Study of composting from city garbage and pruning residues of roadside trees in Zentsuji, Kagawa [Japan]

A series of experiments were conducted to construct a system to compost city garbage and pruning residues of roadside trees. Results are summarized in the followings. 1. Mixing garbage and pruning residues was sufficient to obtain the required temperature for composting without inoculants to promote the process. 2. Decomposition process of pruning residues was a time-consuming process. For summer experiments, most of the hemicellulose and a part of the cellulose were decomposed during 2 to 3 months of the composting process, while most of the lignin remained intact. The process was even slower for winter experiments where approximately a half of the hemicellulose remained. 3. In the course of composting, offensive odor substances, ethyl acetate and ammonia, were generated. Addition of either 'Eco-taishi' or plaster reduced their generation by 30 to 50%. 4. Germination rates of Komatsuna (Brassica rapa var. peruviridis) seeds were tested in pot experiments by the application of compost. As to the compost produced in summer, the germination rate of as high as 92 to 100% was observed irrespective of application rates. Soil density was slightly reduced by the application of the compost. 5. Contrary to summer compost, germination rates tended to decrease when winter compost was applied at high rates.