Impact of sewage sludge application on the humus state of sod-podzolic soil of subcarpathia under energetic willow plantation

Abstract

Aim. To determine the impact of energetic willow fertilization with sewage sludge (SS) and manure on the change in the humus state of sod-podzolic soil of Subcarpathia under energetic willow plantation. Methods. Soil samples were collected on the experimental fi eld of Ivano-Frankivsk College of LNAU. The humus con- tent was determined according to DSTU 4289:2004; that of its labile forms – according to DSTU 4732:2007, the content of organic matter in SS and manure – according to GOST 27980-88. Results. The application of sewage sludge for energetic willow grown in sod-podzolic soil of Subcarpathia led to the increase in the total humus content by 0.5–1.1 % compared to the control (without fertilizers). The use of SS preconditioned the change in the humus quality, including the increase in humic acids in humus by 0.05–0.07 %, which promoted the increase in the share of stable humus up to 68–70 % and the stabilization of the humus state of sod-podzolic soil. Conclusions. The application of sewage sludge impacts the change in the indices of humus quality, in particular, its group composition. The level of humic acids content in humus increases with the increase in the dose of the introduced sewage sludge and manure, based thereon. It ensures the increase in the share of stable humus in soil, which, in its turn, conditions the stabilization of humus state of sod-podzolic soil. However, this dependence weakens with depth.