牛粪堆肥方式对温室气体和氨气排放的影响

为明确堆肥过程中温室气体和氨气排放规律以及产生的总温室效应,在云南省大理州开展堆肥试验,并以奶牛粪便为试验材料,研究了农民堆肥(FC)、覆盖堆肥(CC)、覆盖-翻堆堆肥(CTC)和覆盖通风-翻堆堆肥(CATC)4种堆肥方式对温室气体和氨气排放的影响。结果表明:覆盖通风-翻堆堆肥(CATC)可提高堆肥腐熟度,有效降低CH4和N_2O排放,但并没降低CO2和NH_3排放;与农民堆肥(FC)相比,覆盖堆肥(CC)的CH4排放量增加了48.7%,而N2_O和NH3排放量与农民堆肥(FC)基本一致;覆盖-翻堆堆肥(CTC)虽然提高了腐熟度,但CH_4、CO_2和NH_3排放量较大;堆肥结束时,4个处理的总温室效应分别为25.6、32.9、38.1及18.0 kg/t;温度与CH_4、CO_2、N_2O和NH_3排放速率均极显著相关,pH值显著影响N_2O和NH_3的排放。因此,覆盖通风-翻堆堆肥(CATC)不仅能够满足堆肥产品的腐熟度要求,而且能够减少总温室效应,再加上其操作简便,能够在生产中推广应用。

Effects of cattle manure composting methods on greenhouse gas and ammonia emissions

Composting is an environmentally friendly technology for treating livestock manure by transforming organic matter into more stable and nutritional fertilizer. However, composting is also a significant source of CH4, CO2, N2O and NH3 gases if proper composting methods are not used. The production of these gases not only reduces the agricultural value of the final compost but also aggravates some environmental problems such as global warming, which reduces the environmental benefits of composting. Four types of composting methods are used extensively, namely farmer compost (FC), covering compost (CC), covering-turning compost (CTC) and covering and aeration-turning compost (CATC). Concerns about climate change have increased the demand for strategies to minimize greenhouse gas and ammonia emissions. However, the greenhouse gas and ammonia emissions from the 4 composting methods during composting have received little attention. The purpose of this study was to analyze the greenhouse gas and ammonia emissions from the composting of dairy manure with these 4 types of composting methods. These results will assist the identification of better composting methods with the potential to mitigate greenhouse gas and ammonia emissions. The evolution of CH4, CO2, N2O and NH3 and maturity index were monitored in 4 composting mixtures in Dali Prefecture, Yunnan Province. Gas samples were taken at various stages of composting from December 2015 to February 2016, and the period was over 64 days. The results showed that the CATC resulted in the most desirable maturity, and effectively reduced CH4 and N2O emissions. However, this composting method did not reduce CO2 and NH3 emissions from the cumulative gaseous emissions. Under the CC conditions, CH4 emissions increased by 48.7% compared with the FC; however, N2O and NH3 emissions from the CC were similar to the FC, which resulted from covering with a plastic film. Although the CTC improved the maturity of the final compost, this method was also featured with the increased emissions of CH4, CO2, and NH3. Throughout the study period, the CATC released the lowest amount of total greenhouse gas (CH4 and N2O) (18.0 kg/t), followed by the FC (25.6 kg/t), CC (32.9 kg/t), and CTC (38.1 kg/t). The total greenhouse gas (CH4 and N2O) emissions of the CC and CTC were 1.8 and 2.1 times as high as that of CATC at the time of maturity, respectively. The greenhouse gas and ammonia emissions varied substantially with time and were significantly correlated with temperature. The pH values of the compost could significantly affect the emissions of N2O and NH3, which indicated a potential way to mitigate greenhouse gas and ammonia emissions through proper compost management. Compared with other composting methods, the CATC showed the greatest potential to mitigate the overall greenhouse effect, and a greater maturity than the other 3 composting methods. Moreover, the lower cost and operational convenience of CATC could allow this method to be easily put into practice. Among the 4 composting methods, covering and aeration-turning compost (CATC) is considered to be a superior composting method, which should be promoted among farmers.