N and C transformations in stored cattle farmyard manure, including direct estimates of N2 emission

Nitrogen and carbon dynamics during the storage of cattle farmyard manure (FYM) throughout 52 days were evaluated in terms of mass balance, considering solid, liquid and gaseous components. The objectives were: (i) to quantify NH3, N2O, CO2 and CH4 emissions to supplement existing empirical evidence; (ii) to improve our understanding of the N and C transformations and the main factors that control these processes; and (iii) to provide the first measurement-based estimates of N2 emissions from stored cattle FYM. Approximately 1.5% of the initial total N was emitted as NH3 and 1.0% as N2O. Losses of N2 via denitrification were estimated to be greater than N losses via NH3 and N2O, at 5.2% of initial total N. The main C loss was as CO2, accounting for ca. 10% of the initial total C content, with CH4 emissions accounting for <1%. Heap temperature and rainfall strongly influenced gaseous emissions from this type of storage.

► Heap temperature and rainfall strongly influenced gaseous emissions in FYM storage. ► Total denitrification losses were greater than measured NH3 emissions. ► Approximately 1.5% of the total initial N was emitted as NH3–N, 1.0% as N2O and 5.2 as N2. ► CO2 represented the main C losses with ca. 10% of the total initial heap C content.