In order to make the roof deck garden “smart”, we need to incorporate sensors for several reasons.
- To automate watering with the irrigation system, we need to be able to sense soil moisture
- To understand if we can use zone-related outdoor planting information like when to expect the first and last frost, we need to know soil temperature and air temperature. This will help us understand if the soil temperature drops earlier than it would on the ground.
- To learn more about the garden itself and help plan for future years, we want to sense hyper-local weather and collect data such as outside temperature, humidity, wind speed, sunlight, and barometric pressure. Some of this data might also be possible to get if we have a weather station very close that provides data we can use.
We know that we want to have our garden control itself using certain data, as well as have a cool factor. For example – if the soil moisture sensor says the soil is dry, but we know it’s going to rain later that day, the system should not enable the drip irrigation. This type of data can’t be sensed directly, but needs to be downloaded from a weather service. For example, this blog post shows how to use data from weather underground.
Since soil moisture is the most directly necessary to the function of our garden, we decided to focus on that first. So far, we have experimented with the Soil Temperature/Moisture Sensor SHT10 from Adafruit. On the Adafruit website, there is information on how to connect the sensor in the circuit, as well as example code to make it work. For prototyping, we just used electrical tape to secure jumper wires to each of the four colored wires in the sensor cable.
The next step is to decide what data to collect ourselves and what data to gather from online weather sources. To make the most out of this project, we think we’ll try a combination of both so that we can learn how to integrate data from different sources and compare our hyper-local data with that from a weather service.