## 2 Materials and Methods
### Eddy Covariance and Meteorological Measurements  
The key instruments of the EC system at ST1 consisted of a fast-response 3D sonic anemometer (R3-50, Gill Instruments, Inc., Hampshire, UK), an open-path CH\({}_{4}\) gas analyzer (LI-7700A, Li-COR Biosciences, Inc., Lincoln, NE 68504, USA), an open-path CO\({}_{2}\)/H\({}_{2}\)O gas analyzer (LI-7500A, Li-COR Biosciences, Inc., Lincoln, NE 68504, USA), and a data logger (LI-7500, Li-COR Biosciences, Inc., Lincoln, NE 68504, USA) to record raw data from the open-path EC system. For ST2, the CO\({}_{2}\)/H\({}_{2}\)O and CH\({}_{4}\) gas analyzers and data logger were the same as those for ST1, and a WindMaster Pro (Gill Instruments Inc., Hampshire, UK) was used to measure the wind speed in all 3 dimensions. All the sensors at the 2 sites were installed at a height of 2.5 m above ground level.  
The meteorological sensors at each site included a combined humidity and temperature sensor (HMP155, Vaisala, Inc., Helsinki, Finland), a net radiometer (NR Lite 2, Kipp & Zonen, Inc., Delft, Holland) and a photosynthetically active radiation (PAR) sensor (LI-190 SB, Li-COR Biosciences, Inc., Lincoln, NE 68504, USA) installed at a height of 3 m; 3 soil heat flux plates (HFP01, Hukseflux, Inc., Delft, Holland) buried at a depth of 5 cm; 3 combined soil moisture and temperature sensors (ML2x, Delta-T Devices, Inc., Cambridge, UK); and a tipping bucket rain gauge (TR-525M, Texas Electronics, Inc., Dallas, TX 75237, USA).  
\begin{table}
\begin{tabular}{c c c c c c} \hline  & **Growth Stage** & \multicolumn{2}{c}{**Field Management**} & \multicolumn{2}{c}{**Fertilizer Application**} \\ \hline Vegetative stage & 27 July–25 August & \multicolumn{2}{c}{Field ponding} & 20 July & \multicolumn{2}{c}{Basal fertilizer} & 26 July \\ Reproductive stage & 26 August–6 October & Transplanting & 26 July & \multicolumn{2}{c}{Tiltering fertilizer} & 2 August \\ Ripening stage\({}^{a}\) & 7 October–31 October & Mid-season drainage & 21 August–25 August & \multicolumn{2}{c}{Particle fertilizer} & 28 August \\  & & Harvest & \multicolumn{2}{c}{November} & \\  & & 2019–late rice–ST2 (WT \({}^{*}\): local farms’ traditional irrigation method) & \multicolumn{2}{c}{} \\ Vegetative stage & 12 July–30 August & \multicolumn{2}{c}{Field ponding} & 6 July & \multicolumn{2}{c}{Basal fertilizer} & 11 July \\ Reproductive stage & 31 August–2 October & \multicolumn{2}{c}{Seeding} & 10 July & \multicolumn{2}{c}{Tiltering fertilizer} & 20 August \\ Ripening stage & 3 October–14 November & Mid-season drainage & 26 August–30 August & \multicolumn{2}{c}{} \\ Fallow season & 15 November–10 March & \multicolumn{2}{c}{Harvest} & \multicolumn{2}{c}{15 November} & \\  & 2020–merly rice–ST2 (WT \({}^{*}\): local farms’ traditional irrigation method) & \multicolumn{2}{c}{} \\ Vegetative stage & 24 March–13 May & \multicolumn{2}{c}{Field ponding} & 20 March & \multicolumn{2}{c}{Basal fertilizer} & 24 March \\ Reproductive stage & 14 May–16 Jun & \multicolumn{2}{c}{Seeding} & 23 March & \multicolumn{2}{c}{Tiltering fertilizer} & 1 May \\ Ripening stage & 17 June–11 July & Mid-season drainage & 8 May–13 May & \multicolumn{2}{c}{} \\  & & 2020–late rice–ST2 (WT \({}^{*}\): local farms’ traditional irrigation method) & \multicolumn{2}{c}{} \\ Vegetative stage & 12 July–7 September & \multicolumn{2}{c}{Field ponding} & 6 July & \multicolumn{2}{c}{Basal fertilizer} & 12 July \\ Reproductive stage & 8 September–10 October & \multicolumn{2}{c}{Seeding} & 10 July & \multicolumn{2}{c}{Tiltering fertilizer} & 19 August \\ Ripening stage & 11 October–20 November & Mid-season drainage & 28 August–7 September & \multicolumn{2}{c}{21 November} & \\  & & Harvest & \multicolumn{2}{c}{} \\ \hline \end{tabular} \({}^{a}\) WT: water management.  
\end{table}
Table 1: Crop management for ST1 and ST2.