Figure 1:
The red circle inside Thailand map indicates Nakhon Si Thammarat Province (left-hand side), and another red circle inside the Nakhon Si Thammarat Province map indicates Pak Phanang District (right-hand side).
Figure 2:
The development stage of the IoT-based smart watering system.
Figure 3:
The demonstration of the installation pump system and solenoid valves.
Figure 4:
The process of automatically “on and off” system of water pump and solenoid valves by using the application Blynk.
Figure 5:
The schematic diagram of the electronic circuit in the control cabinet. VDC refers to Voltage Direct Current.
Figure 6:
The equipment installed inside the control cabinet.
Table 1:
Electronics used to develop the smart watering system
| Electronics used | Description |
|---|---|
| Microcontroller | NodeMCU ESP32 |
| Soil moisture sensor | Modbus RTU RS485 |
| Temperature sensor | DHT22 Module |
| Power supply | Transformer |
| Smartphone and operating system | Xiaomi and Android |
| Relay | Relay Module |
| Magnetic contactor | S-N20 Coil AC24V |
| Circuit breaker | Safety breaker AC240V 30A |
| AC/DC converters | Bridge rectifier diode and capacitor |
| DC to DC converters step-down | ET-MINI PWR12-3A |
Figure 7:
The installation of soil moisture sensors under pomelo trees.
Figure 8:
Water sprinkler at the bottom of a pomelo tree.
Table 2:
Components used in the conventional and smart watering systems
| Components used | Conventional watering system | Smart watering system |
|---|---|---|
| IoT-based smart watering system | No | Yes |
| Soil moisture sensing system | Yes | Yes |
| Watering method | Water sprinkler at the bottom of each tree. Farmers turn on the pump and water valve manually. | Water sprinkler at the bottom of each tree. Farmers can set time and control water pumps and valves automatically by using their smart phones. |
| Watering time/day | 8.00 a.m. to 8.30 a.m. and 13.00 p.m. to 13.30 p.m. | 6.30 a.m. to 6.45 a.m., 9.30 a.m. to 9.45 a.m., 12.30 p.m. to 12.45 p.m., and 3.30 p.m. to 3.45 p.m. |
| Watering duration/tree/day | 60 min | 60 min |
| Water amount/tree/day | 200 L | 200 L |
Figure 9:
The complete process of smart watering system for monitoring and increasing soil moisture content in pomelo garden.
Figure 10:
Soil moisture (%) trend lines in the conventional and smart watering systems.
Figure 11:
Soil moisture (%) differences in the conventional and smart watering systems.
Figure 12:
The relationships between air temperature (°C) and soil moisture (%) in the conventional and smart watering systems.
Table 3:
The performance of some existing smart watering systems
| Existing watering systems | Performance | References |
|---|---|---|
| Sensor-based smart irrigation networks system for efficient irrigation and water savings | A sensor-based smart irrigation networks system was successfully used to monitor and maintain soil moisture and water consumption in strawberry greenhouses in Greece. | [34] |
| Sensor-based smart irrigation systems to monitor soil moisture and maintain irrigation process | A sensor-based smart irrigation system was used successfully to monitor real-time soil moisture and maintain the irrigation process to save water in tomato greenhouses in China. | [35] |
| An IoT-based smart watering system to increase moisture (%) content | An IoT-based smart watering system was used successfully to increase the moisture (%) content inside the mangosteen canopy in Thailand. | [37] |
| An IoT-based smart watering system to reduce thrips numbers | An IoT-based smart watering system was used successfully to reduce the thrips numbers in mangosteen orchards in Thailand. | [38] |
| Sensor-based irrigation system to control irrigation-related parameters | A sensor-based irrigation system was used successfully to measure and control temperature and humidity in melon orchards in Thailand. | [50] |
| Sensor-based automatic watering system to monitor and maintain the required level of soil moisture | A sensor-based automatic plant watering system was used successfully to monitor air temperature and soil humidity as well as to maintain required levels of soil moisture in eggplant farm in Indonesia. | [56] |