| As one of the five treatment technologies of agricultural waste in China,fertilizer technology is the focus of research in the field of waste resource utilization.Although fertilizer technology can eliminate all kinds of potential dangers in organic waste to the maximum extent,heavy metals and antibiotics resistance genes(ARGs)will still bring health risks to the human body through accumulation and migration.Therefore,to ensure the nutrient content of organic fertilizer,it is necessary to analyze the changes in key parameters such as heavy metal content,microbial community,and ARGs in the process of fertilizer production.Before direct application,a systematic risk assessment should be carried out to ensure the safety of organic fertilizer for soil,crops,and the human body.In this study,the key parameters of cattle manure and rice straw fertilizer production processes were analyzed.The quality of organic fertilizers,bacterial community,and ARGs abundance produced by aerobic and anaerobic fertilizer production processes were compared.Correlation analysis,redundancy analysis and network analysis were used to explore the internal correlation.The concentrations of TN,Cu,and Zn during aerobic and anaerobic fertilizer production were determined by near infrared spectroscopy(NIRS).Finally,the fertilizer efficiency and application risk of biogas slurry in peanut cultivation were comprehensively evaluated.The main conclusions are as follows:(1)The physicochemical properties of anaerobic and aerobic organic fertilizers were in a reasonable range,and the total nutrient(TON)content of anaerobic organic fertilizers was higher than that of aerobic organic fertilizers.However,the content of Cu and Zn in anaerobic fertilizers was always higher than that in aerobic composts.There was a certain correlation among the parameters of maturity degree.Fourier infrared spectroscopy(FTIR)analysis showed that the spectra of different fertilizer processes were similar,but the absorption intensity of each peak was different,and the fertilizer process was beneficial to improve the humification degree of materials.(2)The reliable prediction models of TN,Cu,and Zn were established by NIRS combined with different spectral data processing methods.Different combinations of methods had different effects on the accuracy of the model,but the prediction results of all models were excellent.The significant correlation between TN,Cu,and Zn indicated that the combination of metal and organic matrix makes NIRS respond to heavy metals.(3)The microbial community richness and composition of the two fertilizer processes were different,and the microbial community richness under anaerobic treatment was higher than that under aerobic treatment.Aerobic compost showed a better performance in reducing the abundance of ARGs and mobile genetic elements(MGEs).There was a correlation between ARGs,MGEs,dominant bacteria,and environmental factors.ARGs shared the common potential host.Environmental factors can directly affect the changes of ARGs and MGEs,and also indirectly affect the degree of fertilizer maturity of ARGs through MGEs.The heavy metal content and maturity of fertilizer were closely related to the destiny of ARGs.(4)The application of biogas slurry had a significant effect on soil and peanut.In the growth process of peanuts,biogas slurry was not only a nutrient provider but also the main source of heavy metals in soil and plants.The content of As and Hg in soil treated with biogas slurry increased significantly,and the potential ecological risk was higher.The content of Hg in peanut kernels exceeded the standard.Although the content of heavy metals in biogas slurry was within the allowable range,there were potential risks to human health.Children were more likely than adults to suffer from the safety problems associated with biogas slurry farming.This study provided a new idea for the analysis of key parameters of manure fertilizer and provided a theoretical reference for the utilization and promotion of agricultural organic waste fertilizer. |
