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Use Smart Sprinklers

We are a LEGO robotics team, called the Robotic Animals. This year’s Lego challenge is hydrodynamics. We looked at many problems that are related to water and researched our household water use. The topic we decided to pursue was gardening with less water. We chose this topic because we looked at our water bills and noticed that in the summer our water usage almost triples.

In the January issue, we shared our findings about some methods that increase plant growth with less water. This month we’ll share what we discovered about the problems with standard lawn sprinklers and our solutions.

One of the problems with sprinklers is that one is only able to control a whole sprinkler zone at a time instead of one individual sprinkler head at a time. If some number of sprinkler heads are in the shade and some are in the sun, we know that the plants in the shade will need less water and that the plants in the sun will need more. If we timed the sprinkler to shut down right after the plants in the shade were sufficiently watered, the plants in the sun would not get enough water. And if we timed the sprinkler to turn off after the plants in the sun were sufficiently watered, there would be pools of water in the garden and there would be lots of runoff.

Many gardens in our area have slopes. Imagine we have a slope in our garden, and we have sprinkler heads all along the slope. We can time the all of the sprinklers to stop after about 10 minutes. If we do that, all of the water at the top of the slope will flow down. Then, that excess water will become runoff water. Slope of land should be considered while choosing the sprinklers location.

We came up with a solution to help us prevent runoff. A smart sprinkler will allow you to control one sprinkler head at a time instead of having to control one zone at a time. That way you can time each one according to their environment. Some of the different places the sprinkler heads might be placed are sun, shade, or in the middle.

To control individual sprinklers, we connected a water sensor and a valve at each sprinkler head. We attached a water sensor to the valve which was connected to the sprinkler. The water sensor would tell us if the soil was wet or dry. If it was dry, it would tell the sprinkler head to turn on. If the soil was wet, then the sensor would tell the sprinkler head to turn off.

We bought a soil moisture sensor for $2. To use that, we bought a kit called Arduino. That cost $30. But, you only need to buy one Arduino kit to use any number of sensors. The moisture sensor basically looks like a two tined fork.

Water Sensors

We came up with three types of water sensors. The first one we decided to use was a basin that will detect the weight of the rainwater. Then, when enough water is in the basin, the irrigation system turns off. Our second solution was to place two electrodes in the basin and when the water reaches a certain height, it closes the circuit and shuts off the irrigation system. Our third solution was to place an inflatable tube inside the basin that will expand when it gets wet. So then, as it is raining, the tube will expand until it flicks a switch and turns the irrigation system off. We decided to use our second solution to help us with our problem.

Our smart sprinkler is one of our ideas. We built it as an experiment, but you can use the solutions we offered in the January article—Mycorrhizal fungi or terracotta pots. Our Mycorrhizal fungi and terracotta pot solutions can be used for both indoor and outdoor plants. Mycorrhizal fungi can be purchased online from several different vendors.

Water is a precious resource, and it is our responsibility to use it wisely. We have to be open minded to adopt new ideas. We need to work together to solve this worldwide problem.

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