Soil, land use time, and sustainable intensification of agriculture in the Brazilian Cerrado region.

The Brazilian Cerrado area is in rapid decline because of the expansion of modern agriculture. In this study, we used extensive field data and a 30-year chronosequence of Landsat images (1980-2010) to assess the effects of time since conversion of Cerrado into agriculture upon soil chemical attributes and soybean/corn yield in the Alto do Rio Verde watershed. We determined the rates of vegetation conversion into agriculture, the agricultural land use time since conversion, and the temporal changes in topsoil (0-20 cm soil depth) and subsurface (20-40 cm) chemical attributes of the soils. In addition, we investigated possible associations between fertilization/over-fertilization and land use history detected from the satellites. The results showed that 61.8% of the native vegetation in the Alto do Rio Verde watershed was already converted into agriculture with 31% of soils being used in agriculture for more than 30 years. While other fertilizers in cultivated soils (e.g., Ca+2, Mg+2, and P) have been compensated over time by soil management practices to keep crop yield high, large reductions in C org (38%) and N tot (29%) were observed in old cultivated areas. Furthermore, soybean and cornfields having more than 10 years of farming presented higher values of P and Mg+2 than the ideal levels necessary for plant development. Therefore, increased risks of over-fertilization of the soils and environmental contamination with these macronutrients were associated with soybean and cornfields having more than 10 years of farming, especially those with more than 30 years of agricultural land use.

Caracterização de lavouras cafeeiras, utilizando técnicas de geoprocessamento e sensoriamento remoto, no município de Umuarama - PR / Characterization of coffee crops using techniques of geoprocessing and remote sensing in the city of Umuarama - PR

O sensoriamento remoto e o geoprocessamento são geotecnologias importantes no apoio ao levantamento de dados da agricultura, permitindo estudos e o entendimento das relações ambientais em que uma determinada cultura está inserida. Neste trabalho,objetivou-se, relacionar as variáveis físicas, como, altimetria, declividade e tipo de solo com o agrossistema cafeeiro existente no município de Umuarama-PR pelo uso de geotecnologias. Foi utilizada a imagem do satélite LANDSAT 5/TM (Thematic Mapper) com data de passagem em 02/07/2007 e o software SPRING 4.3.3. As bandas 3, 4 e 5 do sensor TM foram restauradas, resultando em imagens de 15 m de resolução espacial e, posteriormente, constituindo a composição colorida RGB, na sequência TM4, TM5, TM3, a qual foi empregada na identificação das lavouras cafeeiras por meio de interpretação visual. Para o estudo do relevo, foram utilizados dados da missão SRTM, os quais possibilitaram o conhecimento da altimetria e declividade da região. A imagem do sensor TM possibilitou a execução da classificação visual e consequente identificação das lavouras cafeeiras com alta precisão. Quanto ao relevo, verificou-se que aproximadamente 99 por cento das lavouras cafeeiras estão localizadas entre 380 e 480 metros de altitude e que 90 por cento destas estão situadas em declividades de até 8 por cento de inclinação. Em relação aos solos, observou-se que 89 por cento dos cafeeiros são cultivados sobre Latossolo Vermelho distrófico, de textura arenosa.

The remote sensing and geoprocessing are important geotechnologies in support of the survey data of agriculture, enabling studies and understanding of environmental relations in which a particular culture is insert. The objective of this work was to relate the physical variables, such as altimetry, slope and soil type with the coffee agrosystems in Umuarama-PR through the geotechnologies. The image of the LANDSAT 5/TM (Thematic Mapper) dated in 02/07/2007 and the software SPRING 4.3.3 were used for the image processing. The bands 3, 4 and 5 of the sensor TM were restored, which resulted in images of 15m spatial resolution and, later, creating the RGB color composition, which was used to identify the coffee crops through visual interpretation. For the relief map study, the data of the SRTM mission were applied, which enabled us to know the altimetry and declivity of the region. The image of the TM sensor enabled the visual classification and the consequent identification of the coffee crops with high precision. As for the relief area, it was noticed that about 99 percent of the coffee fields are located between 380 and 480 meters of altitude and that 90 percent of them are located in declivity of up to 8 percent of inclination. About the soils, it was observed that 89 percent of the coffee fields are grown over distrofic Red Latosol, of sandy texture.