The Transformation Of Organic Carbon And Nitrogen With Different Regulation Technology During The Livestock Manure Composting Process

With the rapid development of agricultural intensification, a lot of manure is produced which would cause environmental pollution. It is a serious problem that organic waste should be make reasonable use and "harmless", and then it can produce good quality fertilizer. In order to investigate the effect of material ratio, fermentation agent, ventilation on composting process of organic materials via a38-day composting experiment, cow manure, chicken manure and fungus chaff were mixed in two different proportions and each mixed medium was amended with or without fermentation agent, artificial ventilation or natural ventilation. Dynamics of physical indicator (temperature), chemistry indicator (water content, pH, C/N, nitrogen, organic carbon, humic, et al.), biological indicator (germination index) and Infrared Spectroscopy were monitored during composting process. It could provide technical and theoretical support for the composting animal manure and other agricultural waste. The main conclusions are as follows:(1) Throughout the decomposing process, the temperature reached high-temperature phase in2-3days. The treatment of materials ratio of1:1:1can maintain10days in high-temperature phase and then it gradually decreased to a constant. During the composting, pH changed in the range of8.47～9.63, water content showed downward trend, ashes and germination index showed a rising trend. Fermentation agent can enhance pH in the late composting, significantly reduce the water content of materials ratio of5:3:2and increase the ashes content. Materials ratio of1:1:1with fermentation agent can accelerate material to maturity. In29-day, GI was82.76%to reach full maturity.(2) During composting, total organic carbon, water-soluble organic carbon, C/N showed a downward trend, and alkali-soluble organic carbon, FA showed fluctuated downward trend, and organic carbon mineralization rate showed an increasing trend, and H/F showed fluctuated upward trend. Less cow manure in materials was conducive to the mineralization of organic carbon decomposition and fermentation agent can accelerate the degradation rate of organic carbon, enhance the mineralization rate of organic carbon, and reduce C/N rate. At the end of composting, compared with the beginning, total organic carbon fell25.95%, water-soluble organic carbon fell41.85%, alkali-soluble organic carbon fell10.28%, organic carbon mineralization was9.29%and C/N was14.97which fell27.75%. Organic carbon mineralization was9.26%higher than that of without fermentation agent. Organic acids showed a downward trend during composting and at the end of composting acetic acid were not detected and oxalic acid content dropped significantly in all treatments. Fermentation agent promoted the decomposition and transformation of acetic acid and oxalic acid. In late composting, infrared spectra in1020cm-1、1427cm-1bands increased and had sharp peak. It showed that the contents of carbonate and nitrate increased.(3) Throughout the decomposing process, nitrogen of organic materials showed fluctuating rising trend. Fermentation agent, which significant effected the treatment of materials ratio of1:1:1, could reduce the total nitrogen content and increase the nitrogen loss rates. During the composting, ammonium nitrogen content showed upward-downward changes, and nitrate content, which change was not obvious in the earlier stage, increased rapidly in12days in decomposing. Materials ratio of1:1:1with fermentation agent can promote the transformation of ammonium, increase nitrate content in late composting and rapid reduce NH4+-N/NO3--N rate.16days in decomposing, NH4+-N/NO3--N rate was0.15and reach the maturity standards (≤0.16).(4) Compared with natural ventilation, artificial ventilation was in favor of rapid decomposing of organic material, promoting declined C/N rate, accelerating transformation of ammonium, increasing nitrate content in late composting and rapid reducing NH4+-N/NO3--N rate. At the end of decomposing, C/N ratio was11.32%lower than that of natural ventilation.16days in decomposing, NH4+-N/NO3--N rate was0.15and it was4days ealier than that of natural ventilation reach the maturity standards (≤0.16). But artificial ventilation increased nitrogen loss rate, and at the end of composting, nitrogen loss rate was7.03%higher than that of natural ventilation.(5) Compared with natural ventilation, artificial ventilation was in favor of promoting mineralization of organic carbon, increasing mineralization rate, promoting transformation from fulvic acid to humic acid and increasing H/F ratio. At the end of composting, compared with natural ventilation, total organic carbon fell8.87%, water-soluble organic carbon fell38.82%, organic carbon mineralization rate rose9.29%and H/F rate rose9.37%.(6) Compared with natural ventilation, artificial ventilation in the middle phase, infrared spectra in1020cm-1、1427cm-1bands increased and had sharp peak. It showed that the contents of carbonate and nitrate increased. Artificial ventilation could increase germination index (GI) and4days earlier than that of natural ventilation to reach maturity standards.