Week 8 was a turning point. After weeks of research, brainstorming, and trying to hypothesize how the environmental monitoring stations would be installed, we finally got to test out our theories. We started the installation of the first environmental monitoring station on Monday in plot G7 of the Willie Streeter Community Garden. Since we are renting this plot, it was the perfect place to test out our installation plans and perfect our technique before we had to install any equipment on campus or in the orchard. We wanted to learn to install the soil moisture sensors without having to disturb much of the existing land cover.
Once the 4x4x8 cedar post was stabilized, we were able to get the air temperature/relative humidity/dew point sensor, the solar panel, and the data logger/data transmission station installed.
The soil moisture sensors are shown zip-tied to the mounting post, for later installation.
The solar panel is mounted on the south side of the pole, to maximize the solar exposure. It was exciting to open the data logger and see “charging” flashing as the solar panel recharged the battery! The air temperature/relative humidity sensor (encased in the solar shield) is mounted at 6 feet (near-surface air temperature), on the northern side of the post. To avoid interference, the data logger has to be at least 12 inches away from sensors, so it is mounted on the south side of the post as well.
We utilized a lot of zip ties to hold equipment in place while we determined optimal mounting procedures.
We ended up having to use luggage locks to secure the data logger case, as regular pad locks were too big to fit through the provided holes.
A close up of the solar shielded air temperature/relative humidity sensor.
The soil moisture sensors come with very long cables. One (of the many) installation challenges was to figure out how to contain and protect the excess cable. We spent several hours on Tuesday trying to figure out how to protect the cables. Onset, the company that made our equipment, was not as helpful as I had hoped. We called to talk to one of their tech people, but she did not have any experience with the soil moisture sensors. In their Deploying Weather Stations: A Best Practice Guide, the recommend that soil moisture sensors be protected by conduit.
The illustration in the guide showed what appears to be a thin PVC pipe protecting the cable both above ground and extending 12 inches below ground. However, the soil moisture sensor is on one end of the cable, and the sensor electronics are on the other end of the tube (as shown in the photo below).
Due to the sensor and the “signal changer” (as the Onset representative called the computer equipment tube), the smallest diameter pipe that could be used to protective the equipment for be 1 1/4 inches. A pipe of this diameter would be an open invitation for underground dwelling animals to take up residence. To further complicate matters, the specific soil moisture sensor installation guide (see below) shows no protective conduit underground. So, should the sensors wires be protected by conduit or not? The conflicting publications were a source of frustration.
So we spent a lot of Tuesday trying to get answers to our questions and try to see if there was a “split tube” option to protect the wires. We had already decided to run the above ground sensor wires through tubes that were designed to cover cables in the interior of a house or business (you will see the white tubes in photos above). These tubes opened up on one side and were flat across the back, designed to be mounted on the wall. However, those tubes were not practical for underground installation.
While I explored protective options for the underground wires, Dr. Habeeb started working on installing the sensors. For proper soil moisture measurement, it is important that the sensors are installed in undisturbed soil. After a pilot hole is cut at a specific depth, the soil moisture sensor is carefully inserted into the side of the hole.
The red tube that you see is a flexible plastic tube that is slit down the side. We decided that is would provide an extra layer of protection from pests and the elements.
Two soil moisture sensors were installed in the garden plot. One is installed 30 inches to the west of the mounting post (the red tubing), and the other (in the blue tubing) is installed 30 inches to the east of the mounting post. Both sensors are installed at a depth of 6 inches below the surface. We will be able to experiment with watering the ground above one of the sensors and seeing the comparable difference.
The finished installation. You can see markers in the ground to indicate where the sensors are located and to show the path the cables are taking underground.
To contain and protect the excess sensor cable that was mentioned above, we used a case designed to protect exterior electrical outlets.
The case conveniently had two openings for cables at the bottom. So RMS_1 (Remote Monitoring Station #1) was completed at Willie Streeter Community Garden on Wednesday.
So, I assembled the second station Wednesday night so that we could start the next installation (and get more data!)
Thursday morning’s installation was at the Bloomington Community Orchard. We can secured permission for us to mount our equipment on one of their existing poles. So, the good news was that I did not have to create the mounting post, but the bad news was that I had the challenge of working around trees, existing vegetation and wires on the trellis.
The data logger is mounted on the north side of the pole, and the temperature/relative humidity sensor is on the west side of the pole to avoid the tree branches.
The equipment is adjacent to a pear tree.
This photo shows the solar panel in place on the south side of the pole, again to absorb maximum solar radiation. I had to gently relocate one of the pear tree branches to the north side of the pole so that our solar panel was not blocked. In the foreground of the photo is an information case where we will be able to provide information about our environmental monitoring system, once the public access portal is created.
Soil moisture sensors are again zip-tied to the post while we confirm with the orchard management where we can dig to install the sensors.
A view of the southern side of the equipment.
One of the challenges with this installation was mounting equipment around the wires on the posts that support the trellis.
After much time experimenting with the laser cutter and our two-layer acrylic, I was finally able to cut a sign Friday morning to label our equipment. The first sign was mounted in the garden.
Friday’s installation of the soil moisture sensors in the orchard was very different from the installation in the garden. First, we were working to try to disturb as little of the existing vegetation as possible. Second, the soil was a different consistency, and much easier to dig in, at least closer to the surface.
For the orchard, since installing sensors 30 inches to the west of the post would have meant attempting to install a sensor in the middle of an old gravel walkway (which resembled trying to dig in concrete), we installed both sensors at the same location (30 inches to the east of the pole). One sensor is at 6 inches, and the other sensor is at 10 inches.
The identification sign was added to the orchard mount. For the second installation, we improved on the mounting technique and used braces to mount the sensor tubes (one is for the temperature/humidity sensor and the other two are for the soil moisture sensors), instead of zip ties. By the end of Friday afternoon we had two environmental monitoring stations up and running. The data collection has begun!
Outside of the sensor installation this week, we had the opportunity to work with the Girl Scout camp on Monday, helping to teach them paper circuits and how to solder.
Last week I had the opportunity to present my research to the ProHealth students and faculty during our weekly Friday morning meeting and also present my “Lightning Talk” with the rest of the REU students during Friday afternoon’s ProHealth Tea.
After my presentation, Dr. Habeeb corrected some of my information about the importance of near-surface air temperature measurements in microclimates. Weather stations may be situated on the ground, but one or two weather stations are used to predict the weather for an entire region, not a specific location. Satellite data is pervasive, but satellite signals will bounce off of any “skin” or surface that they encounter, whether it be the earth’s surface, buildings, trees, or even clouds. The data is not necessarily accurate for near-surface temperatures that we encounter when we go outside. The resolution for many satellites is 1 km. There can be a significant difference in microclimate temperatures within that region. The Landsat satellite does provide a better resolution, closer to 30 m, but it only passes by a certain location every couple of weeks and only at a specific time of day. It can not measure the fluctuations in temperature throughout the day at a specific location. All important information about why our research is so valuable!
Dr. Siek suggested adding a map of Bloomington showing the confirmed and desired “wish list” sites of the sensors, showing photos of the actual installations. Add circles or boxes to diagrams to focus the attention on pertinent areas. Detail how watering the plot, or areas of one sensor and not another, will affect data. Describe how Bloomington and the surrounding area fit into the bigger picture in terms of “urban” characteristics.
My presentation slides for my general presentation are linked here (https://iu.box.com/s/mwd0lolbz3b73frhvpk6b891hvywid7c) and last week’s “Lightning Talk” can be found here.
My initial draft of the poster was something like this:
but Kiarra and I decided that with the diagonal lines, it would be difficult to use the space effectively, so she came up with a much simpler design:
Coming soon: video storyboard!