Xiangyang Sun

Changes in physical, chemical, and microbiological properties during the two-stage co-composting of green waste with spent mushroom compost and biochar.

This research determined whether the two-stage co-composting can be used to convert green waste (GW) into a useful compost. The GW was co-composted with spent mushroom compost (SMC) (at 0%, 35%, and 55%) and biochar (BC) (at 0%, 20%, and 30%). The combined addition of SMC and BC greatly increased the nutrient contents of the compost product and also improved the compost quality in terms of composting temperature, particle-size distribution, free air space, cation exchange capacity, nitrogen transformation, organic matter degradation, humification, element contents, abundance of aerobic heterotrophs, dehydrogenase activity, and toxicity to germinating seeds. The addition of 35% SMC and 20% BC to GW (dry weight % of initial GW) and the two-stage co-composting technology resulted in the production of the highest quality compost product in only 24 days rather than the 90-270 days required with traditional composting.

Effects of brown sugar and calcium superphosphate on the secondary fermentation of green waste

The generation of green waste is increasing rapidly with population growth in China, and green waste is commonly treated by composting. The objective of this work was to study the physical and chemical characteristics of composted green waste as affected by a two-stage composting process and by the addition of brown sugar (at 0.0%, 0.5%, and 1%) and calcium superphosphate (Ca(H2PO4)2·H2O) (at 0%, 3%, and 6%) during the second stage. With or without these additives, all the composts displayed two peaks in fermentation temperature and matured in only 30days. Compared to traditional industrial composting, the composting method described here increased the duration of high-temperature fermentation period, reduced the maturity time, and reduced costs. Addition of 0.5% brown sugar plus 6% calcium superphosphate produced the highest quality compost with respect to C/N ratio, pH, organic matter content, electrical conductivity, particle-size distribution, and other characteristics.

Application of Organic Amendments to a Coastal Saline Soil in North China: Effects on Soil Physical and Chemical Properties and Tree Growth

The ability of the following four organic amendments to ameliorate saline soil in coastal northern China was investigated from April 2010 to October 2012 in a field experiment: green waste compost (GWC), sedge peat (SP), furfural residue (FR), and a mixture of GWC, SP and FR (1∶1∶1 by volume) (GSF). Compared to a non-amended control (CK), the amendments, which were applied at 4.5 kg organic matter m−3, dramatically promoted plant growth; improved soil structure; increased the cation exchange capacity (CEC), organic carbon, and available nutrients; and reduced the salt content, electrical conductivity (EC), and exchangeable sodium percentage (ESP). At the end of the experiment in soil amended with GSF, bulk density, EC, and ESP had decreased by 11, 87, and 71%, respectively, and total porosity and organic carbon had increased by 25 and 96% respectively, relative to the CK. The GSF treatment resulted in a significantly lower Na++K+ content than the other treatments. CEC and the contents of available N, P, and K were significantly higher in the GSF-treated soil than in the CK and were the highest in all treatments. The FR treatment resulted in the lowest pH value and Ca2+ concentration, which decreased by 8% and 39%, respectively, relative to the CK. Overall, the results indicate that a combination of green waste compost, sedge peat and furfural residue (GSF treatment) has substantial potential for ameliorating saline soils in the coastal areas of northern China, and it works better than each amendment alone. Utilization of GWC and FR can be an alternative organic amendment to substitute the nonrenewable SP in saline soil amelioration.

Effects of rhamnolipid and initial compost particle size on the two-stage composting of green waste.

Composting is a potential alternative to green waste incineration or deposition in landfills. The effects of the biosurfactant rhamnolipid (RL) (at 0.0%, 0.15%, and 0.30%) and initial compost particle size (IPS) (10, 15, and 25 mm) on a new, two-stage method for composting green waste was investigated. A combination of RL addition and IPS adjustment improved the quality of the finished compost in terms of its physical characteristics, pH, C/N ratio, nutrient content, cellulose and hemicellulose contents, water-soluble carbon (WSC) content, xylanase and CMCase activities, numbers of culturable microorganisms (bacteria, actinomycetes, and fungi), and toxicity to germinating seeds. The production of a stable and mature compost required only 24 days with the optimized two-stage composting method described here rather than the 90-270 days required with traditional composting. The best quality compost was obtained with 0.15% RL and an IPS of 15 mm.

Effects of grazing intensity on soil labile organic carbon fractions in a desert steppe area in Inner Mongolia

Grazing can cause changes in soil carbon (C) level. This study aimed to elucidate the response of soil labile organic carbon (SLOC) under four different grazing intensities: non grazing (NG), 0 sheep·ha-1; light grazing (LG), 0.91 sheep·ha-1; moderate grazing (MG), 1.82 sheep·ha-1, and heavy grazing (HG), 2.73 sheep·ha-1. Results showed that there was no significant difference in total soil organic carbon (TOC) and soil inorganic carbon (SIC) content from three soil depths (0-15 cm, 15-30 cm, and 30-45 cm) under different grazing intensities. However, the SLOC including particulate organic carbon (POC), light fraction organic carbon (LFOC), and readily oxidizable carbon (ROC) content at a depth of 0-15 cm decreased with the increasing grazing intensity among LG, MG and HG. The SLOC content at depths of 15-30 cm under the NG and LG were significantly higher than that under the MG and the HG. The TOC and SLOC content decreased with increasing depths of soil horizons, but SIC content increased. The variation trend of the density of different soil carbon fractions and the ratio of individual SLOC fractions to TOC were similar to that of the soil carbon content of corresponding fractions. These results indicated that MG and HG treatments caused C loss at 0-30 cm; and SLOC was more sensitive than TOC in response to different grazing intensities.

Improving green waste composting by addition of sugarcane bagasse and exhausted grape marc.

The composting of lignocellulosic waste into compost is a potential way of sustainably disposing of a waste while generating a useful product. The current study determined whether the addition of sugarcane bagasse (SCB) (at 0, 15, and 25%) and/or exhausted grape marc (EGM) (at 0, 10, and 20%) improved the two-stage composting of green waste (GW). The combined addition of SCB and EGM improved composting conditions and the quality of the compost product in terms of temperature, water-holding capacity, particle-size distribution, coarseness index, pH, electrical conductivity, water-extractable organic carbon and nitrogen, microbial numbers, enzymatic activities, polysaccharide and lignin content, nutrient content, respiration, and phytotoxicity. The optimal two-stage composting and the best quality compost were obtained with the combined addition of 15% SCB and 20% EGM. With the optimized two-stage composting method, the compost matured in only 21days rather than in the 90-270days required for traditional composting.

Addition of fish pond sediment and rock phosphate enhances the composting of green waste

The objective of this work was to study the two-stage composting of green waste (GW) as affected by addition of fish pond sediment (FPS; at 0, 25, and 35%) and/or rock phosphate (RP; at 0, 10, and 15%). The combined addition of FPS and RP greatly accelerated GW degradation and improved compost quality in terms of composting temperature, windrow volume, pH, electrical conductivity (EC), cation exchange capacity (CEC), NH3 emission, microbial biomass, enzyme activities, nutrient content, and seed germination. The two-stage composting was optimal with the combined addition of 25% FPS and 15% RP. In addition to producing the highest quality compost product, the optimal combination resulted a mature compost in only 22days rather than in the 90-270days required with traditional composting.

Composted Green Waste as a Substitute for Peat in Growth Media: Effects on Growth and Nutrition of Calathea insignis

Peat mined from endangered wetland ecosystems is generally used as a component in soilless potting media in horticulture but is a costly and non-renewable natural resource. The objective of this work was to study the feasibility of replacing peat with different percentages (0, 10, 30, 50, 70, 90, and 100%) of composted green waste (CGW) as growth media for the production of the ornamental plant Calathea insignis. Compared with 100% peat media, media containing CGW had improved physical and chemical characteristics to achieve the acceptable ranges. Moreover, CGW addition had increased the stability (i.e., reduced the decomposition rates) of growth media mixtures, as indicated by comparison of particle-size distribution at the start and end of a 7-month greenhouse experiment. Addition of CGW also supported increased plant growth (biomass production, root morphology, nutrient contents, and photosynthetic pigment contents). The physical and chemical characteristics of growth media and plant growth were best with a medium containing 70% CGW and were better in a medium with 100% CGW than in one with 100% peat media. These results indicate that CGW is a viable alternative to peat for the cultivation of Calathea insignis.

Maturation of green waste compost as affected by inoculation with the white-rot fungi Trametes versicolor and Phanerochaete chrysosporium

ABSTRACT Green waste was separately inoculated on day 0 and day 14 with either Trametes versicolor or Phanerochaete chrysosporium to determine their effects on composting time and compost quality. Inoculation with T. versicolor and P. chrysosporium caused more rapid and higher increases in compost temperatures, increased the duration of the thermophilic temperature stage, and reduced the maturity time. Inoculation with T. versicolor and P. chrysosporium greatly increased the quality of the final composts in terms of pH, electrical conductivity, organic matter concentration, C/N ratio, germination index, and nutrient content. Inoculation with T. versicolor and P. chrysosporium also significantly increased the degradation of lignin by 7.1% and 8.2%, respectively, and increased the degradation of cellulose by 10.6% and 13.6%, respectively.

Using cow dung and spent coffee grounds to enhance the two-stage co-composting of green waste

The objective of this study was to determine the effects of cow dung (CD) (at 0%, 20%, and 35%) and/or spent coffee grounds (SCGs) (at 0%, 30%, and 45%) as amendments in the two-stage co-composting of green waste (GW); the percentages refer to grams of amendment per 100g of GW based on dry weights. The combined addition of CD and SCGs improved the conditions during co-composting and the quality of the compost product in terms of composting temperature; particle-size distribution; mechanical properties; nitrogen changes; low-molecular weight compounds; humic substances; the degradation of lignin, cellulose, and hemicellulose; enzyme activities; the contents of total Kjeldahl nitrogen, total phosphorus, and total potassium; and the toxicity to germinating seeds. The combined addition of 20% CD and 45% SCGs to GW resulted in the production of the highest quality compost product and did so in only 21days.