## 2 Materials and Methods
### Description of the Research Sites
#### 2.1.2 Irrigation Innovation Consortium (IIC)  
This study included data collected from the Colorado State University IIC site during 2020 and 2021. Two maize fields were selected as the primary locations for data collection (Figure 4). This site is located in Fort Collins, CO, USA, at a latitude of 40.5542\({}^{\circ}\) N, a longitude of 105.0038\({}^{\circ}\) W, and an elevation of 1486 m ASL. It has a local climate characterized as a subtropical steppe with cold semiarid tendencies. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Irrigation** & **Growing Season** & **Research Field** & **Irrigation** & **Cumulative Gross** & **Cumulative** \\
**Scheduling** & **Growing Season** & **Research Field** & **Events** & **Irrigation (mm)** & **Rainfall (mm)** \\ \hline \multirow{2}{*}{Fully Irrigated} & 2020 & W & 5 & 472 & 36 \\ \cline{2-6}  & 2021 & E & 4 & 330 & 98 \\ \hline \multirow{2}{*}{Deficit Irrigated} & 2020 & E & 3 & 309 & 36 \\ \cline{2-6}  & 2021 & W & 2 & 176 & 98 \\ \hline \end{tabular}
\end{table} 
Table 1: Cumulative soil wetting events (irrigation and rainfall) at LIRF Fields W and E in 2020 and 2021. Figure 2: Plant variety map at LIRF (Fields W and E) in 2021. Most of the area was occupied by the P0157 AMXT maize variety. The data collection took place in two surface-irrigated (furrow) maize fields during July to September in both 2020 and 2021, as illustrated in Figure 4a. These two fields, designated as Fields F and D, had respective surface areas of 64,750 m\({}^{2}\) and 74,867 m\({}^{2}\). The crop-row orientation in Field F was east-west, while Field D had rows oriented in a north-southeast direction, with rows spaced approximately 0.17 m apart. The soil in both fields had a consistent sandy loam texture throughout the entire maize root zone system, with measured volumetric water content at field capacity (\(\rm{VWC_{FC}}\)), permanent wilting  
Figure 4: RGB (red–green-blue) map of the IIC research fields (**a**) and the maize varieties planted in 2021 (**b**). The study maize fields were Fields F and D. Areas in green are vegetation surfaces. Figure 3: The 2020–2021 LIRF experiment design. point (VWC\({}_{\rm PWP}\)), and saturation (VWC\({}_{\rm SAT}\)) of 0.189, 0.069, and 0.410 m\({}^{3}\)/m\({}^{3}\), respectively. The surface irrigation system employed 40 mm diameter aluminum siphon tubes and delivered water to the fields from the main on-site irrigation canal located between the two research fields. The choice of maize varieties differed between 2020 and 2021. In 2020, G02K39-3120 (Golden Harvest, Minnetonka, MN, USA) was planted on May 13, at an approximate rate of 8 seeds per m\({}^{2}\). For 2021, the NK0243-3120 and NK0314-5122 varieties (Syngenta AG, Basel, Switzerland) were planted in both fields, as indicated in Figure 4b. The seeding date was 13 May 2021, and the planting rate was 8 seeds per m\({}^{2}\). The direction of the irrigation water flow was from east to west in Field F. In the case of Field D, the irrigation water flowed in the furrows from north to southwest. The irrigation events usually took place two to three days after obtaining water from the Sand Dike Lateral Company in Fort Collins, CO, USA. Each irrigation event extended over a duration of 6 to 12 h. The irrigation scheduling was determined based on the FAO-56 methodology [2], which was an integral component of the Water Irrigation Scheduler for Efficient (WISE) Application [1]. The WISE application uses a water balance approach for determining irrigation amounts and timing based on a dual crop coefficient approach for ET\({}_{\rm a}\) estimation from tabularized crop coefficient (K\({}_{\rm c}\)) values, a water stress coefficient (K\({}_{\rm s}\)), and daily alfalfa reference ET (ET\({}_{\rm r}\)) rates. The K\({}_{\rm s}\) value was set to 1 since the maize field was constantly irrigated during the data collection season, and root zone water depletion was assumed to have been kept below allowable water depletion levels.