SPATIAL VARIABILITY OF CHEMICAL SOIL ATTRIBUTES

Abstract

Abstract: Soil chemical attributes present great spatial and temporal variability, influencing the productive potential of crops. Thus, considering that soil fertility is one of the main conditioning factors for increased productivity, this study aims to identify the spatial variability and whether there is spatial dependence in soil chemical attributes (Ca, Mg, Al, H + Al, P and K) in an area cultivated under no-tillage, depending on the sampling grid used. The experimental area is located in the city of Itapaci - GO, where cultivation has been carried out in a no-tillage system for ten years. At the time of data collection sampling, the area was in post-harvest corn condition. A sampling grid with 50 points spaced at 100 m was established. Each sampling point was composed of 5 subsamples, at depths of 0.00 - 0.20 and 0.20 - 0.40 m. The points were georeferenced with a GNSS receiver to determine the variables. The soil samples were taken to the Soil Laboratory of IF Goiano Campus Ceres. The results were subjected to descriptive and geostatistical analysis. The highest coefficients of variation found were for Aluminum at both depths, and Phosphorus in the 0.20 - 0.40 m layer. The sampling grid used proved to be adequate, since all variables presented spatial dependence. It was possible to generate variability maps for each attribute, showing the patterns in the area, thus enabling localized management interventions.

Keywords: Spatial dependence. Geostatistics. GNSS. QGIS.