Assessment of biochar on soil health and biological activity

Rafaella Denissa Muscalu

Bachelor's thesis

Abstract:

Biochar is the product obtained by heating biomass through a pyrolysis process at high temperatures and has emerged as a common soil amendment based on its potential to improve soil properties such as water retention, pH, and nutrient availability. However, there are dangers of ecotoxicological effects on the soil biota. The overall aim of the bachelor thesis is to evaluate the impact of biochar, derived from various waste materials such as coffee grounds, hops, spruce wood and cigarette butts, on soil health focusing especially on microbial activity, plant growth and potential ecotoxicity. Biochar-amended soils were incubated for 15 days and a series of assays were performed including dehydrogenase activity, bacterial quantification, phytotoxicity bioassay and an ecotoxicity test using Enchytraeus albidus. Biochar amendments have the potential to change soil pH and improve water retention. Cigarette butts’ biochar activated bacterial colonies, whereas coffee grounds biochar activated dehydrogenase activity, implying higher microbial metabolic capacity. Phytotoxicity tests indicated that the growth of plants was enhanced at higher levels by hops and spruce wood biochar, while higher application rates of coffee grounds biochar suppressed seedling growth. The reproduction test done on Enchytraeus albidus indicated that all biochar except for cigarette butts had a detrimental effect. The findings show that the effect of biochar on soil health is source-dependent, with important connotations for soil management application. The thesis reveals the need for biochar application adjustment based on concentration and type in an attempt to maximize its benefits while minimizing hazard to soil systems.

Keywords

Phytotoxicity, Biochar, Soil biota, Ecotoxicity, Microbial activity

Language used: English

Date on which the thesis was submitted / produced: 4. 4. 2025

Thesis defence

• Date of defence: 30. 5. 2025
• Supervisor: doc. Ing. Lenka Wimmerová, MSc Ph.D.
• Reader: Zuzana Vaňková, Ph.D.

Czech University of Life Sciences Prague

Faculty of Environmental Sciences

Bachelor programme:
Environmental Engineering