BackgroundTo maintain rice production and increase revenue, rice‐duck (RD) farming is a contemporary ecological cycle technology that has been widely used in Asia. However, due to the clustering activity of duck flocks, the consequences of long‐term rice‐duck farming on rice growth at different scales are still unknown. Here, we studied rice‐duck farming at several different treatments (CK: conventional rice farming, RD1: 667 m2, RD2: 2000 m2, and RD3: 3333 m2).ResultsThe results demonstrated that the maximum tillers, effective spikes, dry matter accumulation and lodging index of rice under rice‐duck farming were significantly decreased by 17.9%, 9.8%, 14.8%, and 17.8%, respectively, which ultimately caused a significant decrease in yield of 10.6%. However, rice‐duck farming significantly increased root oxidation activity and the earbearing tiller rate of rice by 25.5% and 11.1%, respectively, and improved yield stability. For different scales of rice‐duck farming, the lodging resistance index of RD1 was significantly lower than that of RD2 and RD3 by 10.0% and 15.2%, respectively, whereas the root oxidation activity and dry matter accumulation of RD2 were significantly higher than those of RD1 and RD3 by 11.1%, 4.7%, 8.6% and 5.1%, respectively. For rice yield, there was no significant difference among the different scales.ConclusionThis long‐term experiment helped elucidate the complicated effects of rice‐duck farming at different scales on the growth and yield of rice. It is also critical to consider the economic advantages of different scales of rice‐duck farming to assess the impact of this system more thoroughly.This article is protected by copyright. All rights reserved.