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Costa V.L.,IAC | de Maria I.C.,IAC | Camargo O.A.,IAC | Grego C.R.,Embrapa Monitoramento por Satelite | Melo L.C.A.,Federal University of Viçosa
Revista Brasileira de Engenharia Agricola e Ambiental | Year: 2014

In agricultural soils receiving sewage sludge and subjected to water erosion, may occur intense transport of phosphorus (P) to the lower parts of the landscape and eventually to water bodies. The objective of this study was to evaluate the spatial distribution of P in an Oxisol cultivated with maize. The treatments were evaluated with application of mineral fertilization (MF) and sewage sludge (SS). Soil samples were collected following a sampling grid of 69 points in each treatment at the beginning and at the end of the crop cycle, in an experimental area with 10% slope. There was a moderate spatial dependence of P in the soil in the treatment of MF, resulting in higher concentrations of P in the deeper layers of the soil caused by erosion. The same standard was observed for the soil attributes sum of bases, cation exchange capacity and soil organic matter. Conversely, when SS was applied there was a randomized distribution of P in the plots because of the non-uniform manner of its application. Such random distribution of P showed correlation with soil organic matter.

Andrade R.G.,Embrapa Monitoramento por Satelite | Sediyama G.C.,Federal University of Viçosa | da Paz A.R.,Federal University of Paraiba | Lima E.P.,Embrapa Solos | Facco A.G.,Federal University of Espirito Santo
Pesquisa Agropecuaria Brasileira | Year: 2012

The objective of this work was to evaluate surface biophysical parameters of the Pantanal biome, Brazil, by the application of geotechnologies. The Sebal algorithm, Modis imagery, and land use and land cover map were used. The obtained results for NDVI, surface temperature, albedo, daily sensible heat flux, daily net radiation and daily actual evapotranspiration were consistent with literature data for the different land use and land cover classes, and corroborate the analytical and synoptic capacity of Sebal estimates. These results show the potential of geotechnologies in the implementation of models or algorithms developed for the understanding of biophysical process dynamics related to the soil-plant-atmosphere interactions in Pantanal.

Mander T.,University of Tartu | Mander T.,IRSTEA | Dotro G.,Cranfield University | Ebie Y.,Japan National Institute of Environmental Studies | And 8 more authors.
Ecological Engineering | Year: 2014

A literature analysis of 158 papers published in international peer-reviewed journals indexed by the Thomson Reuters Web of Knowledge from 1994 to 2013 showed that CO2C emission was significantly lower in free water surface (FWS) constructed wetlands (CW) than in subsurface flow (SF) CWs (median values from 95.8 to 137.0mgm-2h-1, respectively). In vertical subsurface flow (VSSF) CWs the CH4C emission was significantly lower than in horizontal subsurface flow (HSSF) CWs (median values 3.0, 6.4, and 4.0mgm-2h-1, respectively). There were no significant differences in N2ON emission in various CW types (median for FWS, VSSF and HSSF CWs: 0.09, 0.12, and 0.13mgm-2h-1 correspondingly).The highest value of emission factor (EF) of CH4 ((CH4C/inflow TOCin)*100%) was found for FWS CWs (median 18.0%), followed by HSSF CWs (3.8%), and VSSF CWs (1.28%). Median values of N2O EFs ((N2ON/inflow TNin)*100%) differed significantly in all three CW types: 0.34% for HSSF, 0.11% for FWS, and 0.018% for VSSF CWs.We found a significant correlation between TOCin and CH4C emission and between the TNin and N2ON emission values for all of the types of CWs we studied.Hybrid CWs (e.g., the subsequent combination of VSSF, HSSF and FWS CWs) are beneficial from the point of view of both water purification and minimization of greenhouse gas (GHG) emissions. Likewise, intermittent loading in VSSF CWs and macrophyte harvesting in HSSF and FWS CWs can mitigate GHG emissions. © 2013 Elsevier B.V.

Dematte J.A.M.,University of Sao Paulo | Terra F.S.,University of Sao Paulo | Quartaroli C.F.,Embrapa Monitoramento por Satelite
Bragantia | Year: 2012

Remote sensing has a high potential for environmental evaluation. However, a necessity exists for a better understanding of the relations between the soil attributes and spectral data. The objective of this work was to analyze the spectral behavior of some soil profiles from the region of Piracicaba, São Paulo State, using a laboratory spectroradiometer (400 to 2500 nm). The relations between the reflected electromagnetic energy and the soil physical, chemical and mineralogical attributes were analyzed, verifying the spectral variations of soil samples in depth along the profiles with their classification and discrimination. Sandy soil reflected more, presenting a spectral curve with an ascendant form, opposite to clayey soils. The 1900 nm band discriminated soil with 2:1 mineralogy from the 1:1 and oxidic soils. It was possible to detect the presence of kaolinite, gibbsite, hematite and goethite in the soils through the descriptive aspects of curves, absorption features and reflectance intensity. A relation exists between the weathering stage and spectral data. The evaluation of the superficial and subsuperficial horizon samples allowed characterizing and discriminating the analytical variability of the profile, helping to soil distinguishing and classification.

Valladares G.S.,Federal University of Piauí | Gomes A.D.S.,Federal Rural University of Rio de Janeiro | Torresan F.E.,Embrapa Monitoramento por Satelite | Rodrigues C.A.G.,Embrapa Monitoramento por Satelite | Grego C.R.,Embrapa Monitoramento por Satelite
Pesquisa Agropecuaria Brasileira | Year: 2012

The objective of this work was to evaluate the construction of an erosion susceptibility map for a rural area of the municipality of Guararapes, SP, Brazil, using a multicriteria additive model. Digital maps on the themes relief (declivity and length of the slopes), pedology (obtained at the field), land use and land cover of the region, and interpretation of the digital elevation model were used. The digital maps were treated in a geographic information system environment using the additive multicriteria method and were validated by the universal soil loss equation (USLE) model. Five erosion susceptibility classes were generated: low, moderate, high, very high, and extremely high. The risk map obtained by additive multicriteria had good correspondence with the USLE model. The erosion susceptibility map can be used for the agricultural and environmental planning of the rural area of the municipality of Guararapes.

Bolfe E.L.,Embrapa Monitoramento por Satelite | Batistella M.,Embrapa Monitoramento por Satelite
Pesquisa Agropecuaria Brasileira | Year: 2011

The objective of this work was to analyze the structural and floristic composition of agroforestry systems in Tomé-Açu, Pará, Brazil. Dendrometric data were obtained through an inventory of 40 sampling plots, with three sampling units each, comprising 120 sampling units with 10x10 m each. The average of 1,424.3 individuals per hectare belonging to 27 families and 54 species was inventoried. Considering the variability of vegetative stages, the different agroforestry systems (SAF) were divided into four hierarchical classes: SAF 1, SAF 2, SAF 3, and SAF 4, to set an classification system which can be used in other field evaluations and in digital classifications developed by means of remote sensing. Species observed in other agroforestry systems in the Amazon region were also relevant to this work, specially Theobroma cacao, Theobroma grandiflorum and Euterpe oleracea which, together, showed averages of 51% relative frequency, 69.2% relative density, 50.1% relative dominance, and 56.8% importance value index. The average data of the floristic diversity, abundance, basal area, and importance value index indicate that the agroforestry systems in the Tomé-Açu region are production systems with economic and environmental potential, if appropriate and rational management is adopted.

Victoria D.D.C.,Embrapa Monitoramento por Satelite | da Paz A.R.,Federal University of Paraiba | Coutinho A.C.,Embrapa Informatica Agropecuaria | Kastens J.,Kansas Applied Remote Sensing | Brown J.C.,University of Kansas
Pesquisa Agropecuaria Brasileira | Year: 2012

The objective of this work was to evaluate a simple, semi-automated methodology for mapping cropland areas in the state of Mato Grosso, Brazil. A Fourier transform was applied over a time series of vegetation index products from the moderate resolution imaging spectroradiometer (Modis) sensor. This procedure allows for the evaluation of the amplitude of the periodic changes in vegetation response through time and the identification of areas with strong seasonal variation related to crop production. Annual cropland masks from 2006 to 2009 were generated and municipal cropland areas were estimated through remote sensing. We observed good agreement with official statistics on planted area, especially for municipalities with more than 10% of cropland cover (R2 = 0.89), but poor agreement in municipalities with less than 5% crop cover (R2 = 0.41). The assessed methodology can be used for annual cropland mapping over large production areas in Brazil.

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.

Bolfe E.L.,Embrapa Monitoramento por Satelite | Batistella M.,Embrapa Monitoramento por Satelite | Ferreira M.C.,University of Campinas
Pesquisa Agropecuaria Brasileira | Year: 2012

The objective of this work was to evaluate the correlation between spectral variables and aboveground carbon stock of agroforestry systems in the region of Tomé-Açu, PA, Brazil. Twenty-four vegetation indices from three groups (simple ratio, normalized difference, and complex), calculated from images of the TM/ Landsat-5 sensor acquired in 2008, were tested. The obtained variables were correlated, by means of simple linear regression, to carbon stock from four agroforestry systems with different ages and floristic composition. The correlations obtained among spectral variables and carbon stock were significant in 47% of the tested indices and changed according to the differences in biomass of the analyzed systems. The best correlations were obtained by the simple ratio and normalized difference indices in young agroforestry systems, and by complex vegetation indices in older agroforestry systems.

Teixeira A.H.C.,Embrapa Monitoramento por Satelite | Tonietto J.,Embrapa Uva e Vinho | Leivas J.F.,Embrapa Monitoramento por Satelite
Pesquisa Agropecuaria Brasileira | Year: 2016

The objective of this work was to develop and apply water balance indicators to be scaled up in the wine grape (Vitis vinifera) growing regions of the municipalities of Petrolina and Juazeiro, in the states of Pernambuco and Bahia, respectively, Brazil, simulating different pruning dates along the year. Previous energy balance measurements were used to relate the crop coefficient (Kc) with the accumulated degree-days (DDac). This model was applied to scale up the water balance indicators during the growing seasons. When irrigation water was available, the best pruning periods were from May to July, due to the better natural thermal and hidrological conditions. More care should be taken for pruning done in other periods of the year, regarding the effect of increasing thermal conditions of wine quality. The water balance indicators, both successfully developed and applied, allow large-scale analyses of the thermohydrological conditions for wine grape production under the semiarid conditions of the Brazilian Northeast.

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