%CI: 20%-80%) and 90% (95%CI: 50%-160%), respectively while no significant mediation effect was observed for physical activity level. Conclusion Higher levels of greenness surrounding homes or schools may be associated with a reduced risk of overweight and decreased zBMI in children and adolescents, and such associations may be partially mediated by reducing air pollutant concentrations.

Influencia del ángulo de iluminación solar y la altura de la toma de la imagen multiespectral sobre la estimación de biomasa de pasto kikuyo / Influence of height and zenith angle of multispectral images on the estimation of kikuyo grass biomass

RESUMEN El objetivo de este estudio fue analizar la influencia del ángulo cenital de iluminación solar (mañana, mediodía y tarde) y la distancia (entre 10 y 50m) de imágenes multiespectrales de praderas de kikuyo, para la estimación de biomasa. Se capturaron datos espectrales de 40 muestras y se les calculó el índice de vegetación normalizada (NDVI) y la biomasa del forraje de las áreas fotografiadas. La relación de la biomasa con el NDVi, se hizo mediante modelos aditivos generalizados. Se encontró que es posible predecir la cantidad de biomasa con imágenes tomadas al mediodía y las alturas de vuelo analizadas (con R2 =0,99), indicando que el monitoreo de praderas puede incorporar información de sensores con bandas de rojo e infrarrojo cercano, tomadas entre las 12:00m y 1:00pm.

ABSTRACT The objective of this study was to analyze the effect of solar zenith angle (morning, noon and afternoon) and the distance (between 10 and 50m) of the multispectral images of kikuyo grasslands for biomass estimation. Spectral data from 40 samples were captured and the normalized vegetation index (NDVI) and the forage biomass of the photographed areas were calculated. The relationship of the biomass with the NDVi was made using generalized additive models. It was found that it is possible to predict the amount of biomass with images taken at noon and the flight heights analyzed (with R2 = 0.99), indicating that grassland monitoring can incorporate sensor information with red and near infrared bands taken between 12:00m and 1:00 pm.

Environmental risk factors of leishmaniasis in Bahia State, Brazil using NASA Earth observation satellites / Fatores de risco ambientais para leishmanioses no estado da Bahia, Brasil, utilizando satélites da NASA de observação da Terra

NASA's Earth Observing Satellites (EOS) were used to calculate three vegetation indices, extract precipitation and elevation data, and then evaluate their applicability for assessing risk of visceral leishmaniasis (VL) and cutaneous leishmaniasis (CL) in Bahia State, Brazil. Regression models showed that either form of leishmaniasis can be predicted by NDVI, NDMI, NDWI data products and TRMM) precipitation data (R2= 0.370; p<0.001). Elevation was not significantly associated with the distribution of either VL or CL. In areas of high annual precipitation, CL was 3.6 times more likely to occur than VL. For vegetative moisture (NDMI), CL was 2.11 times more likely to occur than VL. Odds of CL occurrence increased to 5.5 times when vegetation (NDVI) and 13.5 times when liquid water content of vegetation canopies (NDWI) was considered. Areas at risk of CL and VL were mapped based on the selected explanatory variables. Accuracy of models were assessed using area under the receiver operating characteristic curve (AUC=0.72). We propose that statewide scale risk models based on use of EOS products will be a useful tool at 1 km2 spatial resolution to enable health workers to identify and target high risk areas to prevent transmission of leishmaniasis.(AU)

Os satélites de observação da Terra (SOT) da NASA foram usados para calcular três índices de vegetação, extrair dados de precipitação e elevação e avaliar sua aplicabilidade para identificar o risco para leishmaniose visceral (LV) e leishmaniose tegumentar (LT) no Estado da Bahia, Brasil. Modelos de regressão mostraram que ambas as formas de leishmaniose podem ser preditas pelos NDVI, NDMI, NDWI e precipitação TRMM (R2 = 0,370; p<0,001). A elevação não foi significativamente associada à distribuição de LV ou LT. Em áreas de alta precipitação anual, a LT foi 3,6 vezes mais provável de ocorrer do que a LV. Para a umidade vegetativa (NDMI), a LT apresentou 2,11 maior probabilidade de ocorrer do que a LV. As chances de ocorrência de LT aumentaram para 5,5 vezes em relação com a vegetação (NDVI) e 13,5 vezes quando o conteúdo de água líquida dos dosséis da vegetação (NDWI) foi considerado. Áreas em risco de LT e LV foram mapeadas com base nas variáveis explicativas selecionadas. A precisão dos modelos foi avaliada usando a área sob curva característica de operação do receptor (Curva COR=0,72). Propusemos que os modelos de risco em escala estadual baseados no uso de produtos SOT são uma ferramenta útil na resolução espacial de 1 km2 por permitir que profissionais de saúde identifiquem e direcionem áreas de alto risco para evitar a transmissão da leishmaniose. (AU)

Environmental risk factors of leishmaniasis in Bahia State, Brazil using NASA Earth observation satellites / Fatores de risco ambientais para leishmanioses no estado da Bahia, Brasil, utilizando satélites da NASA de observação da Terra

NASA’s Earth Observing Satellites (EOS) were used to calculate three vegetation indices, extract precipitation and elevation data, and then evaluate their applicability for assessing risk of visceral leishmaniasis (VL) and cutaneous leishmaniasis (CL) in Bahia State, Brazil. Regression models showed that either form of leishmaniasis can be predicted by NDVI, NDMI, NDWI data products and TRMM) precipitation data (R2 = 0.370; p<0.001). Elevation was not significantly associated with the distribution of either VL or CL. In areas of high annual precipitation, CL was 3.6 times more likely to occur than VL. For vegetative moisture (NDMI), CL was 2.11 times more likely to occur than VL. Odds of CL occurrence increased to 5.5 times when vegetation (NDVI) and 13.5 times when liquid water content of vegetation canopies (NDWI) was considered. Areas at risk of CL and VL were mapped based on the selected explanatory variables. Accuracy of models were assessed using area under the receiver operating characteristic curve (AUC=0.72). We propose that statewide scale risk models based on use of EOS products will be a useful tool at 1 km2 spatial resolution to enable health workers to identify and target high risk areas to prevent transmission of leishmaniasis.

Os satélites de observação da Terra (SOT) da NASA foram usados para calcular três índices de vegetação, extrair dados de precipitação e elevação e avaliar sua aplicabilidade para identificar o risco para leishmaniose visceral (LV) e leishmaniose tegumentar (LT) no Estado da Bahia, Brasil. Modelos de regressão mostraram que ambas as formas de leishmaniose podem ser preditas pelos NDVI, NDMI, NDWI e precipitação TRMM (R2 = 0,370; p<0,001). A elevação não foi significativamente associada à distribuição de LV ou LT. Em áreas de alta precipitação anual, a LT foi 3,6 vezes mais provável de ocorrer do que a LV. Para a umidade vegetativa (NDMI), a LT apresentou 2,11 maior probabilidade de ocorrer do que a LV. As chances de ocorrência de LT aumentaram para 5,5 vezes em relação com a vegetação (NDVI) e 13,5 vezes quando o conteúdo de água líquida dos dosséis da vegetação (NDWI) foi considerado. Áreas em risco de LT e LV foram mapeadas com base nas variáveis explicativas selecionadas. A precisão dos modelos foi avaliada usando a área sob curva característica de operação do receptor (Curva COR=0,72). Propusemos que os modelos de risco em escala estadual baseados no uso de produtos SOT são uma ferramenta útil na resolução espacial de 1 km2 por permitir que profissionais de saúde identifiquem e direcionem áreas de alto risco para evitar a transmissão da leishmaniose.

Space-temporal evaluation of changes in temperature and soil use and cover in the metropolitan region of baixada santista / Avaliação espaço-temporal das mudanças do uso e cobertura do solo e temperatura na região metropolitana da baixa da santista

The Metropolitan Region of Baixada Santista (MRBS) harbors one of the main port areas of Brazil: the Port of Santos. Due to the accelerated urban development in this region, the monitoring of biophysical parameters is fundamental. Therefore, this paper aims to i) estimate the soil surface temperature (Ts) and identify the Urban Heat Islands (UHI) formation; and ii) compare the Ts and the normalized difference vegetation index (NDVI) for MRBS from 1986 to 2016 using Landsat 5 and 8 images. Remote sensing tools are essential to meet the objectives of this work for providing both the spatial and temporal evaluation of a region. The spatial analysis was based on the NDVI to evaluate the vegetation density and size from five previously established classes (i.e., water bodies, urban grid, exposed soil and road corridors, shrub, and dense vegetation). The NDVI mapping showed a significant reduction in the cover area referred to the dense vegetation class (91.7%), while the urban grid category increased by 29.4%, resulting from the urban expansion and green cover reduction over the region during this period. Surface temperature thematic maps showed high-temperature values related to increased urbanization and decreased rainfall. Moreover, an 8°C rise in surface temperature over the last 30 years was registered due to the regional development, which has replaced natural soils by anthropic materials and reduced dense vegetation. This phenomenon has resulted in the formation and intensification of UHI, especially after the 2000s.

A Região Metropolitana da Baixada Santista (RMBS) abriga uma das principais zonas portuárias do Brasil, o Porto de Santos. Devido ao grau de urbanização dessa região, o monitoramento dos parâmetros biofísicos torna-se fundamental. Desta forma, este estudo tem como objetivo i) estimar a Temperatura de superfície terrestre (Ts) da RMBS, seguido da identificação da formação de ICU e ii) relacionar a Ts e o NDVI da RMBS no período de 1986 a 2016, a partir das imagens do Landsat 5 e 8. A análise espacial foi baseada no Normalized Difference Vegetation Index (NDVI), no sentido de verificar as condições da densidade e porte da vegetação a partir de cinco classes previamente estabelecidas (Corpo d'água, Malha urbana, Solo exposto e corredores viários, Substrato Arbustivo e Vegetação densa). Os mapas de NDVI indicam uma redução significativa na área de cobertura correspondente à classe vegetação densa, com o valor de cobertura de 91,7%. Por outro lado, a classe Malha urbana apresentou um aumento de 29,4%, resultantes da expansão urbana e da redução da cobertura verde na RMBS ao longo do período. Os mapas temáticos de Tsmostraram altos valores de temperatura, relacionados ao aumento da malha urbana e redução da precipitação. Além disso, houve um aumento de 8ºC na Ts nos últimos 30 anos, causados pelo avanço do desenvolvimento regional, associados à substituição do solo natural por materiais antrópicos e à redução da vegetação densa. Esses fatores resultaram no surgimento de ICU e sua intensificação a partir dos anos 2000.

QTL mapping for morphological and physiological traits in RILs of spring wheat population of WH1021 × WH711

Aim: To identify the quantitative trait loci (QTLs) associated with various morphological and physiological traits. Methodology: A recombinant inbred line (RIL) population of wheat (Triticum aestivum L.) derived from cross of heat tolerant parent WH1021 with heat sensitive parent WH711 was used. For creation of heat stress delay in sowing (four weeks) was done in late sown from timely sown. Days to heading, days to maturity, plant height along with physiological traits viz. photosynthetic rate, transpiration rate, intrinsic water use efficiency (iWUE) and normalized difference vegetative index (NDVI) were recorded in both timely and late sown conditions over two years. Results: A linkage map consisting of 22 SSR was prepared covering eleven chromosome of wheat. Using the software WinQTL cartographer version 2.5, significant genomic regions associated with heat tolerance were observed on 2A, 2D, 4A and 5A chromosomes with composite interval mapping. QTLs for photosynthetic rate were found consistently for both years on chromosome 2D. In present study, significant variation was reported for days to heading and its QTLs were identified on chromosome 2A and 2D. Interpretation: The QTLs obtained for physiological and morphological traits in wheat can be used for marker-assisted selection for heat tolerance in wheat

Evapotranspiration for irrigated agriculture using orbital satellites / Evapotranspiração para áreas irrigadas utilizando satélites orbitais

Acknowledging the importance of evapotranspiration as a mediating factor for efficient irrigation management and water balance, the objective of study is to compare the Simple Algorithm forEvapotranspiration Retrieving (SAFER) to the standard method proposed by FAO-56 for real evapotranspiration, as well as prove its value as an implement in irrigation management for the Brazilian Savanna. Data used refers to 2015's harvest of seven center pivots, located in the municipality of São Desidério in western Bahia. For the SAFER algorithm, the images used were acquired by the Landsat-8 satellite during the entire maize crop cycle. The SAFER algorithm estimation demonstrates the spatial and temporal distribution of the evapotranspiration. A maximum evapotranspiration of 5.38 mm d-1 was observed during the crop's reproductive stage. In relation to the standard method, SAFER showed a mean absolute error of 0.40 mm. Thus, concluding that the algorithm can be used to estimate the actual evapotranspiration crop as an alternative to the standard method proposed by FAO-56 for water resources management.

Reconhecendo a importância da evapotranspiração como fator mediador para uma gestão de irrigação eficiente e o balanço hídrico, o objetivo desse estudo foi comparar o Simple Algorithm for Evapotranspiration Retrieving (SAFER) ao método padrão proposto no FAO-56 para estimativa de evapotranspiração real, bem como apontar sua utilidade como ferramenta de gestão de irrigação para o Cerrado brasileiro. Utilizaram-se dados referentes à safra de 2015 de sete pivôs centrais localizados no município de São Desidério, no oeste da Bahia. Para utilizar algoritmo SAFER, adotaram-se imagens adquiridas pelo satélite Landsat-8 durante o ciclo da cultura do milho. As estimativas pelo algoritmo SAFER demonstraram a variabilidade espaço-temporal da evapotranspiração. A evapotranspiração máxima de 5,38 mm d-1 foi observada durante o estágio reprodutivo da cultura. Em relação ao método padrão, o SAFER apresentou erro médio absoluto de 0,40 mm. Dessa forma, conclui-se que o algoritmo pode ser adotado para se estimar evapotranspiração atual da cultura como alternativa ao método padrão proposto no FAO-56 na gestão de recursos hídricos.

Remote Sensing Based Land Surface Temperature Analysis in Diverse Environment of Lalgudi Block

Introduction: Land Surface Temperature (LST) is a significant climatic variable and defined as how hot the "surface" of the Earth would feel to the physical touch in a particular location. A spatial analysis of the land surface temperature with respect to different land use/cover changes is vital to evaluate the hydrological processes. Methods: The objective of this paper is to assess the spatial variation of land surface temperature derived from thermal bands of the Landsat 8 Operational Land Imager (OLI) and the Thermal Infrared Sensor (TIRS) by using split window algorithm. Place and Data: The study was conducted in Lalgudi block of Trichy District, Tamil Nadu, India. The block has diverse environment like forest area, barren land, river sand bed, water bodies, dry vegetation, cultivated areas (paddy, sugarcane, banana etc.) and settlements. Landsat 8 satellite images for four selected scenes (December 2014 & January 2015 and December 2017 & January 2018) were used to estimate the LST. Results: The spatial and temporal variation of Normalized Difference Vegetation Index (NDVI) and LST were estimated. The average NDVI values of cropped fields varied from 0.3 to 0.5 in all the scenes. The maximum value of LST ranging from 35 to 40°C was recorded in river sand bed. Subsequently, semi-urban settlements in the central part of Lalgudi block exhibited higher temperature ranging from 28 – 30°C. The LST of paddy crop and sugarcane was in the range of 23 to 25°C. The water bodies exhibited LST around 20°C. The coconut plantations, forest area and Prosopis juliflora showed LST value ranging from 24 – 29°C. This kind of block level monitoring studies helps in adopting suitable policies to overcome or minimize the problems triggered by increase in land surface temperature.

Relationship between cotton productivity and variability of NDVI obtained by landsat images / Relação entre produtividade do algodoeiro e variabilidade do NDVI obtido por imagens do landsat

The availability of satellite images has generated a large number of regional and global studies on vegetation mapping. Such studies have related the growth parameters, nutrient status, physiological responses, and water resources to the yield of agricultural crops or native vegetation. The NDVI (Normalized Difference Vegetation Index) is associated with parameters of growth and yield with readings at several moments of the crop cycle. The objective of this work was to correlate the yield and variability of the NDVI in cotton fields by analyzing Landsat satellite images acquired over nine growing seasons. The study involved the analysis of 101 cotton production fields located in West-Central Brazil. One Landsat image was used during each crop cycle, and the average yield was computed based on total fiber harvested at each field. The fiber yield ranged from 393 to 2,030 kg ha-1, and its correlation with NDVI was 0.37. The coefficient of variation (CV) had a negative correlation with yield, approximating -58.1 kg ha-1 for every one percent increment of the CV. The CV explained the yield variability over the cotton fields more accurately than the average absolute NDVI value.

Desde a disponibilização das imagens de satélites, tem-se gerado grande número de estudos regionais e globais para caracterizar a vegetação. Esses estudos têm relacionado parâmetros de crescimento, nutricionais, fisiológicos, hídricos e produtividade das culturas agrícolas ou vegetação nativa. O NDVI (Normalized Difference Vegetation Index) é associado com parâmetros de crescimento e produtividade do algodoeiro com leituras em vários momentos do ciclo. O objetivo desse trabalho foi relacionar a variabilidade do NDVI em campos de produção de algodão e a produtividade pelo uso de imagens do satélite Landsat ao longo de nove safras. O estudo foi desenvolvido com análise de 101 campos de produção localizados na região central do Brasil. Foi utilizada uma imagem durante o ciclo da cultura e a produtividade média obtida. A produtividade de fibra variou de 393 a 2.030 kg ha-1 e a correlação com NDVI foi de 0,37. O coeficiente de variação teve correlação negativa, com queda na produtividade em -58,1 kg ha-1 ao aumentar um ponto percentual. O coeficiente de variação explicou melhor a variabilidade da produtividade dos talhões que o NDVI médio.

Natural regeneration in anthropogenic environments due to agricultural use in the cerrado, Uberaba, MG, Brazil / Regeneração natural em ambientes antropizados por usos agrícolas no cerrado, Uberaba, MG, Brasil

Evidence of environmental impact on the Cerrado is characterised by the presence of large homogeneous pastures and agricultural areas, with the presence of very fragmented and scattered forest fragments. When these areas are abandoned due to low productivity, natural regeneration begins, which is influenced by environmental factors. The goal of the present study was to evaluate the forest cover temporal dynamics in anthropogenic areas and the influence of climate on natural regeneration in the Cerrado. The study site was an anthropogenic area that has been protected against the entrance of domestic animals and agriculture since 2002. Environments were identified, and natural regeneration dynamics were analysed by the use of vegetation indices calculated from satellite images. Statistical analysis Non-parametric Mann-Kendall was used to check the trend of the rain and the Normalized Difference Vegetation Index, multivariate analysis to verify the correlations and groups between the years of occurrence of El Niño and La Niña and the values of Normalized Difference Index. Natural regeneration in the Cerrado increased over time and was positively correlated with rainfall incidence. The process of recovery of degraded areas by natural regeneration technique proved efficient in the Cerrado, however, natural regeneration is negatively influenced by the weather phenomenon El Niño.

No Cerrado a evidencia dos impactos ambientais são as grandes áreas homogêneas com pastagens e agricultura, com a presença de fragmentos florestais muito fragmentados e esparsos. Quando as áreas são abandonadas devido à baixa produtividade, inicia-se o processo de regeneração natural, com influência dos fatores ambientais. Assim, o objetivo desse estudo foi avaliar a dinâmica temporal da cobertura florestal em áreas antropizadas e a influência das condições climáticas no processo de regeneração natural no Cerrado. Para tanto, foi utilizada uma área antropizada protegida contra a entrada de animais domésticos e explorações agrícolas desde 2002. A identificação dos ambientes e a dinâmica do processo de regeneração natural foram obtidas por meio de imagens orbitais com o cálculo do índice de vegetação. A análise estatística não-paramétrica de Mann-Kendall foi utilizada para verificar a tendência da chuva e do Normalized Difference Vegetation Index, a análise multivariada para verificar as correlações e agrupamentos entre os anos de ocorrência de El Niño e La Niña e os valores do Normalized Difference Index. A dinâmica do processo de regeneração natural no Cerrado apresentou um padrão crescente em função do tempo e uma correlação positiva com a incidência de chuvas. O processo de recuperação de áreas degradadas pela técnica de regeneração natural mostrou se eficiente no Cerrado, no entanto, a regeneração natural é influenciada negativamente pelo fenômeno climático El Niño.

Sufficiency index for defining nitrogen recommendation in brachiaria grass pasture / Índice de suficiência para a definição de recomendação de nitrogênio em pastagem de capim braquiária

In addition to be absorbed by plants, nitrogen (N) applied in the soil is subject to loss by leaching, volatilization and microorganism immobilization. The spectral characteristics of plants have been used for defining the N fertilizer rate. However, it has been a challenge to translate the sensor readings into the N rate. Thus, the aim of the present study was to evaluate three spectral variables to recommend variable rate N fertilization in Brachiaria decumbens using the Nitrogen Sufficiency Index (NSI). The five treatments consisted of a control plot (without nitrogen application), a reference plot with a fixed N rate of 150 kg ha-1 and three different spectral readings for applying N at variable rates. In the variable rate plots were initially applied a N rate equal to 50% of that in the reference plot, and the following rates were defined based on NSI. The three spectral variables were: a portable chlorophyll meter readings, Visible Atmospherically Resistant Index (VARIRedEdge) and the ratio between Modified Chlorophyll Absorption Ratio Index and Optimized Soil Adjusted Vegetation Index (MCARI/OSAVI). The experiment was conducted in randomized block design with five replicates during three plant harvesting. The forage was harvested when the plant height was 25 cm in the reference plot. The variable rate treatments presented better nitrogen use efficiency than the fixed rate treatment. The portable chlorophyll meter was more suitable than the used vegetation indices to recommend variable N rate fertilization since their plots produced the same dry biomass matter as in the fixed rate plot with less amount of fertilizer applied.

Além de ser absorvido pelas plantas, o nitrogênio (N) aplicado no solo está sujeito à perda por lixiviação, volatilização e imobilização pelos microrganismos. As características espectrais das plantas têm sido usadas para definir a taxa de aplicação de fertilizante nitrogenado. No entanto, tem sido um desafio transformar as leituras dos sensores em taxas de N. Assim, o objetivo do presente estudo foi avaliar três variáveis espectrais para recomendar adubação nitrogenada a taxa variável em Brachiaria decumbens, usando o Índice de Suficiência de Nitrogênio (NSI). Os cinco tratamentos consistiram de uma testemunha (sem aplicação de N), de uma parcela de referência com uma taxa de N fixa de 150 kg ha-1 e três leituras espectrais diferentes para a aplicação de N a taxas variáveis. Na taxa variável, as parcelas receberam inicialmente uma taxa de N igual a 50% da parcela de referência, e as seguintes taxas foram definidas com base no NSI. As três variáveis espectrais foram: as leituras do medidor portátil de clorofila (SPAD), Visible Atmospherically Resistant Index (VARIRedEdge) e a razão entre Modified Chlorophyll Absorption Ratio Index e Optimized Soil Adjusted Vegetation Index (MCARI/OSAVI). O experimento foi conduzido em delineamento em blocos casualizados, com cinco repetições durante três colheitas da planta. A forragem foi colhida quando a altura da planta atingiu 25 cm na parcela de referência. Os tratamentos a taxa variável apresentaram melhor eficiência de uso de N do que o tratamento a taxa fixa. O medidor portátil de clorofila foi mais adequado que os índices de vegetação usados para recomendar a adubação nitrogenada à taxa variada uma vez que suas parcelas produziram a mesma massa seca que na parcela a taxa fixa com uma menor quantidade de N aplicado.

Comparação de áreas de soja (Glycinemax (L) Merr. ) obtidas por meio da interpretação de imagens TM/Landsat e MODIS/Terra no município de Maracaju (MS) / Comparison of areas of soybean (Glycine max (L) Merr. ) obtained through the interpretation of tm/landsat and modis/terra images in the municipality of Maracaju (MS)

A cultura da soja possui características favoráveis para sua identificação e mapeamento por meio de interpretação de imagens de sensores remotos a bordo de satélites.O presente trabalho teve como objetivo comparar os resultados de mapeamento dessa cultura, por meio da interpretação de imagens TM/Landsat-5 e MODIS/Terra para o ano safra 2010/11. O trabalho foi realizado para o município de Maracaju, Mato Grosso do Sul, maior produtor de soja do Estado. Foram adquiridas oito imagens MODIS/Terra no ano de 2010 e quatro em 2011 e uma do TM/Landsat-5 do ano de 2011, compreendendo o período de cultivo da soja na região. De posse das imagens e dos processamentos foram gerados mapas temáticos de áreas de soja, das quais segue: componentes principais de imagem monotemporal TM, monotemporal MODIS com seus respectivos NDVI´s e EVI´s, por meio do classificador supervisionado MaxVer; além disso foi calculado o índice CEI, que no processo de fatiamento de pixels foram obtidas as áreas de soja. As classificações utilizando bandas do TM/Landasat-5 apresentaram excelentes estimativas de áreas de soja indicadas pelas métricas de validação Kappa e exatidão global. No método do índice CEI, neste caso, apresentou inferioridade perante as demais estimativas obtidas, apenas apresentando-se superior a estimativa de área obtida pela imagem monotemporal NDVI/MODIS.

The soybean has favorable characteristics for its identification and mapping through interpretation of remote sensing images. This paper aims compare the mapping results of this culture by interpretation of TM/Landsat-5 and MODIS/Terra images for the crop-year 2010/11. The study area was the town of Maracaju, Mato Grosso do Sul, Brazil, the larger producer of soybeans in the state. Eight MODIS/Terra images were acquired in 2010, four in 2011 and one TM/Landsat-5 in 2011, comprising the period from soybean cultivation in the region. With ' thematic maps of soybean areas, of which follows: principal components of mono temporal TM image with their respective MODIS NDVI's and EVI's, through the Max Ver classifier; addition we calculated the CEI index, which in the process of slicing the pixel areas were obtained from soybeans. The classifications using TM/Landasat-5 bands showed excellent estimates of soybean areas, indicated by the metrics validation Kappa and overall accuracy. In the method CEI index presented inferiority before the other estimates are they only over area estimation obtained by the mono temporal NDVI/MODIS image.

Identification of snail habitats in the Poyang Lake region, based on the application of indices on joint normalized difference vegetation and water / 中华流行病学杂志

Objective With Landsat TM remote sensing images,snail habitats in Poyang Lake region were identified,using two indices:the modified normalized difference water index (MNDWI) and the normalized difference vegetation index (NDVI).Methods Two Remote sensing images of both wet and drought seasons in Poyang Lake region were obtained.MNDWI and NDVI were extracted from the images respectively,to present the regions of “water in summer and land in winter” and the coverage of vegetation.By overlaying those two regions,the areas of potential snail habitats were drawn.Finally,sensitivities and specificities of the recommended methods were assessed and compared to that of the traditional methods for the sake of extracting the areas of snail habitats.Results The threshold values of MNDWI for the wet and drought seasons were 0.34 and 0.58,respectively and the threshold value for NDVI of the drought season was 0.02.Sensitivity and specificity of our method were 95％ and 100％,respectively,higher than the conventional approach (se.=75％,sp.=100％ ).Conclusion Joint application of MNDWI and NDVI seemed a better method to detect the snail habitats and could be used for the quantitative and automatic surveillance program on snails.

Snail habitats detection in the marshland of Eastern Dongting Lake Area, based on China-Brazil Earth Resources Satellite-02B CCD data / 中华流行病学杂志

Objective To detect the snail habitats from the marshland of Eastern Dongting Lake Area, using the Remote Sensing (RS) and Geographic Information System (GIS) technology based on the China-Brazil Earth Resources Satellite-02B (CBERS-02B) CCD images. Methods According to the two typical traits of snail habitats in marshland including "water in summer and land in winter" and "no grass, no snails" , the "water in summer and land in winter" region and the vegetation coverage region were calculated by RS image processing respectively. The two regions mentioned above were then overlapped to confirm the snail habitats through comparing with the data from field survey under spatial overlapping of Arcgis as the last step. Results In Eastern Dongting Lake area, the "water in summer and land in winter" region and vegetation coverage region were predicted based on the formula normalized difference water index (NDWI) >0.01 and normalized difference vegetation index (NDVI) >0.36, respectively. The snail habitat was determined by theme overlay of the two regions said above.The agreement rate between the prediction and the geospatial data of field survey was 93.55% , which demonstrated the final results were credible and reliable. Conclusion CBERS-02B image could be used to detect the snail habitats and to monitor the changes of them, so as to find out the characteristics of distribution and the trends of diffusion. The snail index (discriminant 1 and 2) seemed to be suitable for the detection of snail habitats in the marshland of Lake area and used for the programs of snail control.

Caracterização espectral multitemporal dos cereais de estação fria em imagens de satélite com média resolução espacial / Multitemporal spectral characterization of cool season cereals in satellite images with moderate spatial resolution

A fim de avaliar os padrões de resposta de áreas cultivadas com cereais de estação fria destinados para pastagens e para produção de grãos em imagens de satélite, foram analisados perfis temporais de índice de vegetação por diferença normalizada (NDVI), adquiridos em 29 áreas cultivadas com trigo e azevém anual, nos Estados do Rio Grande do Sul e Paraná. Para cada área foi informada a espécie cultivada (trigo ou azevém anual) e a coordenada do ponto central da área adquirido por meio do Global Positioning System (GPS). Foram usadas as imagens do sensor MODIS (Moderate Resolution Imaging Spectroradiometer), com resolução espacial de 250 metros, sobre cada área monitorada, de onde os valores de NDVI foram extraídos. Os perfis temporais de NDVI mostraram que os cultivos de produção de grãos têm um comportamento espectral típico de cultivos agrícolas, enquanto que, nas áreas cultivadas para a produção de pastagem, não foi observado esse mesmo padrão. As diferenças nos padrões temporais observadas se devem a modificações que o pastoreio impõe na fenologia e na morfologia dessas plantas.

In order to evaluate the satellite image patterns between such cool season cereals cultivated areas intended for grazing or grain production, Normalized Difference Vegetation Index (NDVI) temporal profiles were analyzed. This data was acquired from twenty nine wheat and annual ryegrass cultivated areas in the states of Rio Grande do Sul and Paraná. For each area, the cultivated species (wheat or ryegrass), as well as the respective central point coordinates, acquired via Global Positioning System (GPS) was informed. NDVI values were extracted over each monitored area from MODIS (Moderate Resolution Imaging Spectroradiometer) sensor images, with spatial resolution of 250 meters. The NDVI temporal profiles showed that grain production areas have a typical agricultural field spectral pattern. The same pattern was not observed for the grazing pasture areas. The differences observed in these temporal patterns are defined by the changes that grazing has imposed on the phenology and morphology of these plants.