Navegando por Autor "Chiba, Márcio Koiti"

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Spatial variability of soil chemical properties after coffee tree removal
(Sociedade Brasileira de Ciência do Solo, 2009-09) Vieira, Sidney Rosa; Guedes Filho, Osvaldo; Chiba, Márcio Koiti; Cantarella, Heitor
Assessing the spatial variability of soil chemical properties has become an important aspect of soil management strategies with a view to higher crop yields with minimal environmental degradation. This study was carried out at the Centro Experimental of the Instituto Agronomico, in Campinas, São Paulo, Brazil. The aim was to characterize the spatial variability of chemical properties of a Rhodic Hapludox on a recently bulldozer-cleaned area after over 30 years of coffee cultivation. Soil samples were collected in a 20 x 20 m grid with 36 sampling points across a 1 ha area in the layers 0.0–0.2 and 0.2–0.4 m to measure the following chemical properties: pH, organic matter, K + , P, Ca 2+ , Mg 2+ , potential acidity, NH 4 -N, and NO 3 -N. Descriptive statistics were applied to assess the central tendency and dispersion moments. Geostatistical methods were applied to evaluate and to model the spatial variability of variables by calculating semivariograms and kriging interpolation. Spatial dependence patterns defined by spherical model adjusted semivariograms were made for all cited soil properties. Moderate to strong degrees of spatial dependence were found between 31 and 60 m. It was still possible to map soil spatial variability properties in the layers 0–20 cm and 20–40 cm after plant removal with bulldozers.