Spatial Variability of soil properties in intensively managed tropical grassland in Brazil.

For the intensification of tropical grass pastures systems the soil fertility building up by liming and balanced fertilization is necessary. The knowledge of spatial variability soil properties is useful in the rational use of inputs, as in the variable rate application of lime and fertilizers. PA requires methods to indicate the spatial variability of soil and plant parameters. The objective of this work was to map and evaluate the soil properties and maps the site specific liming and fertilizer need in a irrigated tropical pasture. The study was conducted in an area of 8 ha of pasture Mombaça-grass (Panicum maximum) irrigated and intensive managed in a rotational system with 48 paddocks in Sao Carlos, SP, Brazil. Soil samples were collected at 0?0.2 m depth with 6 sub-samples in each paddock. The values of soil P, K, CEC and basis saturation were analyzed by traditional soil testing. Apparent soil electrical conductivity (ECa) was measured with contact sensor. Spatial variability soil properties and site specific liming and fertilizer need were modeled using semivariograms and maps were obtained by kriging with Vesper software. Crop variation at this spatial scale was not affected by topography and other soil chemical properties related. NDVI and ECa had the same tendency of dry matter estimation. Results showed that the soil properties of study area are very homogeneous, and variable rate of potassium fertilizer has the potential to be adopted in the study area