The intensification of pig farming in Brazil has led to an increase of incorrect wastewater allocation, but fertigation emerges as a potential solution. The aim of this study was to evaluate the electrical conductivity (EC) and pH of surface runoff due to the application of pig farming wastewater (0, 75, 150, 225 and 300 m3 ha-1) and mineral fertilizer (0, 25%, 50%, 75% and 100% of the fertilizer recommendation) in a soil cultivated with soybean under different slopes (4%, 9%, 14%, 19% e 24%) and precipitation intensity (45, 60, 75, 90 e 105 mm h-1). The experiment was conducted using the Rotated Central Composite Design (RCCD), in a 2 x 4 factorial scheme, containing axial and central points, totaling 28 tests. The precipitation was simulated after the fertilizer application, and then the wastewater was collected to evaluate its pH and electrical conductivity. The results revealed that only pig farming wastewater showed significant effect to both electrical conductivity and pH. Moreover, it was verified that the salt concentration in the drained wastewater decreased as time went by.