Nutrient dynamics in soil amended with contrasting biochars

Mariana Silovská

Bachelor's thesis

Abstract:

Biochar has consistently been shown to improve soil properties, resulting in higher soil fertility and crop yield. Biochar characteristics are feedstock-dependent and can vary significantly. Generally, biochar abounds with high carbon content, large surface area and high porosity, which provides a suitable habitat for microorganisms. However, some types of biochar bring along characteristics undesirable for the soil. The constraints of a particular biochar type may be overcome by mixing it with another type, resulting in a synergistic effect, as is intended for in this experiment. This thesis investigates the effects of biochar amendments, which include varying ratios of sludge (SB) and wood biochar (WB), on nutrient dynamics and metal pollutant levels in agricultural soil. SB enriches the soil of important nutrients, however, it tags along some pollutants, including heavy metals. A high level of carbon comes from WB, which also acts as a sorption material to the present pollutants, making them immobile. This experiment was conducted as a laboratory incubation experiment, in which six different SB/WB ratios were added to a Regosol soil, soil solution were sampled three times during 55 days. Tested ratios were WB0%, WB5%, WB10%, WB20%, WB30% and WB40%, in which the number stands for the percentage of WB in the biochar mix. results reveal significant effects on pH, redox potential (Eh) and total nutrient, metal, and organic carbon contents in the soil solution, highlighting the potential of this biochar mix to improve nutrient retention and reduce metal pollution. Findings demonstrate that higher WB ratios, particularly WB40%, effectively conserve carbon, reduce nitrogen leaching, and increase macronutrient availability. WB40% also shows the most effective reduction in leached metals, indicating the potential for soil metal immobilization and improved soil quality. This research provides valuable insights into optimizing biochar amendments for enhancing soil fertility, crop productivity, and environmental sustainability. Further exploration of higher WB ratios could deepen understanding and optimize biochar efficacy in agricultural systems.

Keywords

Fertility, Biochar, Sewage sludge, Incubation, Agricultural soil

Language used: English

Date on which the thesis was submitted / produced: 29. 3. 2024

Thesis defence

• Date of defence: 29. 5. 2024
• Supervisor: Ing. Zuzana Vaňková, Ph.D.
• Reader: Barbora Böserle Hudcová, Ph.D.

Czech University of Life Sciences Prague

Faculty of Environmental Sciences

Bachelor programme:
Environmental Engineering