Abstract

The aim of this study was to evaluate the changes produced in the chemical, acid-base and structural properties of soil amended (biosolids) and humic acids HAs incubated at different times.In the current work the amendments were conducted with biosolids at different doses (30, 90 and 180 t ha-1) on Colina (CLN) soil for 1, 2, 4 and 6 months.The acid-base characterization of extracted humic acids (HAs) showed a slight impact on Atotal (total acidity, mEq g-1), at 30 and 90 t ha-1 while at 180 t ha-1 the greatest increase was observed from 10.5±1.61 (control) to 17.9±0.30 (6 months of incubation). without evolution over the incubation time. The Aphenolic (phenolic acidity, mEq g-1) acidity behaves similarly while Acarboxylic (carboxylic acidity mEq g-1)) remains constant over time and applied doses. The application of 13C solid state NMR technique revealed higher abundance of aromatic C (CLN 43.5%) over alkyl C (21.4%) compounds. Aromatic C presents a decrease at high biosolid doses, which occurs simultaneously with alkyl C increase when using the same surveyed doses. Therefore, it might be considered that through the addition of biosolids, components such as fatty acids, amino acids or paraffinic structures are incorporated. As a result of biosolids addition, carboxylic C content remains steady, which agrees with the Accarboxylic behavior previously determined.