Soil Amendment with a Lignite-Derived Humic Substance Affects Soil Properties and Biomass Maize Yield

A two-year pot experiment was set up to determine the ability of Actosol (Act) to improve soil properties and maize yields. The Act effects were compared to those of manure, nitrogen/phosphorus/potassium (NPK) and an additive-free control (Ctr). After years 1 and 2, the pH, sorption properties, total carbon (TC), total N (TN), available P and K contents, dehydrogenase activity (DHA), residuum (Re) and humic acids (HAs) were measured in coarse- and medium-textured soils. Maize yield, N, P and K were also quantified. The plant element uptake and soil quality index (SQI) were calculated. In both soil types, the Act increased the DHA, cation exchange capacity, bioavailable K, P, TC, TN, C HAs and C Re in the soils compared to the Ctr. The maize yield, K and P contents and their uptake by the maize increased in both soil types after Act application. The SQI increased by >50% with a single dose (Act1), almost doubling with a double dose (Act2) compared to the Ctr. With Act1 and Act2, the P and K uptake increased several-fold. The soil properties and maize yield after using Act demonstrated its utility in improving soil organic matter and maize growth and in disposing of waste.