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| Impacts of different crop-fish co-culture systems on N2O emission from freshwater aquaculture systems |
| Received:November 26, 2020 |
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| KeyWord:crop-fish co-culture systems;N2O emission characteristics;functional genes;nitrogen pollution |
| Author Name | Affiliation | E-mail | | BAO Ting | China National Rice Research Institute, Hangzhou 311400, China | | | WANG Meng-jie | China National Rice Research Institute, Hangzhou 311400, China | | | WU Jun-nan | China National Rice Research Institute, Hangzhou 311400, China | | | LIU Yao-bin | China National Rice Research Institute, Hangzhou 311400, China | | | LI Feng-bo | China National Rice Research Institute, Hangzhou 311400, China | | | FENG Jin-fei | China National Rice Research Institute, Hangzhou 311400, China | | | FANG Fu-ping | China National Rice Research Institute, Hangzhou 311400, China | fangfuping@caas.cn |
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| Abstract: |
| A pot experiment was conducted to elucidate the impacts of crop（Oryza sativa L. subsp. japonica Kato, Oryza sativa L. subsp. sativa, Brassica rapa L. ssp.pekinensis or Ipomoea aquatic Forsk）and yellow catfish（Pelteobagrus fulvidraco）co-culture on the production and emission of N2O from a freshwater aquaculture system. Net N2O flux and concentration in the overlying and soil pore water of different treatments were measured using static chamber and headspace equilibrium-gas chromatography methods. Co-culture of crop and fish significantly reduced N2O emission from the aquaculture system. The total amount of N2O emissions from the indica rice-fish co-culture, japonica rice-fish co-culture, water spinach-fish co-culture, and little cabbage-fish co-culture systems were reduced by 82.1%, 69.2%, 67.9%, and 60.3%, respectively, compared with the fish monoculture system. Rice-fish co-cultures reduced N2O concentration both in the overlying and soil pore water, while the vegetable-fish co-culture only reduced N2O concentration in the overlying water. The rice-fish cocultures significantly reduced the concentrations of total nitrogen（TN）, NH4+-N, and NO3--N in the aquaculture water and concentrations of NH4+-N and DON in soil. The vegetables-fish co-culture significantly reduced the concentration of NO3--N in aquaculture water. Crop-fish co-cultures significantly increased the abundance of nirK and nosZ genes in the soil at the early co-culture stage but did not significantly affect the abundance of nirS genes at the full co-culture stage when compared with the fish monoculture. The crop-fish co-culture had no significant effect on fish yield but significantly improved the system's nitrogen nutrient utilization, reducing N2O emissions from the aquaculture system. The mitigation effect of the indica rice-fish co-culture system was better than the other three co-culture systems. |
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