MODIS NDVI, EVI and NDWI time series for cotton phenological characterization

O desenvolvimento e a competitividade do setor agrícola brasileiro estão atrelados aos avanços tecnológicos e eficiência na alocação dos recursos. A utilização de dados de sensores orbitais destaca-se como ferramenta para o acompanhamento dos cultivos, a avaliação dos sistemas de produção e a previsão de safra. Esse potencial dos sensores orbitais foi impulsionado pelos avanços da resolução temporal, destacando-se o sensor Moderate Imaging Spectroradiometer (MODIS). O presente trabalho teve como objetivo caracterizar os estádios fenológicos do algodão no Cerrado utilizando séries temporais de NDVI, EVI e NDWI do sensor MODIS. A utilização efetiva dessas séries temporais mostra-se dependente do tratamento dos ruídos. O emprego conjunto do filtro de mediana e da transformação inversa da Fração Mínima de Ruído (FMR) apresentou-se como eficiente alternativa para o tratamento dos ruídos. Os comportamentos médios anuais de NDVI, EVI e NDWI evidenciam uma variação sazonal que caracterizam os estágios fenológicos da cultura do algodão. ____________________________________________________________________________________ ABSTRACTThe development and competitiveness of the Brazilian agricultural sector are coupled to technological advances and efficiency in resource allocation. The use of orbital sensor data stands as an important tool for the crops monitoring, production system evaluation and forecasting. This potential was driven by the improving of the temporal resolution specially the Moderate Imaging Spectroradiometer (MODIS). This work aimed to characterize the phenological stages of cotton in the Cerrado biome using MODIS NDVI, EVI and NDWI time series. However, the effective utilization of this time series is dependent of the noise reduction. The employment of the median filter and inverse transformation of Minimum Noise Fraction (MNF) proved to be efficient as noise reduction procedures. The annual average temporal behavior of NDVI, EVI and NDWI show a seasonal variation that characterizes the phenological stages of the cotton crops. Beyond this phenological characterization, the procedures presented can support the regional production arrangements, energetic fluxes monitoring and evaluation of production system efficiency

Modis time series applied to crop succession of soybean (Glycine max (L.) Merril) and maize (Zea mays L.) in no-tillage system

Os sensores orbitais com alta resolução temporal proporcionam identificar as etapas fenológicas dos cultivos agrícolas. O presente artigo teve como objetivo analisar séries temporais do sensor Moderate Imaging Spectroradiometer (MODIS) para a descrição das sucessões soja-milho e milho-soja em sistema de plantio direto. As imagens utilizadas são os produtos de reflectância de superfície composição de oito dias (MOD09), contendo sete bandassobre um período de 12 anos (200-2011). A metodologia adotada pode ser subdividida nas seguintes etapas: (a) eliminação dos ruídos das séries temporais a partir da combinação do filtro de mediana com a Fração Mínima de Ruido (FMR), (c) elaboração dos índices de vegetação Normalized Difference Vegetation Index (NDVI); Enhanced Vegetation Index (EVI) e Normalized Difference Water Index (NDWI); (c) análise estatística com o propósito de identificar a correspondência das séries temporais com as fases de sucessão de culturas soja e milho. Os dados temporais NDVI, EVI, e NDWI apresentam respostas sazonais para o cultivo de sucessão de milho-soja e soja-milho, mostrando-se consistentes com a fenologia das culturas. Os perfis temporais tratados evidenciaram os comportamentos ao longo do tempo, sendo que a soja como primeira cultura apresentou maiores valores para todos os índices avaliados. A soja apresentou em média um ciclo de 143 dias, com início da semeadura em 23 de outubro. O ciclo produtivo médio do milho como cultura principal foi 127 dias, com início em 08 de novembro. _________________________________________________________________________________ ABSTRACTThe orbital sensors with high temporal resolution allowed improvements in the phonological stages characterization. This paper aimed to analyze time series from Moderate Imaging Spectroradiometer (MODIS) sensor for the soybeancorn and corn-soybean succession in no-tillage system. The images used are the MODIS surface reflectance 8-day composite products (MOD09), containing seven-band over a 12-year period (2000-2011). The methodology can be subdivided into the following steps: (a) noise elimination of time series combining the median filter with a Minimum Noise Fraction (MNF); (c) application of vegetation indices: Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI) and Normalized Difference Water Index (NDWI); and (c) statistical analysis in order to identify the correspondence of the time series with the phases of crop rotation soybeans and corn. EVI, NDVI and NDWI temporal profiles show seasonal responses to crop succession of corn-soybeans and soybeans- corn. Temporal signatures were consistent with the general phenological characteristics. The smoothed temporal profiles evidenced the behavior through the time and that the soybean as first crop showed the highest values for all vegetation indices evaluated. The soybean had an average 143-days cycle, beginning in October 23th. The average productive cycles of the maize as main crop were 127-days, starting in November 8th

Hydraulic properties of the diagnostic horizon of Latosols of a regional toposequence across the Brazilian Central Plateau.

International audienceThe Brazilian Central Plateau covers about 40% of the Cerrados Biome and represents 24% of the Brazilian territory. The Latosols that correspond to about 40 % of the surface area of the Central Plateau are characterized by a poor horizonation, a weak macrostructure and a strong development of the fine granular structure composed of sub-rounded microaggregates 50 to 300 µm in size. In this study, we analyzed the hydraulic properties of a set of Latosols varying according to their clay content and mineralogy with respect to their location along a regional topossequence across the Brazilian Central Plateau. Ten Latosols (L) were selected on the South American Surface (L1 to L4) and Velhas Surface (L5 to L10) and we studied the properties of their diagnostic horizon (Bw). We measured their bulk density and particle density, and the soil-water retention properties at 1, 6, 10, 33, 300, and 1500 kPa by using the centrifugation method. We also determined the saturated hydraulic conductivity in the field using the Guelph permeameter procedure. Results showed that the total pore volume (Vp) ranged from 0.460 to 0.819 cm3 g-1 and 58.2 % of the variance was explained for by the clay content. According to Balbino et al. (2002), Vp was divided into a volume of intra-microaggregates pores (Vintra) and inter-microaggregates pores (Vinter). Results showed that Vintra ranged from 0.090 to 0.234 cm3 g-1 and Vinter from 0.305 to 0.585 cm3 g-1. Results showed also that Vp explained a proportion of the variance of the water retained that decreased with the water potential. On the other hand, the clay content explained a proportion of that variance that increases when the water potential decreased. The great proportion of variance (90.7 %) explained for by the clay content alone at 1500 kPa showed that there is little variability that can be attributed to clay mineralogy variation. The saturated hydraulic conductivity (Ks) was related to an effective porosity (Φe) defined as the volume proportion of pore with equivalent diameter > 300 µm. Finally, our results showed that water retention properties and saturated hydraulic conductivity varied mainly according to the clay content and development of large pores without any close link with the mineralogy of the clay fraction

Identificação das assinaturas temporais NDVI das principais fisionomias da região do Ecomuseu do cerrado

A Savana brasileira, conhecida como Cerrado, é o principal tipo de vegetação no Brasil Central, cobrindo aproximadamente 23% do território nacional. É formado por um mosaico de coberturas como campestres, arbustiva e florestal, e apresenta uma fenologia típica, resultante da variação pluviométrica e alta dependência geobotânica nesta região. Imagens adquiridas na mesma área em tempos diferentes representam uma valiosa fonte de informação para o monitoramento regular da superfície terrestre, permitindo descrever a evolução da cobertura da terra, fenologia da vegetação entre outros. Desta forma, o objetivo deste trabalho é identificar as assinaturas temporais do cerrado na região do Ecomuseu do Cerrado através do processamento de série temporal de imagens MODIS. A metodologia pode ser subdivida nas seguintes etapas: (a) elaboração do cubo das imagens de NDVI, onde o perfil “Z” corresponde à assinatura temporal do NDVI, (b) eliminação do ruído utilizando a transformação Mininum Noise Fraction (MNF), e (c) análise da assinatura temporal do NDVI. O estudo concluiu que o NDVI é útil na diferenciação entre os tipos de vegetação do Cerrado. A formação florestal apresentou os maiores valores de NDVI entre os perfis temporais, além da menor variação entre as estações. ________________________________________________________________________________________ ABSTRACTThe Brazilian Savanna, known as Cerrado, is the main vegetation type in Central Brazil, covering approximately 23% of the national territory. The Cerrado is formed by a mosaic of land cover types such as grassland, shrubland and woodland, and shows a typical phenology, due to the pluviometric variation and high geobotanical dependence. Images acquired on the same area at different times represent a valuable source of information for a regular monitoring of the earth’s surface that enables to describe the land-cover evolution, vegetation phenology, among others. Thus, the scope of the paper is to identify temporal signatures of the Cerrado in the Ecomuseu do Cerrado region by image processing of MODIS time series. The adopted methodology may be subdivided into the following steps: (a) elaboration of the NDVI images cube, where the z profile corresponding to NDVI temporal signature, (b) noise elimination using the Minimum Noise Fraction (MNF), and (c) NDVI temporal signature analysis. The study concluded that the NDVI series is useful in differentiation among Cerrado vegetation types. The forest formation showed the higher NDVI values among the temporal profiles and lower variation between seasons

Carbono e nitrogênio do solo sob diferentes usos e posições na paisagem no Brasil central

In Central Brazil, plateaus, the most common geomorphologic form, have been undergoing intense conversion from native vegetation to pasture and agriculture in recent decades. We used carbon stable isotope ratios (δ13C) and nitrogen stable isotope ratios (δ15N) to assess possible changes in soil organic matter dynamics under such land use modifications. This study aimed to evaluate the differences in soil δ13C and δ15N and C and N stocks between native vegetation and agricultural or pasture areas in different locations of a plateau in the savannas of Central Brazil. We sampled soil up to 100 cm depth in pasture areas in the summit of the plateau and no-tillage and conventional tillage on the border of a plateau, as well as soils under native vegetation in both landscape locations. Both soil δ13C and δ15N, and C and N stocks showed no differences between land uses. The different relationships between δ15N and C/N ratio at different locations indicated distinct behavior of the soil organic matter between the summit and border of the plateau. Therefore, in addition to land-use, landscape location contributes to both δ13C and δ15N, and C and N stocks in the soil of the plateau.No Brasil Central, os planaltos são a forma geomorfológica mais comum e vêm sofrendo intensa conversão de vegetação nativa em pastagem e agricultura nas últimas décadas. Os isótopos estáveisde carbono (δ13C) e de nitrogênio (δ15N) foram usados neste estudo para acessar possíveis mudanças na dinâmica da matéria orgânica no solo nestas áreas convertidas. Este estudo teve como objetivo avaliar as diferenças no δ13C e no δ15N e nos estoques C e N do solo entre a vegetação nativa e áreas agrícolas ou de pastagem em diferentes posições de um planalto nas savanas do Brasil Central. Foram coletadas amostras de solo até 100 cm de profundidade em áreas de pastagem no topo e plantio direto e convencional na borda do planalto, bem como solos sob vegetação nativa em ambas as posições. O δ13C, o δ15N e os estoques de C e N não mostraram diferenças entre os usos da terra. As diferentes relações entre δ15N e a razão C/N em cada posição indicam um comportamento distinto da matéria orgânica do solo entre o topo e a borda do planalto. Portanto, além do uso da terra, a posição da paisagem contribui para os valores de δ13C e δ15N e os estoques de C e N no solo desse planalto

Denoising and caracterization of cerrado physiognomies using MODIS times series

O Cerrado é formado por um mosaico de fisionomias campestres, savânicas e florestais que possuem um típico ciclo fenológico. Nesse contexto, os dados do MODIS fornecem medidas diárias que permitem monitorar a sazonal fenologia da vegetação. O objetivo deste trabalho foi caracterizar formações savânicas, formações florestais e áreas de cerrado convertido pela ação antrópica, utilizando séries temporais de NDVI e EVI do sensor MODIS, após a suavização de ruídos. A metodologia adotada pode ser subdividida nos seguintes passos: (a) confecção do cubo temporal com NDVI e EVI, onde o perfil em z corresponde à assinatura temporal, (b) tratamento do ruído e (c) detecção das assinaturas temporais. A Transformação pela Fração Mínima de Ruído (MNF) foi aplicada para suavizar ruídos contidos nas séries temporais. Os resultados indicaram que os valores de NDVI foram maiores que os valores de EVI e existiu relação com as estações do ano. As formações florestais foram as que apresentaram maiores valores de NDVI e EVI, possuindo ainda as menores variações entre as estações. As áreas convertidas apresentaram os menores valores dos dois índices, tendo grande queda em seus valores no início da estação seca, provavelmente por se tratar do período de colheita. O estudo concluiu que as séries temporais NDVI e EVI são úteis na diferenciação dos tipos de vegetação.Cerrado is formed by a mosaic of grassland, shrubland and woodland physiognomies with a typical phenological cycle. Thus, MODIS data provide daily measurements which allows to monitor the seasonal phenology of the vegetation. The objective of this work was to characterize savanna formations, forest formations and cerrado areas converted by anthropic actions, by using temporal series of MODIS NDVI and EVI after noise reduction. The adopted methodology should be divided into the following steps: (a) elaboration of the temporal cube with NDVI and EVI, in which the z profile corresponds to temporal signature, (b) noise elimination, (c) detection of temporal signature. The Minimum Noise Fraction Transformation (MNF) method was applied to reduce noise in temporal signature. The results showed that the NDVI values were higher than the EVI; and there was a relationship with the seasons of the year. The forest formations presented the highest values of NDVI and EVI, showing the lowest variations among the seasons. The converted areas of Cerrado presented the lowest values in both indices, and their values decreased in the beginning of the dry season, probably because it was the harvesting season. The study concluded that the NDVI and EVI temporal series are useful in differentiation among vegetation types

Relação entre uso e ocupação do solo e os aspectos geomorfológicos no município de Águas Lindas de Goiás

Este trabalho teve o objetivo de avaliar o uso e cobertura do solo e sua relação com os aspectos geomorfológicos no município de Águas Lindas de Goiás, utilizando imagens CBERS e aplicando o método de árvore de decisão. Além disso, mostrar como vem sendo a ocupação urbana através de parâmetros morfométricos usando SRTM. Em 2006, aproximadamente 40% de sua área havia sido convertida em áreas agrícolas, pastagem e áreas urbanas. A estimativa da taxa de conversão das áreas naturais em usos antrópicos foi 0,8% ano no período estudado. Observou-se que a ocupação urbana ocorre principalmente na unidade geomorfológica da Chapada, cobrindo mais de 50% de sua superfície. Pode-se inferir que a expansão da área urbana está ocorrendo para o lado leste, onde ocorre uma continuidade do relevo com uma feição mais aplainada e com declividades mais amenas.This work aimed to evaluate the land use and land cover related to geomorphology of Águas Lindas de Goiás by using CBERS images and decision tree method. In addition to show how the city is growing according to morphometric parameters by using SRTM. By the year 2006, approximately 40% of the municipality area was converted into agriculture and pasture area, and urban area. The conversion index of the natural area in antropic use was 0.8% per year in the period of study. It was observed that the urban area occurs primarily in the Plateau unity covering more than 50% of the unity surface. It is said that the expansion of the urban area occurs to east, due to continuity of the relief with plainer feature small slope

Dissolution of silicate minerals and nutrient availability for corn grown successively

O objetivo deste trabalho foi avaliar a disponibilidade de nutrientes para milho (Zea mays) cultivado sucessivamente em amostras das rochas puras e moídas biotita xisto e biotita sienito. Os pós das rochas foram submetidos à caracterização química, física e mineralógica, e a disponibilidade dos elementos liberados para as plantas foi determinada. Os materiais de planta e rocha foram avaliados no final de sete ciclos sucessivos de cultivo. A biotita xisto e a biotita sienito forneceram nutrientes – como K, Ca, Mg, Fe e Mn – para as plantas de milho. Os nutrientes acumulados no tecido das plantas vieram de minerais contendo Fe e Mn oxidáveis em sua estrutura, tais como biotita, chlorita e clinopiroxênio. A dissolução congruente de algumas partículas finas dos minerais, solubiliza elementos que podem, então, ser disponibilizados para as plantas.The objective of this work was to evaluate the nutrient availability for corn (Zea mays) grown successively in pure and ground biotite schist and biotite syenite rock samples. The rock powders were subjected to chemical, physical, and mineralogical characterization, and the availability of the elements released to the plants was determined. Plant and rock materials were evaluated at the end of seven successive growth cycles. Biotite schist and biotite syenite provided nutrients – as K, Ca, Mg, Fe, and Mn – to the corn plants. The nutrients accumulated in plant tissues came mostly from minerals containing oxidizable Fe and Mn in their structure, such as biotite, chlorite, and clinopyroxene. The congruent dissolution of some of the fine particles of these minerals, solubilize elements, which may, then, be available to the plants

Modelling of bulk density as related to aggregate size distribution in clayey Ferralsols

Among microaggregated soils, there are Ferralsols that show little or no distinct horizonation. Their macrostructure is weak to moderate and they have typically a strong microstructure. In most Brazilian clayey Ferralsols, physical properties are closely related to the development of microstructure that consists of subrounded microaggregates 50 to 500 µm in diameter

Mass Proportion of Microaggregates and Bulk Density in a Brazilian Clayey Oxisol.

The physical properties of Brazilian Oxisols are closely related to the development of their microstructure, which typically consists of stable microaggregates smaller than 1 mm. There is no model available to predict changes in microstructure in Oxisols. The objective of this work was to relate the proportion of microaggregates to the bulk density (Db) in the soil studied. Five sites of a typic Haplustox under native vegetation (two sites) and pasture (three sites) were sampled. Soil bulk density, sand, silt, and clay content and aggregate size distribution were measured from the surface to 1.6 m deep in increments of 0.1 m. Thin sections were prepared from undisturbed samples collected in duplicate from 0-0.1 m, 0.3-0.4 m, 0.8-0.9 m and 1.5-1.6 m depth, and backscattered electron scanning images (BESI) were generated. Clay content ranged from 672 to 798 g kg-1 and bulk density between 0.87 and 1.18 g cm-3 among the 80 samples studied. Db was poorly correlated with clay content (R² = 0.358) and at any depth was not significantly smaller under native vegetation than under pasture. Visual assessment of BESI revealed that soil material corresponded to either microaggregates (< 0.1 mm) in loose arrangement or to much larger aggregates. Quantification of BESI from the deepest sampling depth of all soils showed that 96.2 and 95.7 % of microaggregates were < 0.8 mm with 73.2 and 95.7 % between 0.1 and 0.5 mm under native vegetation and pasture, respectively. The mass proportion of microaggregates can be estimated using the < 0.84 mm soil material that is obtained by dry sieving (&<0.84). Finally, our results showed that &<0.84 varied with Db. Linear regression coefficients were calculated for the relationship between &<0.84 and the reciprocal of bulk density (1/ Db) (&<0.84 = 1.97 (1/ Db) – 1.52, R² = 0.82), assuming no interaction between microaggregates and macroaggregates, the porosity of these two structural types was estimated as 0.71 and 0.51, respectively