## 3 Results  
### Response of the Automated Irrigation Scheduling  
Different water stress treatments began on 4 April 2019 (176 DAP). According to the subsequent irrigation strategies, T1 was irrigated automatically on 176 DAP, 187 DAP, 192 DAP, 203 DAP, 207 DAP, 209 DAP, 212 DAP and 215 DAP, with a total irrigation amount of 1.8 m\({}^{3}\), while T4 was irrigated only once on 11 May, with an irrigation amount of only 0.2 m\({}^{3}\). T2 and T3 were irrigated four times and three times, respectively, with irrigation amounts of 1.1 m\({}^{3}\) and 0.7 m\({}^{3}\), respectively. Compared with T1, the irrigation amounts of T2, T3 and T4 decreased by 18.18%, 28.57% and 41.56%, respectively. The irrigation times and irrigation amounts of experimental plots under different water stresses are shown in Table 2.  
Since the roots of winter wheat were densely distributed at 0-50 cm, the soil moisture in this study was represented by the average soil moisture at depths of 10, 20 and 50 cm. Before the water stress treatments, the soil moisture values of each plot were similar. When the irrigation strategies of each plot were establishing using an IICS based on the IoT, automatic irrigation was implemented, and the soil moisture of each plot showed varied trends. On 176 DAP, as the soil moisture of plots T1 and T2 reached the lower threshold of irrigation conditions, the IICS irrigated the two plots and their soil moisture increased. The soil moisture of plots T3 and T4 plots had not yet reached the threshold for irrigation conditions, so their soil moisture continued to decline, and irrigation was not initialized until the threshold of irrigation conditions was reached. We can know that the soil moisture of T1 fluctuated more frequently (Figure 6). This was because the threshold of the soil moisture for irrigation conditions must be set high to achieve a drought-free state, more irrigation events are triggered. However, T4 was set to receive the severe water stress treatment, and the threshold of the soil moisture for irrigation conditions was set very low; therefore, only one irrigation was carried out on 213 DAP. In the other cases, the fluctuations in the soil moisture values were caused by precipitation. After receiving the water stress treatment, the soil moisture of each plot was maintained under user-defined conditions, expressed as T1 > T2 > T3 > T4, which showed that the IICS was able to realize automatic irrigation and control the soil moisture at an ideal level (Figure 7). \begin{table}
\begin{tabular}{c c c} \hline \hline
**Plot** & **No. of Irrigations** & **Irrigation Amount (m\({}^{3}\))** \\ \hline T1 & 9 & 3.85 \\ T2 & 6 & 3.15 \\ T3 & 4 & 2.75 \\ T4 & 3 & 2.25 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Irrigation times and irrigation amounts of experimental plots under different water stresses. Figure 6: Seasonal variation of soil moisture under different water stresses. The soil moisture was represented by the average soil moisture at depths of 10, 20 and 50 cm. DAP means days after planting. In this study, the T1 plot was selected to explore the variation characteristics of soil moisture in different layers. The trends of soil moisture values at 10 cm and 20 cm were similar, and their fluctuations were relatively severe (Figure 8). The soil moisture changes observed at 50 cm and 80 cm were relatively gentle. This was because the soil sensors at 10 cm and 20 cm were close to the ground surface and were greatly affected by irrigation. The soil moisture at 20 cm was the highest value observed, because it was greatly affected by irrigation and was less affected by evapotranspiration. The soil moisture at 50 cm was the lowest and was even lower than that at 80 cm. This was because, although the soil moisture values at 50 cm and 80 cm were not greatly affected by irrigation, the soil moisture at 80 cm was less affected by evapotranspiration. Figure 8: Seasonal variation of soil moisture at different depths in T1. DAP means days after planting.