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| Effects of organic acid additives on nitrogen loss in low C/N ratio during composting |
| Received:October 20, 2021 |
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| KeyWord:organic acid;composting;low C/N;ammonia volatilization;organic nitrogen form |
| Author Name | Affiliation | E-mail | | XUE Wentao | Institute of Plant Nutrition, Resources and Environment, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China | | | SUN Hao | Institute of Plant Nutrition, Resources and Environment, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China | | | SUN Qinping | Institute of Plant Nutrition, Resources and Environment, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China | | | ZHANG Ling | Institute of Plant Nutrition, Resources and Environment, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China | | | WU Rong | Institute of Plant Nutrition, Resources and Environment, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China | | | TIAN Ye | Institute of Plant Nutrition, Resources and Environment, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China | | | CHEN Yishan | Institute of Plant Nutrition, Resources and Environment, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China | | | ZOU Guoyuan | Institute of Plant Nutrition, Resources and Environment, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China | | | LIU Shanjiang | Institute of Plant Nutrition, Resources and Environment, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China | liushanjiang@263.net |
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| Abstract: |
| Ammonia volatilization as a result of composting processes has raised public concern. The study of ammonia emission control technology in composting can provide a reference for effective control of nitrogen loss. Studies on this ammonia emission and its control can provide practical technology for efficient nitrogen loss control. To reduce ammonia volatilization and nitrogen loss in the process of composting, chicken manure, corn straw, and bacterial residue were composted aerobically for 41 days in static forced-aeration composting reactors. The effects of two organic acids（citric acid and oxalic acid）on ammonia emission reduction and nitrogen transformation in composting process under low C/N（15）conditions were investigated in this study. The results showed that 5%（fresh weight）citric acid and oxalic acid addition increased the number of days with a maximum temperature above 50 ℃ and the number of consecutive high temperature days as well as reduced the pH value of the initial compost by 1.70 and 1.88. Oxalic acid had a significant effect on ammonia emission reduction during the fermentation period of composting, while the reduction of ammonia volatilization by citric acid addition was primarily concentrated in the first 10 days of composting, and then the ammonia volatilization rate increased rapidly. Compared with the control treatment, citric acid and oxalic acid addition treatments reduced the cumulative ammonia volatilization by 44.15% and 69.57% and reduced total nitrogen loss by 25.16% and 48.54%, respectively. Nitrogen in compost mainly exists in the form of organic nitrogen. Compared with the control treatment, citric acid and oxalic acid addition also increased the organic nitrogen by 9.44% and 23.13% and increased the amino acid nitrogen by 11.23% and 15.53%, respectively. Furthermore, the amide nitrogen content increased by 18.43% and 39.99%, respectively. The addition of citric acid and oxalic acid increased the content of inorganic nitrogen at the end of composting, the ammonium nitrogen was raised by 68.13% and 408.48%, and nitrate nitrogen was raised by 17.94% and 45.75%, respectively. The contents of organic carbon decreased by 31.44%, 22.16%, and 15.70% in control, citric acid treatment and oxalic acid treatment, respectively. All treatments met the relevant requirements of composting maturity based on temperature, fecal coliform number, and ascaris egg mortality. However, the seed germination index of oxalic acid treatment did not meet the non-toxic standard. The results of the study indicates that adding organic acids has significant effects on nitrogen loss reduction, and oxalic acid is a better choice than citric acid. However, the addition amount and method of oxalic acid as harmless composting products needs to be further studied. |
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