# Irrigation System for a Roller-Type Onion Pot Seeding Machine
## 2 Materials and Methods
### Specifications of the Irrigation System Developed  
The irrigation system developed here is a drip-type, and the schematic is shown in Figure 2. The main components are the water tank, water pump, pressure gauge, irrigation pipe, irrigation height regulator, and hand valve. Their characteristics and functions are as follows:  
A. Water tank: this stores the water to be used for irrigation. Water can be filled continuously through a water supply hose, using a float valve system, or it can be used as a storage tank without the water supply hose (Figure 3). The storage capacity is 50 liters. A transparent container was utilized to check the level of remaining water in the tank. B. Water pump: the water stored in the water tank is circulated by the water pump to transport it to the irrigation pipe. A filter at the inlet of the water pump prevents foreign substances from entering the irrigation pipe. The capacity of the water pump was determined by preliminary experiment, to ensure a sufficient flow rate. The specifications of the water pump are provided in Table 2. \begin{table}
\begin{tabular}{c c} \hline \hline
**Classification** & **Contents** \\ \hline Model/Manufacturer/Nation & UP300/Hyubshin Water Design/Korea \\ Rated voltage & 30 W \\ Maximum discharge & 18 L/min \\ Displacement & 1080 L/h \\ Gross pump head & 2600 mm \\ Length \(\times\) Width \(\times\) Height & \(89\times 112\times 98\) mm \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Specifications of the water pump. Figure 2: Schematic of the developed irrigation system. C. Pressure gauge: this is installed between the water pump and irrigation pipe inlet to measure the pressure of water entering the irrigation pipe. Its measurement range was selected by preliminary experiment to cover the actual pressure range. The specifications of the pressure gauge are listed in Table 3.  
D. Irrigation pipe: this is the part that performs watering on the crops. Two identical irrigation pipes with an inner diameter of 12 mm are aligned for two times watering. Each irrigation pipe has 14 irrigation holes in a row, and the location of each irrigation hole coincides with the position of each pot tray cell, allowing watering by individual cells. The positions of irrigation holes and a picture of the irrigation pipes are shown in Figure 4.  
Figure 4: A view of the irrigation pipe: (**a**) position of the irrigation holes; (**b**) picture of the irrigation pipe. Figure 3: Picture of the water tank. \begin{table}
\begin{tabular}{c c} \hline \hline
**Classification** & **Contents** \\ \hline Model/Manufacturer/Nation & SS-3011/Konics/Korea \\ Accuracy & \(\pm\)1.5\% \\ Measurement range & 0–1 bar \\ Applicable temperature & 20–40 \({}^{\circ}\)C \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Specifications of the pressure gauge. E. Irrigation height regulator: this is used to regulate the height of the irrigation pipe. The irrigation pipe is mounted on the upper end of the height regulator. The height regulator is attached to the side frame of the roller-type onion pot-seeding machine, and the height can be adjusted through the sliding hole and bolted connection. Its height is controllable up to 150 mm from the top of the pot tray, and its schematic is shown in Figure 5.  
F. Hand valve: this component is used to control the flow rate of water by varying the water pressure of the irrigation pipe. It is installed between the irrigation pipe outlet and bypass pipe. The water pressure and flow rate increase when the hand valve is opened, and decrease when the valve is closed. The shape and specifications are shown in Figure 6 and Table 4,  
The operation procedure of the irrigation system is as follows: the water stored in the water tank moves to the irrigation pipe using the water pump, and is supplied to each cell of the pot tray by dropping through the irrigation holes. The residual water after irrigation returns to the water tank through the bypass pipe. The water pressure and flow rate are regulated by the hand valve.