On the 1st of August we prototyped and installed a humidity and temperature sensor at the Mildmay Community Centre (MCC) garden. The Arduino-based sensor uses a DHT11 humidity and temperature sensor and records to a micro SD card.
In this first attempt we placed the device in a plastic container with six large holes drilled from underneath. The container was hung with hemp rope from a pyramidal bamboo structure, which was secured to the ground. We placed a thermometer and humidity reader next to the sensor to compare the readings.
The device only recorded 589 readings (equivalent of 49 minutes) and we suspect that is is because it flipped by the wind and it was disconnected from the battery supply. During these 49 minutes it recorded a temperature range of 22 to 34 degrees Celsius and a humidity (rH %) of 7 to 37.
At the moment the sensor is being tested again in another garden on a stable surface for a 24hr period. After deliberation with Jenny Littlewood, the main driving force behind the community garden, we opted for building a Stevenson Screen to protect the sensors, which we will install next week.
The volunteers at the MCC have also built a pond and plan to install a water quality sensor in it. They are also building a reed pond to control the water accumulation in the south-east corner of the garden. An additional sensor will be installed there. The purpose of these devices is to open an additional window of understanding about the little processes secretly occurring in the garden. Volunteers can monitor the health of the garden and ponds correlate information from the sensors to that from their observations.