Spatial variability of crop and soil properties in a crop-livestock integrated system.






The knowledge of spatial variability soil properties is useful in the rational use of inputs, as in the site specific application of lime and fertilizer. The objective of this work was to map and evaluate the spatial variability of the corn and pasture, soil chemical and physical properties in crop-livestock integrated system. The study was conducted in an area of 6.9 ha of a Typic Paleudult in Sao Carlos, SP, Brazil. The summer crop corn was sowed together with the forage crop Brachiaria brizantha in the system of crop-livestock rotation. A regular hexagon sampling grid design with 6 sub-samples was adopted for each hectare. The values of soil P, K, Ca, Mg, and CEC, basis saturation, clay and sand were analyzed by traditional soil testing in georreferenced samples collected at 0?0.2 m depth. Soil electrical conductivity (EC) was measured with a contact sensor. The site was evaluated at the end of the corn season (April) and for the forage (October) by imageries from the Landsat 5 using remote sensing techniques and a geographic information system. Normalized difference vegetation index (NDVI) was used to interpret imageries. Spatial continuity of crop and soil properties was modeled using semivariograms. Maps contours of crop and forage were obtained by kriging, and maps of soil properties by using inverse distance weighting interpolation. Results from this study showed that the NDVI was associated with ECa and soil parameters indicating crop and pasture variations on crop-livestock integrated system. Sampling density adopted was insufficient for an adequate characterization of the spatial variability of soil parameters as pH, O.M., P, K, V%, CEC, clay and sand. Estimated VRT maps compared to estimated uniformly applied lime and P and K fertilizer recommendation indicate that VRT could be more adequate to lime and potash recommendation, and and would have little effect on P fertilization.


geostatistics soil fertility soil texture electrical conductivity field sensor veris landsat 5 ndvi

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