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Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A dramatic increase in the amount of chicken manure is posing a great challenge on the social community, ecological environment, and human health, as the growing demand of chicken meat and eggs in China. Fortunately, composting process is an effective, sustainable, economic and natural way to recycle the decomposed organic materials, with an emphasis on the manure treatment prior to land application. Nevertheless, there are usually lots of odor emissions during the composting of nitrogen-rich chicken manure. The C/N ratio of raw materials markedly determines the compost maturity and the odor emissions during composting. At present, lots of previous studies focused on the effect of C/N ratio on the compost maturity and quality. However, only a few reports paid attention to the odor (NH3 or H2S) emissions during chicken manure composting. In this study, three C/N ratios, including 14, 18 and 22, were selected from the co-composted chicken manure and cornstalks as the bulking agent, to improve the compost quality, while decrease the odor emissions. An attempt was made to explore the comprehensive effect of C/N ratio on maturity and odor emissions (NH3 and H2S) during chicken manure composting. The aeration was in an intermittent mode (Sated 30 min, stopped 30 min), and the rate was 0.2 m³/h. The composting lasted 35 days, where the sampled on the day of 0, 3, 7, 14, 21, 28, 35, respectively. The basic physicochemical and maturity indexes were measured, including temperature (T), oxygen (O2), inorganic nitrogen content (NH+4-N, NO-3-N), pH value (pH), Electrical Conductivity (EC), C/N ratio, Germination Index (GI), and the element content (C, N and S). Odor emissions (NH3 and H2S) were continuously monitored daily. A canonical correspondence analysis (CCA) was also used to analyze the microbial community composition, as well as their correlation with physicochemical indexes and odor emissions. The results showed that the final compost with the C/N ratio of 14 was not mature, while both the treatment with the C/N ratios of 18 and 22 reached the maturity standard. In terms of odor emissions, the C/N ratio of 18 treatment had the highest NH3 emission, because of the higher degradation of organic matter. When the C/N ratio ranged from 18 to 22, the NH3 emission and total nitrogen (TN) loss decreased with the C/N ratio increased. In addition, the cumulative H2S emission and the total sulfur (TS) loss were the highest in the C/N ratio of 14 treatment, while those in the C/N ratio of 18 and 22 treatments greatly decreased, indicating no significant difference. Moreover, the C/N ratio of 18 treatment had the highest microbial diversity, compared with other two treatments during the whole composting period. Furthermore, the microbial community compositions in the C/N ratios of 14 and 18 treatments (Firmicutes) were significantly different from those in the C/N ratio of 22 treatment (Actinobacteria and Firmicutes). More importantly, the CCA showed high temperature, high pH, and hypoxic environment can be beneficial to the proliferation of Firmicutes, and thereby to promote the emission of H2S and NH3. In an opposite case, high abundance of Actinobacteria can decrease the H2S and NH3 emission. As such, the recommended C/N ratio was 18~22 during co-composting of chicken manure and cornstalk. Specifically, the appropriate ratio can also be determined according to the number of cornstalks. [ABSTRACT FROM AUTHOR]

With the development of intensive and large-size livestock farming, a large amount of livestock manure has brought environmental pollution in some areas. Aerobic composting is a widely-used and efficient technology for the treatment and utilization of organic waste, which realizes harmless treatment, quantity reduction, stabilization and reutilization. However, there are several issues such as low maturity degree of compost product and emission of polluting gases during the process of composting, moisture content (MC) is one of the most important factors of composting. In order to study the effects of initial MC on maturity and pollution gas emissions during the sheep manure composting and optimize the process conditions, an experiment was carried out in 60 L sealed fermenters for 35 days. In this research, sheep manure and cornstalk were used as raw composting materials. According to the different initial MC, high-humidity sheep manure without any cornstalk was set as MC75 treatment, cornstalks were thoroughly mixed with sheep manure in certain proportions to adjust the initial MC to be 70%, 65%, 60% and 55%, respectively. C/N ratio of the composting mixture of five treatments was adjusted to 22 approximately by adding urea. The chemical and physical characters and maturity indicators such as temperature, germination index, electric conductivity, and pH value were analyzed, and continuous monitoring of pollution gases (CH4, N2O, and NH3) were conducted. The results demonstrated that the sheep manure composting pile with the MC of 75% could not be activated successfully, the compost product still had the risk in farmland utilization because it did not experience the thermophilic period (>50 ℃). However, lots of greenhouse gases such as CH4 and N2O were released and the greenhouse gas emissions equivalent was the largest among all treatments during the experiment (41.4 g/kg). While the co-composting process could be started effectively for all treatments with sheep dung and cornstalks. MC70%, 65%, 60% and 55% treatments all entered into thermophilic stage and reached the peak values of temperature on the 2nd and 4th day, respectively. The thermophilic phase lasted for 8-10 d to reach the compost sanitary requirements. Moreover, the germination index of all treatments under the addition of cornstalks were higher than 80%, the electric conductivities were below 4 mS/cm and the pH values were in the range of 8 to 9 at the end of composting, which could be biologically non-toxic and meet the maturity standard completely. The treatment with the initial MC of 65% had long thermophilic phase (10 d) and high biodegradation degree, whose degradation rate of dry material reached 45%. Meanwhile, compared to the other treatments, the total nitrogen loss and the total greenhouse effects were decreased by 4.81%-16.99% and 7.56%-48.62%, respectively. Consequently, sheep manure with high moisture content should be collected and disposed frequently in sheep farming, and it is not environmentally friendly to pile up without any bulking agent. The optimal initial moisture content is about 65% in this study during the aerobic co-composting of sheep manure and cornstalk. In addition, the control of ammonia emissions by adding additives could be taken into account in future research. [ABSTRACT FROM AUTHOR]