Abstract: Based on an experiment with different duck farming densities, we examined the effects of rice-duck co-culture on rice yield of cultivar Nanjing 46 and nitrogen and phosphorus uptake and utilization, providing theoretical reference for the production practice of rice-duck co-culture. Six treatments including conventional control (CK), releasing of 0 (D0), 75 (D1), 150 (D2), 225 (D3), and 300 (D4) ducks per 1 hm² were set up. The rice yield, biomass, nitrogen and phosphorus uptake and utilization were analyzed. Results showed that: (1) rice-duck co-culture significantly reduced rice yield, mainly due to the decrease in the number of effective panicles in rice. Appropriately increasing the farming density of ducks led to an increasing trend in rice yield, with D3 treatment having the highest rice yield. (2) The co-culture of rice and duck significantly reduced the biological yield of rice, whereas both the biological yield and harvest index of rice increased with appropriately increasing the farming density of ducks. The higher rice yield under D3 treatment was the result of the combined effect of the increase in biological yield and harvest index. (3) Rice-duck co-culture significantly reduced nitrogen content and nitrogen uptake of rice plants. With the increases of duck farming density, nitrogen content and nitrogen uptake of rice plants gradually increased. Rice-duck co-culture could significantly improve the efficiency of nitrogen-based dry matter production and grain production of rice. (4) Rice-duck co-culture significantly improved plant phosphorus concentration. Higher duck farming density could significantly increase the phosphorus uptake of rice plants. Rice-duck co-culture significantly reduced the efficiency of phosphorus-based dry matter production and grain production in rice. (5) Although rice-duck co-culture increased production costs, it ultimately improved economic benefits by increasing output value, and increasing duck farming density can further enhance economic benefits. In summary, rice-duck co-culture with the D3 treatment of 225 ducks per 1 hm² resulted in relatively high rice yield, biological yield, and nitrogen and phosphorus uptake, and thus achieved higher economic benefits.

Key words: rice-duck co-culture, rice, yield, nitrogen uptake and utilization, phosphorus uptake and utilization