Ratoon Rice-Duck Co-Culture Maintains Rice Grain Yield and Decreases Greenhouse Gas Emissions in Central China

Abstract

Both ratoon rice monoculture and rice-duck co-culture systems are gaining growing popularity in China. However, it remains unclear whether integration of ducks into ratoon rice field can reduce the inputs, and how it affects the crop productivity and greenhouse gas emissions amid resource scarcity and climate change. Here, a two-year field experiment was conducted in Hubei Province of central China in 2020 and 2021 to evaluate rice grain yield, global warming potential (GWP), and GWP intensity (GWPi) from both main and ratoon seasons of ratoon rice monoculture system and ratoon rice-duck co-culture system. The four treatments including ratoon rice monoculture system with traditional fertilizer and pesticide management (RR), ratoon rice-duck co-culture system without pesticide application (RRD-P0), ratoon rice-duck co-culture system with reduced pesticide application (RRD-P1), and ratoon rice-duck co-culture system with reduction of both fertilizer and pesticide application (RRD-F1P1) were carried out with three replications under field conditions. On average, the ratoon rice-duck co-culture systems (RRD-P1 and RRD-F1P1) showed significantly lower emissions of CH4 and CO2, and therefore lower GWP than ratoon rice monoculture system (RR). Compared with RR, lonely reducing pesticides by 88.4% (RRD-P1), and reducing fertilizer by 15.0% and pesticides by 88.4% (RRD-F1P1) in ratoon rice-duck co-culture system significantly decreased GWP by 18.7-24.9% and GWPi by 21.6-32.0% without sacrificing rice grain yield on an annual basis while eliminating pesticides application in ratoon rice-duck co-culture (RRD-P0) caused a GWP intensity increase primarily due to rice grain yield reduction. Overall, introducing ducks into ratoon rice field (ratoon rice-duck co-culture system) could decrease the fertilizer and pesticide uses and reduce greenhouse gas emissions, while maintaining rice productivity in ratoon rice production.

Keywords: Ratoon rice-duck co-culture system, Greenhouse gas emissions, global warming potential, Rice grain yield