[Emission of NH₃ and N₂O from Spinach Field Treated with Different Fertilizers]

Agricultural management techniques such as fertilizer or manure application have substantial influence on NH₃ and N₂O emissions and, by understanding this influence, management strategies can be developed to reduce them. An experiment was conducted in a greenhouse at Hunan Agricultural University during 2012 to 2013, to investigate effects of different fertilizers on NH₃ and N₂O emissions. The treatments included control without fertilizer (CK), swine composting fertilizer (SC), stored swine manure fertilizer (SS), and chemical fertilizer (FC). The fluxes of NH₃ and N₂O were collected by venting method and static-chamber method, respectively. The results showed that during the spinach growth season, compared with FC, loss of both NH₃ and N₂O for SC were reduced by 52.9% and 95.12%, respectively(P<0.01). However, loss of NH₃ for SS increased by 24.8%, and loss of N₂O reduced by 48.8% compared with FC. Loss rate of NH₃ were SS (10.97%) > FC (4.19%) > SC(2.74%), and emission coefficient for N₂O were FC(4.50%) > SC(2.21%) > SS(0.60%). Yield and utilization of nitrogen for SC were reduced by 19.61% and 13.20% compared with FC, respectively, but not significantly; and significantly reduced by 27.9% and 40.0% compared with SS, respectively. Loss of gases (NH₃ and N₂O) for SC were 1.83%, which was the lowest, while utilization of nitrogen for SC was 13.20%, similar with FC. Greenhouse temperature was not the critical factor during the spinach planting in winter, but soil water was. Therefore, optimizing manure management could reduce ammonia volatilization and N₂O emission loss without decreasing vegetables production, and the present data indicated that SC would be optimal for better yields with reduced ammonia volatilization and N₂O emission loss.