Changes in Stabile Organic Carbon in Differently Managed Fluvisol Treated by Two Types of Anaerobic Digestate

Biogas and anaerobic digestion has begun to be considered an important renewable and sustainable energy source. The sustainable development of the anaerobic digestion process depends largely on the ability to manage large amounts of by-products generated during the biogas production process. We hypothesized that the use of digestate increases the accumulation of C in stable forms. We supposed that the effect of digestate on soil depends on the land-use system, leading to different stratifications of C. The main task of our research was to ascertain changes in the amount of stabile organic carbon (SOCstabile) in digestate-treated soils. Two field experiments were performed using the same design in 2019–2020. We studied the fertilization effects of digestate on Fluvisol. Fertilization: control; separated liquid digestate 85 kg ha −1 N and 170 kg ha −1 170 N; separated solid digestate 85 kg ha −1 N and 170 kg ha −1 N. A randomized experimental design with three field replicates was used. In terms of carbon stabilization in Fluvisol, soil used for grassland showed an advantage over the arable soil. The study showed that digestate, especially solid digestate, contributes to C accumulation and stabilization in the soil.