By Andre Alayon
The green roofing project hasn’t just consisted of propagating, setting up modules and installing everything on the roof. This semester we have also been testing the media we’re placing the plants in and the probes that will be used on the roof to record data on the soil.
Throughout the semester a group of students have been going to the lab, taking samples of the media and placing it in crucibles, and measuring their weights. After they take the initial measurements they stick the crucibles in the decimator. Once a week we would take out all the crucibles we put in that week and measure their weight again. This weight will be the weight without moisture. Once we know both weights, we can say both how much water the media had in it and how accurate the probes were.
There was a strong positive correlation between the indicated by the blue line. The 1:1 line was in grey and is what we expected from the results. A majority of the error we had was based on two factors: crucible size and human error.
The media we are using for the green roof has extremely variable particle size. Because some of these particles were rather large, the crucible size was too small. If we had increased the size of the crucible, we would have been measuring more soil each time and would have had more accurate readings. The human error isn’t any one thing in particular. There were a lot of people taking measurements. There is always the possibility that someone mixed up samples, lost some of the soil, used different techniques which resulted in different numbers. Whatever the reason, it was clear that some of the inaccuracy was our fault. Although we could have done better, it was clear that the probes readings were more accurate than ours. This is a good thing. We will grow as researchers from our mistakes. Book knowledge is important, but action and execution are also important. You have to apply your knowledge to see what you really know. This was a great opportunity to do just that.
By Andre Alayon