Comparative environmental analysis of soil sampling methods in precision agriculture for lime application in Paraná State, Brazil

Precision agriculture (PA) provides techniques that favour the localized application of inputs allowing their rational use. This makes the PA a potential indicator of reduced operational costs, input volume, and environmental impacts. The objective of this study was to evaluate and compare the environmental effects of three different sampling methods used in PA for the lime application. The first sampling method evaluated was the grid sampling (GS). It was performed at a density of one sample per hectare in a 100 × 100 m georeferenced grid. The second method was the directed sampling, that was performed after defining the management zones by soil apparent electrical conductivity (ECa) using a soil electrical conductivity sensor. The lest sampling method was the Altitude-based management zone (AMZ) sampling that was developed based on altitude maps of the field. These sampling methods were tested in three different areas in the south of Brazil. This study evaluated the spatial variability of the lime volume in the soil and compared quantitatively and spatially the recommended application volumes achieved by each sampling method. Results highlighted that the sensor-directed soil sampling method was the alternative that would generate the lowest environmental impact.