The dynamics of nitrous oxide and methane emissions from various types of dairy manure at smallholder dairy farms as affected by storage periods.

Storing manure emits greenhouse gas (GHG) emissions, including nitrous oxide (NO) and methane (CH). However, the emissions from types of manure stored at smallholder dairy farms remains unknown. Hence, the study aims to analyse the dynamics of NO and CH from different types of dairy manure as affected by storage periods. We collected samples from fresh manure (FM-DF1), manure from communal ponds in an urban dairy farm (IP-DF1, FP-DF1, MS-DF1), fresh manure from an urban dairy farm (FM-DF2), and fresh (FM-DF3), separated (FS-DF3), and fermented manure (FR-DF3) from a peri-urban dairy farm, and stored them for eight weeks and analyse them using the closed chamber method. The changes of manure composition including total solids (TS), nitrogen (N), ammonia-nitrogen (N-NH), and carbon (C) were analysed. Results indicated an increase TS in all treatments except for MS-DF1, while N, N-NH, and C content decreased in all treatments. The NO emissions formed at the start, peaked in the middle, and declined towards the end storage period. The CH emissions peaked at the start and decreased until the end storage period. Treatment FM-DF2 yield highest cumulative of NO (0.82 g/m) and CH (41.63 g/m) compared to other fresh manure treatment. A mixed model analysis detected a significant interaction (p < 0.05) between manure types and storage periods. In conclusion, manure types and storage periods affect the emissions. Changes in manure concentration during storage and animal diets are two important factors influencing emissions. Strategies to reduce emissions include reducing moisture content in manure, shortening storage periods, and improving feed quality.