Rice-crayfish co-culture reduces ammonia volatilization and increases rice nitrogen uptake in central China

In recent years, rice-crayfish co-culture has been widely promoted as a newly emerging farming mode in China. The peripheral trench for crayfish farming and paddy field drainage in this farming mode can alter nitrogen (N) fertilizer deposition and ammonia (NH3) diffusion. However, the effect of the peripheral trench on NH3 volatilization remains unclear. We hypothesized that the peripheral trench under rice-crayfish co-culture (RC) can reduce total NH3 volatilization and enhance rice N uptake. Here, a field experiment was conducted to investigate the effect of different rice farming patterns [RC and rice monoculture (RM)] on NH3 volatilization and rice N uptake during the 2018–2019 rice growing seasons. NH3 volatilization from both the paddy field and the peripheral trench under RC was determined. Compared with RM, RC reduced the mean urease activity by 28.2–29.4% in the paddy field by promoting N fertilizer deposition into the peripheral trench. The decrease in urease activity finally reduced the total NH3 volatilization by 16.1–19.6% from both the paddy field and the peripheral trench. As a special drainage structure, the peripheral trench increased the rice N uptake by 16.7–18.3% under RC compared with that under RM by reducing NH3 volatilization.