Impact of sorbent application on NH3 and CO2 and CH4 gas emissions from dairy cattle manure

Abstract

Livestock manure storage is a significant source of gas emissions. Application of various manure additives is one of possible ways to reduce gas emissions. Therefore, this study was conducted to evaluate the effectiveness of sorbents for NH3, CO2 and CH4 emissions from dairy cattle manure. The study was carried out on laboratory scale, using 90-litter tanks. Three treatments, including biochar, peat and dolomite were applied to stored fresh cow liquid manure. The manure was stored for 42 days under a constant ambient temperature of 14°C and 60-62% relative humidity. The emission reductions were evaluated by the treatments as compared to the control group without sorbents. The results of the study showed that average NH3 emission without using sorbents during all study period was 9.2±1.6 mg/m2/h, using biochar - 8.7±1.4 mg/m2/h, peat 9.3±21.7 mg/m2/h, and dolomite 9.1±1.5 mg/m2/h. The addition of biochar reduced NH3 emissions from manure by 5.9%, dolomite - by 0.6%, however, peat increased the emission by 0.8%. The highest average CO2 emission was fixed from manure with dolomite treatment - 155.1±8.2 mg/m2/h, and the lowest from biochar treatment - 120.5±8.0 mg/m2/h, (P=0.03). CO2 emissions from manure without sorbents and manure with peat were 133.1±8.2 mg/m2/h and 147.5±9.8 mg/m2/h, respectively. It was found that the highest emissions value in all groups were observed in the first week, then they gradually decreased and at the end of the study were negligible and the differences between the various treatments were the most insignificant. The highest positive correlation (0.973) between NH3 and CO2 emissions was determined for manure treated with dolomite. Sorbents reduces CH4 emissions from manure on average by 33.6%. In summary, it can be concluded that sorbents most efficiently reduced gas emissions in the first week after adding the sorbents to manure, then this effect decreased. The most effective emission reduction was achieved using biochar. However, at the same time, it can be stated that the ability of sorbents to reduce gas emissions from liquid cow manure is not high, perhaps due to the specific property of cattle manure to for a natural crust during storage.