Time to Water?
A Study Using the Soil Moisture Sensor
Here's an idea for an experiment with the new Vernier Soil Moisture Sensor. We wondered how much influence drainage holes had on soil moisture when a house plant is watered. Our setup consisted of two 2 L soda bottles with the bottoms removed. A hole was cut in the side of each bottle to accommodate the Soil Moisture Sensor, and the opening was sealed with tape after insertion. The bottles were then placed neck down into two 1 L beakers.
One bottle had the cap removed to facilitate drainage, while the other was left on. A piece of screen was placed in the neck of each bottle to prevent the soil from falling out of the bottom. Equal amounts of soil were added to each bottle and the Soil Moisture Sensors were inserted. Data collection was started, one sample per hour for 80 hours, then equal amounts of water were added to the bottles.
As the graph indicates, it took more than one day for any difference to appear, but the bottle with drainage slowly began to dry out, while the soil moisture content of the other bottle remained relatively constant. These results lead to many more questions. What influence would a plant have on the soil moisture content? Why didn't the bottle with drainage show a change for this long? Do different plant species prefer different water contents? Does drainage vary with different soil types? The possibilities for experimentation with this sensor are endless!
Soil Moisture Sensor | Order Code SMS-BTA | $95