All living things need water, but compared to their body weight, plants need much more water than people. The amount of water a plant needs every day depends on the type of plant, its age, and its environment. A succulent or drought-tolerant plant, such as a cactus, requires less water than a non-succulent plant, such as an African violet. Mature plants require more water than young plants. A mature plant can lose its weight in water each day through transpiration—the process of exchanging water for carbon dioxide. Strong light, hot temperatures, low humidity, and soil density also affect the amount of water plants use every day. Many people install automatic watering systems to keep their grass green in summer; however, a watering system based on time is not a healthy solution for house plants.
Your challenge is to build a sensor-controlled robot to water a plant based on the moisture level of the soil.
In this project, your challenge is to build a sensor-controlled robot to water a plant based on the moisture level of the soil. Your robot will automatically water the plant when it is too dry and stop watering when the soil is wet. You will use a Vernier Soil Moisture Sensor and a Vernier NXT Sensor Adapter connected to your NXT to test the moisture level of your plant’s soil. The soil will be considered “too dry” when the moisture level is between 0%–20%.
You are strongly encouraged to use the Engineering Design Method when creating your device.
Sensors and Equipment
This project features the following Vernier sensors and equipment.