Rice-fish co-culture promotes multiple ecosystem services supporting increased yields

Rice-fish co-culture, combining rice cultivation with managed fish populations, has been conducted in southeast Asia for more than 2000 years. This is both an extensive and integrated management system that has significant potential to enhance yield by promoting a range of ecosystem services benefiting soil health and natural pest control in the rice growing period. However, very little is known about the role of earthworms in this process once the crop has been harvested. Here, we conducted a field experiment over two years (2019 and 2021) comparing rice-fish co-culture vs. rice-monoculture (fish free) systems in eastern China. We evaluated rice yield, earthworm populations (supporting nutrient cycling and soil structure), soil quality (including nitrogen, phosphorus, potassium and organic matter), pest abundance and populations of arthropod predators. Results showed that rice-fish co-culture increased earthworm and predator populations, while also improving soil quality and decreasing insect pests. This led to increased yield. We showed that the spill-over effects of earthworms from surrounding paddy field ridges into rice paddy fields benefited soil quality acting to increase rice productivity, but that this acted in combination with other processes such as the activity of fish and increased natural pest control. Our study suggests that rice-fish co-culture farming practices support multiple ecosystem services through improved soil quality, earthworm abundance, arthropod predator natural pest control and rice productivity.