菌渣垫料堆肥过程碳素物质转化规律

好氧堆肥是一种有效处理农业废弃物的方法,有利于实现农业资源的循环利用。但堆肥也有它的缺点,堆肥过程中的碳素损失是造成温室气体形成的重要原因。因此研究碳素在堆肥过程中的转化规律对于如何减少堆肥潜在的负面环境影响十分重要。该研究以生猪养殖发酵床废弃垫料及秀珍菇菌渣为原料,利用强制通风静态堆肥技术研究垫料和菌渣不同配比及添加EM菌剂对堆肥过程碳素物质转化的影响。结果表明,堆肥过程中总有机碳呈逐渐下降趋势;胡敏酸呈逐渐增加的趋势;微生物量碳和可溶性碳呈先增后降的变化趋势。堆肥结束时,碳素降解率为5.7%~10.2%,胡敏酸增加了56.0%~131.0%,可溶性有机碳增加了54.5%~81.5%,微生物生物量碳增加了31.7%~73.4%。以垫料为主料的堆肥处理碳素损失高于以菌渣为主料的处理,添加EM菌剂可以加速有机质的矿化分解和提高腐殖质化指数。

Change of carbon substance characteristics during composting of waste packing and fungus chaff

Aerobic composting is increasingly recognized as a viable treatment method for animal manure due to the possible recycling of its end-product (composts) in agriculture. However, carbon loss during composting may result in the formation of greenhouse gases. Thus, it is important to investigate changes of carbon during composting and to develop methods for conserving carbon and reducing potential negative environmental impacts. In this study, an experiment was conducted to study the carbon transformation and greenhouse gas emission in composting of waste packing and fungus chaff by using static forced-air composting boxes. Waste packing and fungus chaff were mixed according to the weight ratio (4:6 or 6:4) with or without EM microbial agent addition (MAA), respectively. The original composting materials were adjusted to the same C/N ratio (30:1) by adding urea, and then composted in a static forced-air composting box. Temperature was measured every day. Compost samples were taken on days 0, 10, 20, 25, 30, 35, 40 and 45 after the start of the experiment, respectively, and then used to determine total organic carbon (TOC), water-soluble organic C (WSOC), microbial biomass C (MBC), and humic acids concentrations. The results showed that during composting, for all treatments the TOC decreased rapidly in the first 20 days and then decreased gradually. This could be explained by the fact that microorganisms rapidly consumed the carbohydrates released during the degradation of carbon source. Interestingly, TOC were lower in the treatments with EM-MAA than the treatments without EM-MAA. The MBC gradually increased and peaked on day 20 after treatment, and then gradually decreased. However, it was significantly increased by 31.7%~73.4%for different treatments in the end-products compared to the initial mixed composting materials. In addition, the EM-MAA addition increased the MBC by 8.4%~7.2%, respectively. A similar trend in MBC was found in the WSOC compost. During composting, the humification process resulted in increased humic acids and decreased fulvic acids. At the end of composting, humic acid contents in T3 and T4 treatments increased by 63.3% and 32.4% than those of T1 and T2 treatments, respectively. The humification index (HI) of T3 treatment was 95.2% higher than that of T1 treatment, and the HI of T4 treatment was increased by 222.8% than that of T2 treatments. It indicated that EM agents addition accelerated the organic matter mineralization and increased the HI of the composts. After 45 days, the degradation rates of original carbon were 5.7%~10.2%, and the humic acid, DOC, and MBC in the compost were increased by 56.0%~131.0%, 54.5%~81.5% and 31.7%~73.4%, respectively, compared to their initial values. Total carbon loss was significantly higher in the composts with waste padding than the composts with fungus chaff. It was concluded that the fungus chaff could be used to reduce carbon loss during composting.