Evaluation and analysis of comprehensive benefits of aquaponics technology in Jiangning District, Nanjing City

Objective Aquaponics technology combines the advantages of aquaculture and crop cultivation, featuring high nitrogen conversion utilization ratio as well as water saving and emission reduction, realizing a win-win situation for both economic and environmental benefits, but aquaponics system involves many economic and environmental indicators, and there are fewer current studies on comprehensive benefit evaluation of this production model. In this study, the environmental and economic benefits of aquaponics systems were quantitatively analyzed, systematically evaluated and compared, with a view to providing new ideas for qualitative and quantitative analyses and research on aquaponics technology.

Method Based on the actual construction and operation data of the aquaponics farm in Jiangning District, Nanjing City, this study took environmental and economic benefits as two main evaluation indexes, calculated nitrogen emission of the single aquaculture mode as well as related nitrogen loss and nitrogen transformation in the aquaponics through the empirical formula method, qualitatively and quantitatively calculated nitrogen transformation and emission of the aquaponics system through the measurement method, and calculated the economic indexes of the aquaponics system based on the questionnaire of the farm and the results of the research.

Result After adopting aquaponics technology, the total nitrogen emission was reduced by 99.45% and the total ammonia nitrogen emission was reduced by 99.73% compared with the single aquaculture mode; N₂O emission and microbial assimilation caused more nitrogen loss, were 4.58 and 48.60 times more than total nitrogen emission in water, respectively; The degradation of NO₂⁻−N by nitrifying bacteria was enhanced, the water quality was more conducive to the survival of fish. In the first year of aquaponics farm, the construction cost accounted for 55.21%, which exceeded the sum of other expenditures. Feed cost was the main source of cost when running the aquaponics farm, accounting for 73.96%. Aquaculture income accounted for 89.74% of the total income, which was 8.75 times more than the sum of planting income and service income.

Conclusion This study establishes the scientific comprehensive benefit evaluation system of aquaponics, which has certain guiding significance for the evaluation of ecological and economic benefits of aquaponics technology, and can provide multi-dimensional references for the research and application of aquaponics technology.