Time filter

Source Type

Marin F.,Embrapa Informatica Agropecuaria | Nassif D.S.P.,University of Sao Paulo
Revista Brasileira de Engenharia Agricola e Ambiental | Year: 2013

Based on literature, this paper examines qualitativelly a future scenario for the sugarcane in Brazil. It was done considering the expanding trend of the crop observed over the last decade, the current sector conjuncture, and the down scaled climate change projections for this century. The focus was to associate the scientific findings on the physiology of sugarcane and their responses to the rise in atmospheric CO2 concentration and the water use efficiency with socio-economic prospects for the sugarcane industry in Brazil. Probable effects on weeds, diseases and pest of sugarcane crop were also analysed. Available literature indicates that sugarcane crop would likely show a positive response to probably scenarios of climate change in Brazil due both to direct response of photosynthesis in view of increase of carbon dioxide and the higher water use efficiency. However, it is likely that the crop management may require adaptation to the future climate, since weeds and diseases could be favored under the future climate.

Marin F.R.,Embrapa Informatica Agropecuaria | de Carvalho G.L.,University of Sao Paulo
Pesquisa Agropecuaria Brasileira | Year: 2012

The objective of this work was to assess the spatial and temporal variability of sugarcane yield efficiency and yield gap in the state of São Paulo, Brazil, throughout 16 growing seasons, considering climate and soil as main effects, and socioeconomic factors as complementary. An empirical model was used to assess potential and attainable yields, using climate data series from 37 weather stations. Soil effects were analyzed using the concept of production environments associated with a soil aptitude map for sugarcane. Crop yield efficiency increased from 0.42 to 0.58 in the analyzed period (1990/1991 to 2005/2006 crop seasons), and yield gap consequently decreased from 58 to 42%. Climatic factors explained 43% of the variability of sugarcane yield efficiency, in the following order of importance: solar radiation, water deficit, maximum air temperature, precipitation, and minimum air temperature. Soil explained 15% of the variability, considering the average of all seasons. There was a change in the correlation pattern of climate and soil with yield efficiency after the 2001/2002 season, probably due to the crop expansion to the west of the state during the subsequent period. Socioeconomic, biotic and crop management factors together explain 42% of sugarcane yield efficiency in the state of São Paulo.

Brown J.C.,University of Kansas | Kastens J.H.,University of Kansas | Coutinho A.C.,Embrapa Informatica Agropecuaria | Victoria D.D.C.,Embrapa Monitoramento por Satelite | Bishop C.R.,University of Kansas
Remote Sensing of Environment | Year: 2013

MODIS 250-m NDVI and EVI datasets are now regularly used to classify regional-scale agricultural land-use practices in many different regions of the globe, especially in the state of Mato Grosso, Brazil, where rapid land-use change due to agricultural development has attracted considerable interest from researchers and policy makers. Variation exists in which MODIS datasets are used, how they are processed for analysis, and what ground reference data are used. Moreover, various land-use/land-cover classes are ultimately resolved, and as yet, crop-specific classifications (e.g. soy-corn vs. soy-cotton double crop) have not been reported in the literature, favoring instead generalized classes such as single vs. double crop. The objective of this study is to present a rigorous multiyear evaluation of the applicability of time-series MODIS 250-m VI data for crop classification in Mato Grosso, Brazil. This study shows progress toward more refined crop-specific classification, but some grouping of crop classes remains necessary. It employs a farm field polygon-based ground reference dataset that is unprecedented in spatial and temporal coverage for the state, consisting of 2003 annual field site samples representing 415 unique field sites and five crop years (2005-2009). This allows for creation of a dataset containing "best-case" or "pure" pixels, which we used to test class separability in a multiyear cross validation framework applied to boosted decision tree classifiers trained on MODIS data subjected to different pre-processing treatments. Reflecting the agricultural landscape of Mato Grosso as a whole, cropping practices represented in the ground reference dataset largely involved soybeans, and soy-based classes (primarily double crop 'soy-commercial' and single crop 'soy-cover') dominated the analysis along with cotton and pasture. With respect to the MODIS data treatments, the best results were obtained using date-of-acquisition interpolation of the 16-day composite VI time series and outlier point screening, for which five-year out-of-sample accuracies were consistently near or above 80% and Kappa values were above 0.60. It is evident that while much additional research is required to fully and reliably differentiate more specific crop classes, particular groupings of cropping strategies are separable and useful for a number of applications, including studies of agricultural intensification and extensification in this region of the world. © 2012.

Esquerdo J.C.D.M.,Embrapa Informatica Agropecuaria | Esquerdo J.C.D.M.,University of Campinas | Zullo J.,University of Campinas | Antunes J.F.G.,Embrapa Informatica Agropecuaria
International Journal of Remote Sensing | Year: 2011

In Brazil there is a need for less subjective, more efficient and less expensive methodologies for crop yield forecast. Owing to the continental dimensions of the country, orbital images have been used to estimate the productive potential of crops. In this study, NDVI (Normalized Difference Vegetation Index) time-series, derived from AVHRR/NOAA (Advanced Very High Resolution Radiometer/National Oceanic and Atmospheric Administration) imagery were used for the soybean crop monitoring in a large production region in Brazil in the 2002/2003 and 2003/2004 cropping seasons. NDVI temporal profiles describing the biomass condition of crops throughout the phenological stages were generated in 18 municipalities. Quantitative parameters were measured from the temporal profiles, based on the full time or partial phenological cycle. Linear regressions between the quantitative parameters and the municipal average yields in both seasons have shown that the most significant correlations occurred when the full time period was considered. When considering periods prior to harvest, the correlations showed a tendency to decline. The NDVI monitoring during these two cropping seasons, which presented different weather conditions, could explain a major part of the soybean yield variability at the municipal level. Results showed the potential of the NDVI time-series analysis in generating parameters to be employed by agrometeorological-spectral models for soybean yield estimations. The automatic system for temporal profiles generation developed in this study sped up the analysis and can be used for further studies at a regional scale. © 2011 2011 Taylor & Francis.

Porto de Carvalho J.R.,Embrapa Informatica Agropecuaria | Assad E.D.,Embrapa Informatica Agropecuaria | Pinto H.S.,University of Campinas
Atmospheric Research | Year: 2011

The purpose of this study is to evaluate the accuracy of the estimation the monthly mean temperature simulated by the PRECIS model-scenarios A2 and B2 of the IPCC-for Brazilian regions and to develop a Kalman filter to correct the systematic errors of the model for the months of January to June 2010. With a regionalized model, PRECIS aims to reproduce the main features of the climate in complex terrains. The temperature estimates for January to June 2010 are based on linear regression of PRECIS simulations in each pixel of the domain for two time periods, 1961-1990 and 2070-2100. These initial estimates are adapted to 1142 observing stations by a correction using the vertical temperature gradient of the Standard Atmosphere and the difference between model and real topography. The analysis was performed using monthly observed mean temperature data from meteorological stations, along with 1142 simulated data. The PRECIS model with systematic errors was ameliorated by the application of the filter resulting in an improved mean temperature prediction of 66% above the mean square error for the dry months and above 49% for the wet months, for both scenarios under study. At the half-way point, the improvement was 68% for the A2 scenario and 69% for scenario B2. © 2011 Elsevier B.V.

Rakocevic M.,IAPAR | Martim S.F.,Embrapa Informatica Agropecuaria
International Journal of Biometeorology | Year: 2011

To assess differences in the lag-effect pattern in the relationship between yerba-mate biennial growth and environmental factors, a time-series analysis was performed. A generalized Poisson regression model was used to control time trends, temperature, growing degree days (GDD), rainfalls and night length (NL). It was hypothesized that the active growth and growth pauses in yerba-mate are controlled endogenously and modified by environment, and that genders would respond differently to environmental modifications. The patterns in the lag effect from the distributed-lag models were similar to those of time-series models with meteorological data means with lag = 0. GDD and NL were principal factors affecting biennial yerba-mate shoot elongation and the number of green leaves of females grown in monoculture, besides their significant effects on metamer emission and leaf area in males grown in monoculture. NL also had a significant influence on shoot elongation and leaf area of both genders grown in forest understorey (FUS), indicating that yerba-mate growth is synchronized by an internal clock sensitive to temperature adjustments. The morphological plasticity and the adaptation efforts of yerba-mate were more pronounced in monoculture than in FUS. Sexual dimorphism was expressed-males were more sensitive to environmental changes than females, especially in monoculture. Growth modifications were much more intense when plants were grown in a cultivation system that is less like yerba-mate natural habitat (monoculture) than in one resembling its natural habitat (FUS). Our data support the ecological specialization theory. © 2010 ISB.

Alho C.J.R.,Anhanguera-Uniderp University | Silva J.S.V.,Embrapa Informatica Agropecuaria
Animals | Year: 2012

Flooding throughout the Pantanal is seasonal. The complex vegetative cover and high seasonal productivity support a diverse and abundant fauna. A gradient in flood level supports a range of major habitats in a complex mosaic with annual seasonality. The rivers and streams are lined with gallery forests, and other arboreal habitats exist in the more elevated areas. The remainder is either grasslands or seasonally flooded grasslands. The regional flora and fauna are adapted to annual water fluctuation. However, an inter-annual series of higher or lower rainfalls has caused either severe floods or drastic dry seasons. Large scale climate phenomena such as greenhouse gases, El Niño and La Niña influence the seasonality of floods and droughts in the Pantanal. Knowledge of severe floods and droughts, which characterize natural disasters, is fundamental for wildlife management and nature conservation of the Pantanal. Plants and wild animals, for example, are affected by tree mortality in riparian forest after extreme flooding, with consequent habitat modification for wild animals. In addition, human activities are also affected since cattle ranching and ecotourism are economically important in the region, and when seasons with unusual floods or droughts occur, areas with human settlements are impacted. © 2012 by the authors; licensee MDPI, Basel, Switzerland.

Barbedo J.G.A.,Embrapa Informatica Agropecuaria
Proceedings - 12th International Conference on Computational Science and Its Applications, ICCSA 2012 | Year: 2012

This paper presents a method to automatically count clustered soybean seeds using digital images. The method is based on classical morphological operations, and was designed to deal with the main difficulties imposed by images of soybean seeds, namely the clustering of the seeds, variations in the illumination, and low contrast between seeds and background. The proposal shows a good performance under a wide variety of condition. © 2012 IEEE.

Barbedo J.G.A.,Embrapa Informatica Agropecuaria
Proceedings - 12th International Conference on Computational Science and Its Applications, ICCSA 2012 | Year: 2012

This paper presents a method to count microorganisms and colonies in microscopic images. The method uses a series of morphological operations to create a representation in which the objects of interest are easily isolated and counted. The proposal is successful in most cases, properly dealing with some difficult situations like when the sizes of the objects vary strongly and when there is low contrast between the objects and the background. Studies are underway in order to improve the performance of the method when dealing with strongly merged objects. © 2012 IEEE.

Porto de Carvalho J.R.,Embrapa Informatica Agropecuaria | Delgado Assad E.,Embrapa Informatica Agropecuaria | Medeiros Evangelista S.R.,Embrapa Informatica Agropecuaria | Da Silveira Pinto H.,University of Campinas
Atmospheric Research | Year: 2013

The aim of this study was to model the occurrence of extreme dry spells in the Midwest, Southeast and Southern regions of Brazil and estimate the return period of the phenomenon indicating the time when the occurrence is more severe. The generalized extreme value distribution was the best fit for a series of maximum dry spell number and the parameters estimated by the maximum likelihood method. The data series adherence to the probability distribution was verified by the Kolmogorov-Smirnov test and the percentile-percentile charts. The positive trend of dry spells was verified by the Mann-Kendall test and non-stationarity rejected by Dickey-Fuller and augmented Dickey-Fuller tests. The irregular distribution of rainfall in the growing season for the Midwest region has increased the number of dry spells. The increase of rainy days in the Southeast and the South resulted in a decrease of dry spells in these regions. Regarding the return period of one year, dry spells occurred from 5 to 25. days in the Midwest region meaning a loss of productivity for Brazilian agriculture if it happened between the flowering and grain filling phases, making it, therefore the region with the largest agricultural risk. When the intensity of the dry spells was analyzed for different return periods, the Southern region was the most vulnerable. © 2013 Elsevier B.V.

Loading Embrapa Informatica Agropecuaria collaborators
Loading Embrapa Informatica Agropecuaria collaborators