title: Soil, land use time, and sustainable intensification of agriculture in the Brazilian Cerrado region.
abstract: 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 Corg(38%) and Ntot(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+2than 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.
authors.affiliation: Rural Extension and Agricultural Research Institute of Santa Catarina, Rod. Admar Gonzaga, 1347, Florianópolis, SC, 88034-901, Brazil. klebertrabaquini@epagri.sc.gov.br.
authors.forename: Kleber
authors.initials: K
authors.lastname: Trabaquini
authors.affiliation: National Institute for Space Research, Remote Sensing Division, Av. dos Astronautas, 1758, São José dos Campos, SP, 12227-010, Brazil.
authors.forename: Lênio Soares
authors.initials: LS
authors.lastname: Galvão
authors.affiliation: National Institute for Space Research, Remote Sensing Division, Av. dos Astronautas, 1758, São José dos Campos, SP, 12227-010, Brazil.
authors.forename: Antonio Roberto
authors.initials: AR
authors.lastname: Formaggio
authors.affiliation: National Institute for Space Research, Remote Sensing Division, Av. dos Astronautas, 1758, São José dos Campos, SP, 12227-010, Brazil.|College of Life and Environmental Sciences, University of Exeter, Exeter, EX4 4RJ, UK.
authors.forename: Luiz Eduardo Oliveira E Cruz
authors.initials: LE
authors.lastname: de Aragão
mesh_terms: D000383:Agriculture / Q000379:methods / Q000639:trends*; D001938:Brazil; D004784:Environmental Monitoring; D005308:Fertilizers / Q000032:analysis*; D063809:Satellite Imagery / Q000706:statistics & numerical data*; D012987:Soil / Q000737:chemistry*
chemical_list: D005308:Fertilizers; D012987:Soil
keywords: Agriculture; Cerrado; Food security; Land use change; Remote sensing; Soil nutrients