GUEST BLOG from Medford Memorial Middle School in Medford, NJ: Testing and Finessing Soil Moisture Measurements - Brian Andrew Campbell

Hello from Medford Memorial Middle School in Medford, New Jersey.

The quest to get an accurate soil sample continues at Medford Memorial Middle School, Medford NJ. Hello, we are the students of Memorial’s Citizen Science Education Program. We’re excited to be part of the SMAP campaign, but have not yet been able to enter any data.  Here’s a brief overview of our journey.

First, we learned about SMAP as a satellite, and then we studied the protocol. We didn’t have any soil sample cans, so we settled on a sturdy coffee can, Ryan had brought in from home. Ashwin measured 5 cm from the “top” of the can and put a piece of tape around the can, so we would know how far to push the can in the soil. We decided because there was enough space in the can when we turned it over, we wouldn’t need a hole in the “bottom” of the can. We had a small hammer, and a clip board, instead of a piece of wood. We were ready…or so we thought.

It was apparent right away, our clipboard as a substitute was not going to work. After just five whacks by Jill  with the hammer, the clipboard gave way and broke! Jill’s strong, but not THAT strong. We ran inside and found a “sturdy” piece of wood about 1 – 1 ½ inches thick. We started hammering again! But, the wood wasn’t strong enough, either. In fact, little pieces of wood started to fly everywhere and hit Riley and Daniel in the face (they were holding the wood) and we soon realized we should be wearing goggles. In addition to a thicker piece of wood, Daniel suggested we use a mallet, perhaps made out of rubber, so the force of the “hit” would be spread out more and not so concentrated. We did get the can into the soil, and Gabby got it out using a large kitchen spoon. She put the can in a zip-top baggie. We actually poured the soil back into the hole, because we had run out of time. The bell rang and we were finished for the day.

On our next attempt, we were ready! We were armed with a new rubber mallet, a new gardening spade (trowel), an 18” section of a 2” by 4”, our trusty coffee can (and now a plastic lid, instead of the baggie) and safety goggles. We went outside, and got our sample. Everything was going according to plan, until we came inside. When we went to measure the soil in the coffee can, we got an error message on our electronic balance/scale. The can and sample exceeded the max grams allowed for that particular instrument. The soil at our testing site is packed really tightly and absorbs a lot of water. We decided to dry the soil anyway, just to check out our heat lamps, but after three days under the lamps, the sample still wasn’t dry.

OK, we had to be smarter than the soil, can and heat lamps. We poured the soil out of the coffee can onto a microwave safe dish, measuring the soil and dish, instead of the coffee can and soil, and then put our sample in a microwave. Luckily the bell rung before we could start the microwave and the next day, our teacher, Mrs. Gorman had to speak at the Science Teachers Meeting in Philadelphia. It was there she met “Scientist Brian,” in person, who warned her about using a microwave. If there were high metal counts in the soil, the door of the microwave might blow off!!!!!

All right…we promise our story will finish soon. We knew what we were doing for the outside portion of the experiment was working. Now, we needed to fix the inside portion. Since our 5 cm of soil produced a large amount of soil, we decided we would use a ceramic tray as the “holder” of the soil, once we poured it out of our coffee can. We found a scale that measured up to 6000 grams. The only problem was that anything greater than 500 grams was measured in whole grams and not tenths. We figured we’d work that out later. We took our measurements, put the tray and soil under the heat lamps, and after approximately 16 hours of drying time, we had dry soil. Yay!!!! We took another sample of soil the next day, and everything worked. Now it’s time to input some data in GLOBE!

***A NOTE FROM THE SMAP TEAM - A coffee can will not provide an accurate sample size and will not allow for a correct volume measurement.

Also, you should never use a microwave, toaster oven, hot plate, kitchen stove or kitchen oven to dry the samples. Use only a soil drying oven or the heat lamp method for drying the soil samples.