Clay dispersal in soil treated with landfill leachate containing high concentrations of Na+ and K+: a case study

Abstract

Waste deposited in landfills undergoes decomposition and generates a liquid called leachate (LAS). Despite its high potential for environmental pollution, LAS has been used in agriculture because it is rich in carbon and nutrients. However, the effect of LAS application on soil clay dispersion remains inconclusive. Considering that the application of high concentrations of Na+ and K+ can cause long-term clay dispersion, the objective of this work was to evaluate clay dispersion in a clay Oxisol after 6 years of LAS application with a high concentration of Na+ and K+. The evaluation was conducted in a grain production experimental area of IDR-PR. For 6 years, two applications per year of LAS were performed, appling an amount equivalent to 28.6 kg ha-1 of total N. Before and after LAS application, soil sampling was performed, collecting 32 samples randomly in a 0-0.2 m depth. Analysis of clay dispersed in water, pH-H2O, pH-KCl, organic carbon, the cation bases: Ca2+, Mg2+, K+, and Na+ were performed, and estimated zero charge point, and ∆pH. The results showed that after 6 years, organic carbon and cation bases in soil increased. Dispersed clay rather a reduction of 11.2%. Thus, long-term application of LAS with high concentrations of Na+ and K+, did not increase clay dispersion in a clay Oxisol after 6 years and increases organic carbon and nutrients.