采用EEM-FRI方法研究黑曲霉对牛粪堆肥腐熟及纤维素降解影响

为了优化堆肥工艺，提高堆肥产品质量，研究黑曲霉对牛粪堆肥腐熟度和纤维素降解的影响。该研究以牛粪为原料，小麦秸秆为辅料，以不添加黑曲霉为对照，分别添加1%、2%和3%的黑曲霉进行好氧堆肥，研究了黑曲霉不同添加量对腐熟度指标、养分含量、腐殖质组成以及纤维素组分的影响，并采用激发发射荧光光谱结合荧光区域积分（Excitation Emission Matrix fluorescence spectra -Fluorescence Regional Integration, EEM-FRI）对堆肥腐熟度进行评估。结果表明，与对照组相比，黑曲霉接种量为2%可快速提高发酵温度，高温期提前1d出现，胡敏酸含量较初期增加49.94 g/kg，富里酸较初期减少37.51 g/kg，并提高了腐殖化水平。黑曲霉接种量为3%时种子发芽指数提高了2.38%，总磷含量增加了22.3%，纤维素和半纤维素降解率分别是对照组的1.36、1.42倍，更有利于堆肥的腐熟。通过EEM-FRI法发现添加黑曲霉可促进有机物降解，并促进了腐殖质物质的形成，加快了堆肥腐熟。相关性分析表明，添加黑曲霉后，发酵物料总磷含量与纤维素、胡敏酸以及富里酸类物质之间的相关性显著，说明黑曲霉促进了纤维素的降解以及腐殖质类物质的形成。综合考虑堆肥腐熟度和纤维素降解水平，建议牛粪堆肥中黑曲霉添加量为2%～3%。该研究可为利用黑曲霉促进牛粪堆肥腐熟，提高有机肥品质提供支持。

Effects of Aspergillus niger on the maturity and cellulose degradation of cow manure composting using EEM-FRI method

A large number of cow dung can cause the severe environmental pollution if not properly disposed of, particularly for the large-scale intensive cattle farm. A clean and sustainable treatment, composting has been commonly applied to the organic wastes in recent years. However, the traditional composting process cannot fully meet the requirement of industrial production in modern livestock farming, due to the low cellulose degradation and product maturity. Previous studies show that Aspergillus niger can be utilized to accelerate the degradation of organic matter for better composting maturity. However, a systematic understanding is still lacking on the application of Aspergillus niger on cow dung composting at present. In this study, a systematic optimization was performed on the fermentation process in composting using a combination of fluorescence excitation-emission matrix (EEM) spectroscopy and fluorescence regional integration (FRI). An attempt was also made to clarify the effects of Aspergillus niger on cow manure compost maturity and cellulose degradation. Cow manure was mixed to the moisture content of about 60%, with the wheat straw as an auxiliary material. With no Aspergillus niger as the control treatment, 1%, 2%, and 3% Aspergillus niger were added for the aerobic composting. A composting experiment was carried out in 60L composting reactors for 40 days. The compost maturity was evaluated to determine the maturity index, nutrient content, humus composition, and cellulose degradation. The results showed that the inoculation of 2% Aspergillus niger rapidly increased the temperature, where the thermophilic phase appeared 1 day ahead of time, compared with the control treatment. The content of humic acid increased by 49.94g/kg, but the fulvic acid decreased by 37.51g/kg, compared with the initial stage, indicating the improved humification. Once the inoculation with Aspergillus niger was 3%, the seed germination index and the total phosphorus content increased by 2.38%, and 22.3%, respectively, whereas, the degradation rates of cellulose and hemicellulose were 1.36 and 1.42 times higher than those of the control treatment, indicating more conducive to compost maturity. The EEM-FRI demonstrated that a high maturity of compost was achieved with the inoculation of Aspergillus niger, indicating the high degradation of organic matter, and the formation of humus. A correlation analysis also showed that there was a significant correlation between the total phosphorus content and cellulose, humic acid, and fulvic acid. after adding Aspergillus niger. Consequently, the high compost maturity and cellulose degradation can be achieved to enhance the quality and nutrients of the products. The cow manure compost with 2%-3% Aspergillus niger can also be inoculated to efficiently promote the resource utilization of cow manure in cattle farms.