Lixiviação de nitrogênio e fósforo em solos tratados com lodo de esgoto e água residuária de suinocultura

Abstract

The cycling of nutrients is one of the most important advantages of the application of waste in soils for agricultural purposes, representing a proper and inexpensive destination. However, after application, leaching of the constituents of such wastes can contaminate groundwater and soil, depending on the soil to which they are applied. Therefore, the objective of the present study was to evaluate the leaching of ammonium, nitrate, and phosphate in dystrophic Yellow-Red Latosol (YRL), dystroferric Red Latosol (RL), and dystrophic Yellow-Red Argisol (YRA), with and without sewage sludge (SS), under successive applications of swine wastewater (SW), deionized water (DW), and ionic solution (IS). The experiment was conducted using PVC columns with samples of deformed soils. The profi le layers were preserved, and SW, DW, or IS were applied to soil surface ten times, with intervals of seven days. The leachate was collected and the concentrations of ammonium, nitrate, and phosphate were determined by ion chromatography. The application of SS increased the amounts of leached ammonium in YRL and of leached nitrate in YRL, RL, and YRA. The application of SW did not affect the amount of leached ammonium and increased the amount of leached nitrate in the three soils. The amounts of leached ammonium and nitrate in the soils obeyed the following ascending order: YRA < RL < YRL. The application of SS and SW did not affect the amount of leached phosphate in the three soils analyzed.