Green Waste Composting And The Products As The Peat Substitutes In Growth Media

With increasing green waste in China, appropriate artificial intervention and promotion of their eco-utilization was probed, based on the composting treatment as a view of ecological resource and function. The green waste was suggested to recycle in the greenland ecosystem instead of being removed as solid wastes so as to promote the self-maintenance mechanism of greenland. The effects of additives on the process of composting and quality of products were mainly discussed; meanwhile, this study examined the feasibility of using compost products made from green waste replace some or all of the peat substrate which is commonly used for the cultivation of the ornamental plant. The application of green waste residues could solve the restriction about peat use due to greatly-reduced peat resources and wetland conservation destruction, improve the recycling of waste resources, and reduce the cost of substrate cultivation. Results showed that:(1) The results showed that the addition of bamboo vinegar and bacterial reagent affected the temperature, pH, EC, total N, P, K during composting; and furthermore, there existed interaction between bamboo vinegar and bacterial reagent. Total concentrations of P and K increased during composting, while total N increased less because of ammonia volatilization. Compared with the control, the addition of bacterial reagent accelerated the N loss, but the addition of a certain concentration of bamboo vinegar can keep more N.(2) The addition of a certain amount of bamboo vinegar can effectively promote bacterial reagent activity during composting; the concentrations of organic carbon and organic matter in compost products were lower than those in raw materials. The concentrations of total humic acid in compost products were reduced by 19%-40%from raw materials, and the lowest concentration was found in treatment A product, but the highest in treatment I product. Expect the treatment G, the C/N ratio was lower than 20 for products from other treatments. The germination index (GI) of the treatments B-I was greater than 0.8. The combination of 1:1000 (v:v) bamboo vinegar of 2L and bacteria reagent of organic waste of 0.5% had the best effect on green waste compost.(3) In the stage of the first temperature drop, the addition of red sugar and superphosphate promoted the speed of finished compost (30 d), and reduced the pH and EC values of the compost products. During the composting, the concentrations of nutrient elements increased; but the concentration of organic carbon decreased with the maximal decrease found in treatment I. The C/N ratio was lower than 20 in all compost products with the lowest in treatment F. The concentration of total humic acid was decreased by 5%-10%, but was increased the proportion in organic carbon by 1 %-10%, when compared with raw materials.(4) During composting, DOM (dissolved organic carbon) was extracted from compost and purified. The spectroscopic characteristics of the DOM were determined using ultraviolet-visible (UV-Vis), and fluorescence spectroscopy (FS). The result showed that at the final stage of composting, the UV-Vis and FS were similar in shape among all treatments, which focused on the fulvic acid (FA).When DOM from all samples was the same, the specific ultraviolet absorbance values at 254 nm and 280 nm (SUVA254 and SUVA280), the area of spectrum obtained from 226 nm to 400 nm (A226-400) and the ratio between the absorbance value at 280 nm and that at 472 nm (E280/E472) were increasing during composting, respectively, resulting in the non-humic substances being translated into humic substances, and the aromatization. The combination of 0.5% red sugar and superphosphate (C:P=1:100) had the best effect on the second stage of green waste compost.(5) This study examined the feasibility of using compost substrate made from green waste (The combination of 1:1000 (v:v) bamboo vinegar of 2L and bacteria reagent of organic waste of 0.5%) replace some or all of the original peat substrate (OP) commonly used for the cultivation of the ornamental plant Calathea rotundifola cv. Fasciata. The three growing media were OP (100%), OP+ CGW (50% each), and CGW (100%), which had the bulk density of<0.4g·cm-3, and the value of air space:water-filled porosity between 1:2-4, falling into the ideal ranges. The particle-size analysis of media at the start and end of the cultivation showed that media were degraded after planting, but CGW reduced media degradation; at the end of the 6-month experiment, the fraction of particles>1 mm was decreased by 39%,28%,14%in OP, OP+CGW and CGW, respectively. Plant growth was greatest with OP+CGW, and total biomass, plant height, crown diameter and other characteristics were greater than OP. Nearly 90% of root length was mainly distributed within the diameter of 0 mm-5.0 mm; and the specific root length in CGW was significantly lower than other treatments within the diameter of 2.0 mm-10.0 mm, in contrast, that of CGW was significantly higher than other treatments within the diameter of> 10.0 mm (P<0.05). The results indicated that, the CGW replace some or all of OP commonly used for the cultivation of the ornamental plant Calathea rotundifola cv. Fasciata, and the OP+CGW was the best.(6) This study examined the feasibility of using compost substrate made from green waste (the combination of 0.5% red sugar and superphosphate (C:P=1:100)) replace some or all of the original peat substrate (T1) commonly used for the cultivation of the ornamental plant Anthurium andraeanum. The bulk density and total porosity in T2-T7 (10%-100%V) were not significantly different from T1, but the decreasing air space was related with the increased volume of green waste substrate. The pH and EC values were increasing along with the increased proportion of compost product, and there existed significant differences for pH value (P<0.05). The plant height, fresh biomass, fresh root weight and the number of spathes in T2-T7 were bigger than T1. The results indicated that, the green waste compostproduct could replace all of OP commonly used for the cultivation of the ornamental plant Anthuriumandraeanum, and the 10%-70% green waste compost product as peat substitute was the best.