Composting of Tree-pruning Waste and Effect of Resulting Composts on Growth of Ruellia Brittoniana

By using the waste from tree-pruning in Fuzhou and adjusting the C/N ratio with chicken manure for composting, the resulting composts were evaluated as a potential substrate for plant growth. During the composting, a real-time monitoring on the aerobic fermentation was conducted to understand the changes in the nutrient content of the compost and their effect on the growth of the model plant, Ruellia brittoniana. A continual decline on the organic matters accompanied by an increase on the contents of nitrogen, phosphorus, potassium, and other nutrients in the compost was observed. On the 10th day of composting, the compost reached a constant internal temperature of 50℃, while its pH decreased gradually after an initial increase and stabilized after the 35th day. The moisture content of the compost decreased continuously throughout the process. The C/N ratio of the compost arrived at the fully decomposed stage (i.e., 15-20/1) on the 35th day. The height, leaf area, and dry biomass of the plants grown on the soil/compost mixtures were found superior to those on soil alone. When one part of soil was mixed with two parts of the compost, the nutrient content in the above-ground, as well as under-ground, parts of the plant was at its maximum. It was concluded that when the temperature was 45-49℃ (averaging 48℃), C/N at 19.50, and pH at 9, the compost was considered fully decomposed with the total nitrogen, phosphorus, and potassium contents of 1.28%, 1.73%, and 1.95%, respectively. And, on substrate with a mixing ratio of two parts compost to one part soil, the best result was obtained for the growth of R. brittoniana. It was expected that a compost could be generated from tree-pruning waste in the city to satisfactorily enrich the soil for municipal landscaping on viaducts.