不同C/N比对双孢蘑菇培养料发酵过程温室气体排放的影响

针对双孢蘑菇培养料发酵过程中物质能量转化效率低、CO_2和CH_4等温室气体排放量大等问题,采用自制强制通风发酵箱装置研究了不同碳氮比对培养料发酵过程中温室气体排放和碳氮物质转化的影响。结果表明:发酵过程中温室气体的排放主要以CO_2为主,CH_4、N_2O和NH_3的排放量较少,并且CO_2、N_2O和NH_3的累积排放量均随C/N比的增加而降低。C/N分别为28,33,38,43处理以温室气体形式损失的碳分别为46.16,37.44,33.04,31.76 g/kg,损失的氮分别为4.72,3.49,1.76,1.65 mg/kg。C/N为33的处理更适合微生物活性,有机物降解率高于其它处理。到发酵结束时,C/N分别为28,33,38,43处理的碳物质损失分别为36.55%,45.5%,37.22%,32.71%,氮物质损失分别为5.41%,13.84%,7.59%,16.33%;但随发酵的进行,全氮相对含量因有机物降解而浓缩,呈现增加趋势。综合考虑温室气体排放和培养料发酵质量两个方面的因素,在实际生产过程中可适当提高C/N比,采用C/N为33:1~38:1的培养料配方,在不影响发酵质量的同时可减少温室气体排放量。另外,由于温室气体的排放主要集中在高温期,高温期越长,排放的温室气体越多,因此在发酵过程中应加强管理,及时翻堆,以控制发酵温度和温室气体排放。

Effects of different C/N ratios on greenhouse gases emissions and carbon and nitrogen conversion during composting of cultural materials of A.bisporus

In fermentation process of culture materials ofA. bisporus, there are problems such as low conversion efficiency of organic matter, and a lot of greenhouse gas emissions, which not only influence the quality of composting products, but also cause the pollution in the surrounding environment. Therefore, greenhouse gas emissions have become an important issue in the production processes ofA. bisporus. In recent years, most researches have focused on the conversion efficiency of organic matter and dynamic changes of microbial community during the composting, while the regularity of greenhouse gas emissions is still poorly understood. To understand the regularity of the greenhouse gas emissions and to explore the relationship between greenhouse gas emissions and the conversion of organic matter, an experiment was conducted to quantify the greenhouse gase emissions (including CO2, CH4 and N2O), and meanwhile to determine the total carbon and nitrogen contents during the composting with different ratios of C/N. The fermentation experiment was conducted in a reaction chamber, and the rice straw and cow dung were used as raw materials. There were 4 treatments with the C/N ratios of 28:1, 33:1, 38:1 and 43:1, and each treatment had 3 replications. Fermentation lasted for 18 d, and the turning was done on the 7th and 14th day during the composting. The results showed that during the composting with the C/N ratios of 28, 33, 38 and 43, the average emission rates of CO2were 489.47, 400.70, 362.31 and 357.22 mg/(kg?h), the average emission rates of CH4 were relatively lower and ranged from 0.02 to 0.06 mg/(kg?h), and the average emission rates of N2O were 0.03, 0.02, 0.01 and 0.01 mg/(kg?h). The cumulative amount of CO2emissions was the largest, while the cumulative amounts of CH4, N2O and NH3 emissions were relatively lower during the composting with different C/N ratios. The cumulative amounts of CO2, N2O and NH3 emissions were increased with the increasing of the ratio of C/N. The lost carbon amounts in forms of gases were 46.16, 37.44, 33.04 and 31.76 g/kg and the lost nitrogen amounts in forms of gases were 4.72, 3.49, 1.76 and 1.65 mg/kg with the C/N ratios of 28, 33, 38 and 43, respectively. In addition, the degradation rate of organic matter with the C/N ratio of 33 was the highest among all treatments. At the end of composting, the lost carbon amounts were 36.55%, 45.5%, 37.22% and 32.71%, and the lost nitrogen amounts were 5.41%, 13.84%, 7.59% and 16.33% respectively with the C/N ratios of 28, 33, 38 and 43. The relative nitrogen content was concentrated with organic matter degradation, and continuously increased during the composting process. The C/N ratios of 33 and 38 had the highest fruit body yield and absolute biological efficiency ofA.bisporus, and there were no significant difference between these 2 treatments. Considering both greenhouse gas emissions and culture materials quality, C/N = 38 was the better treatment, which not only had the high quality, but also could reduce the emissions of greenhouse gases. Besides, greenhouse gas emissions mainly occurred in high temperature periods, and turning timely could also reduce the emissions of greenhouse gases. The results can provide a theoretical basis to further explore how to reduce the greenhouse gas emissions during the fermentation process of cultivated material ofA.bisporus.