Departmental Honors Project Title
Date of Award
College of Liberal Arts
Biochar is a charcoal-like substance produced from plant material such as food waste. Converting food waste into a useful product would mitigate environmental damage through reduced landfill inputs, reduced greenhouse gas production, and increased benefits to soils. I asked (1) if biochar improved plant growth and (2) if the effects of biochar varied among different samples of mixed food waste (batches) and between different biochar preparation times (treatments). Four independent batches of biochar were prepared with assorted, uncooked food waste collected from a university dining facility. Each batch was dried then placed in a covered ceramic pot at 260℃ for 3 or 6 hours under low oxygen (pyrolysis). Tomato plants (Solanum lycopersicum) were grown in soils with the eight batch-treatment biochar combinations or with no biochar (controls). Averaging over batches, the 3 and 6 hour treatments germinated significantly later than controls. Aboveground dry mass at 30 days did not differ significantly among the three treatments. Mean height growth rates (mm/day) were significantly higher in 3 and 6 hour treatments than in controls. Considering only biochar-treated plants, there was a significant interaction between pyrolysis time and batch for both germination time and height growth rate. Some batches germinated earlier when the biochar pyrolyzed for 3 hours was added, other batches when six hour biochar was added. Plants emerging later had faster growth rates, leading to no significant difference in size at 30 days. Both pyrolysis time and food waste source material had varying effects on plant growth. While biochar had no effect on mean dry mass at 30 days, complex effects on germination time and growth rate suggest that growing plants to maturity may lead to differences in plant size. Future studies should investigate effects of different food waste types on plant growth and assess nutrient content of source material.
Mazac, Rachel, "Assessing the Use of Food Waste Biochar as a Biodynamic Plant Fertilizer" (2016). Departmental Honors Projects. Paper 43.