Study On Transformation Of Carbon And Nitrogen As Well As Greenhouse Gas Emission During Pig Breeding Litter Combine With Mushroom Residue Composting

With the development of science and technology, agricultural industrialization is significantly improved. However, the amount of some agricultural waste such as livestock manure and mushroom residue, also have a significant rise. Casually discard untreated agricultural wastes not only lead to a waste of resources, but also pose a grave threat to the environment. Thermophilic aerobic composting is an effective way to turn waste into wealth. However, during composting process, there is always company with carbon and nitrogen loss, greenhouse gas emission and other problems. Thermophilic composting process is carbon and nitrogen cycling process substantially, which is microorganisms involved,thus it is the basis for reduce carbon,nitrogen loss and greenhouse gas emission to study on the rules of carbon and nitrogen transformation as well as the interaction between microbial during thermophilic aerobic composting, Meanwhile, the research has important theoretical value and practical significance for the development of the theory and technology of composting, improving the quality of compost product and raising the utilization ratio of agricultural wastes.In this paper, the waste padding of Pig-breeding fermentation bed and mushroom dreg were used as raw materials to conduct high temperature compost test in the self-made forced-ventilation static composting reaction tank. The main aim of the research was to find the effects of different proportion of padding materials and mushroom dreg as well as adding EM agents on compost composting process and carbon and nitrogen transformation process. The main conclusions are as follows:1.That the mushroom dreg-based treatment temperature is higher than 50 ℃ for more than a week meets the standards of being harmless, and EC values of the mushroom dreg-based treatment were 2.28 and 2.32, which will bring no toxic effects on the crop. The EC values of padding-based treatment were 4.545 and 5.655. But the portion of total phosphorus and total potassium in padding-based treatment was higher than that in the mushroom dreg-based treatment. The GI values of four treatment were up to more than 80 percent. Overall, adding EM agents can significantly shorten the composting cycle, but did not show advantage on the accumulation of nutritive elements of putrescibility. Generally, the accumulation of putrescibility and nutritive elements of padding-based treatment is higher than that of mushroom dreg-based treatment.2.The nitrogen fixation capacity of padding-based compost ratio, T1 and T3, was higher than T2 and T4, mushroom dreg-based treatment compost ratio. The mushroom dreg-based treatment, after adding EM agents, was more conducive to maintaining nitrogen in composting process.3.In this experiment, the carbon loss mostly happened in cooling period. The portion of organic carbon and soluble carbon in treatment that was added in EM agents was less than the treatment without them. Padding-based treatment was more conducive to improving the quality of humus than mushroom dreg-based treatment and treatment added in fungicide was more conducive to the formation of humic substances and improvement of maturity than the treatment without fungicide..4.The amounts of PLFAs biomarkers contents of adding EM agents treatments were higher than the treatment without them, while similarly add EM agents processing, the amounts of microorganism of the mushroom dreg-based treatment was higher than that of padding-based treatment, the variety of microbial species of the mushroom dreg-based treatment, T2 and T4, were higher than that of padding-based treatment, T1 and T3. The biological marker values of composting dealing with PLFAs were from largest to smallest as bacteria, fungi, actinomycetes, aerobic bacteria, methane-oxidizing bacteria and protists. The diversity index of the composting treatments with EM agents, T3 and T4, was higher than that of T1 and T4 treatments, as well as diversity indexes of the mushroom dreg-based T4 treatment were all higher than that of the mushroom dreg-based treatment,T3.5.Among greenhouse gases CO2, CH4 and N2O the one with highest emission rate was CO2, followed by N2O, and CH4. Prophase had the highest emission rate for early and the emission load decreases gradually. For the greenhouse gas emission rates, the peak time of T1, T2 treatment (without fungicide) was between 11:30 and 12:30 as well as 17:30 and 18:00; T3 and T4 (with fungicide) had their peak value in between 8:30 and 9: 00 as well as 17:00 and 18:00. The 2nd peak exists in between 8:30 and 9:00 as well as between 14:30 and 15: 00. For the N2O emission rate between first and secondary fermentation, the peak time occurred between 8:30 and 9:00 am and 20:30-21:00. The daily emission rate of padding-based treatment was higher than that of mushroom dreg-based treatment. Mushroom dreg-based treatment with fungicide helps reduce greenhouse gas emissions.6.Temperature was significantly and positively correlated with CO2 and CH4, correlation coefficient respectively was 0.34 and 0.41. Moisture was proportional to greenhouse gas emission, higher moisture contents and higher greenhouse gas emissions, especially moisture had largest impact on N2O. In addition, total nitrogen, microbial biomass carbon and microbial biomass nitrogen were significantly and negatively correlated with CO2; fungi, bacteria, actinomycetes were significantly and positively correlated with CO2 emission, especially the influence of bacteria was the largest. Total phosphorus, organic nitrogen and the value of HI were significantly and positively correlated with CH4, whereas C/N ratio and humic acid were significantly and negatively correlated with CH4. EC value, ammonium nitrogen, nitrate nitrogen and soluble organic carbon were significantly and positively correlated with N2O emission, while humic acid and HI ratio were in inverse proportion to it, correlation coefficient respectively was 0.55 and 0.49; microbial biomass carbon was negatively correlated with N2O; fungi, bacteria, methane-oxidizing bacteria were significantly and positively correlated with N2O, and the influence of bacteria was the largest.7.Comparing the quality of composting product, carbon and nitrogen loss, greenhouse gas emission of four compost treatments, the overall effect of the T3 and T4 with inoculants were better than the overall effect of the T1 and T2, while the overall effect of T4 was the best of the four treatments’overall effects.