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

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.

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Great to hear about perseverance in the face of challenges, and good use of creative thinking and problem solving!
Medford Middle School SMAP

I voted five stars for doing what you did against all odds. The field manual does not define a sample can. Nor does it explain why you need to make a hole on its bottom, nor why you need to pound the can into the ground rather than dig with a trowel to 5 cm deep and put the sample in the can.

I have dented so many cans trying that especially since the SMAP manual on the NASA website says that the sample should come from undisturbed earth, ruling out cultivated and irrigated areas. Where I am, you'll hit rocks 95% of the time if the field is not cultivated. And rocks have to be removed from the sample. So it is best to use a trowel.

SMAP lost its active part from the malfunction of the amplifier and join me in suggesting to Brian that we can simplify our support for the SMAP mission through gravimetric measurements only, given that one gram of water is one cubic centimeter. The difference due to temperature is negligible. For this simplified support we need a new data entry form, one that guides you to a definition of "dry." The form shall call for three weight measurements, one after 8 hours in 105°C or 220°F oven; the next, after 4 hours; and the third time, if needed, after 2 hours. I use an old toaster/oven that allows me those settings. All you want is to boil that water out without changing the chemistry of the soil. Depending how wet the sample is, the first drying could be longer or shorter. If the weight does not change at the 2nd drying by more than .5 grams, the sample is dry and you do not need the third drying.

Until Brian gets a new data entry form, just record your measurements in a journal, noting date and time the sample was taken. If you have a team with four or five members, you can take turns getting a soil sample every day, weigh it (soil and container) immediately each time and wait till you all have your samples. Then dry all of them at the same time on a weekend. From the difference in water moisture in each daily sample, your team can get an idea of the rate of evaporation of the soil moisture in your sample area. This data you can pass on to a gardener. It might help him adjust his sprinkling needs.

When you have data for a year, you can graph the rate of evaporation for each month, again something you can present to farmers.

Now connect your study of soil moisture with one day having to do with Martian soil. You’ll be the experts when that time comes and its not that far off.

Last July, a group of GLOBE students, their parents, some GLOBE trainers from Africa and Japan went to tour Space X in Hawthorne, CA. Elon Musk’s office was upstairs and we could tour only the ground floor but we have seen and heard enough of him on You Tube to bother him. He is busy with plans to get to Mars in 10 to 15 years.

Check out Space X website, especially in the Spring. The Mars Colonial Transport will be out by then in concept form.
While you are on the website, check out Space X internship program. Think of Middle School and High School as time to build a portfolio that would get you that internship. As soon as you get admitted to a 4-year college, send out an application form for this internship. And do it every summer until you get selected. That could be your ticket to a good job. And to Mars!
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