School Reports: Fourth block

Mr. Johnston - teacher
Mrs. Carter - student teacher
Primary Authors: Melissa and Alec.
Results contributed by all members of the 4th block class.

Introduction:

The soil gives home to many of the Earth's creatures, without soil we wouldn't exist. Without soil the world would crumble, plants would die out, and if the plants die out, then humans and animals would soon follow. So, all in all we depend on soil to live. The purpose of our lab is to better understand one of the most over looked resource: soil. In this experiment we tested and observed many different qualities about the soil in an area close to our school. The qualities tested and observed were color, texture, consistence, structure, soil pH, presence of rocks, roots, and free carbonates, and the number and depth of the horizons. The main purpose for this investigation of soil was for our class to betted understand the soil around us, and why it is so important to us.

Materials and Methods:

GPS - GPS stands for the Global Positioning System and is the first item used to determine the location of the pit or auger site. Using GPS one obtains the latitude, longitude, elevation, and universal time when one begins working at a site. This information is used later on to tell others who might not know about the position of the site.
Soil Pit - Digging a pit for this lab is one of two options one can chose to look at the soil. If a pit is going to be dug it needs to be 1 meter wide, 1 meter long, and 1 meter deep. We were lucky enough to have a backhoe to dig the pit, saving us a good amount of time. All that was left for us to do was smooth the surface down to expose a fresh face of soil.
Auger Soil - The other option of looking at the soil was to use an auger to retrieve soil instead of looking at a soil wall in a pit. Using the auger one needs to dig a meter deep similar to the pit. One does this by putting the auger firmly into the soil, turning 360 degrees, and then laying the soil collected in the auger onto a tarp or plastic covering of some kind. (Make sure when using the auger to lay the soil as it comes out in the correct continuation of the horizons.)
Horizons - A horizon is a layer of soil. After finishing a pit or an auger site, the next step is to identify the horizons. In groups of at least 3, decide where the horizons start and stop and mark them with nails, straws, etc. Once the group has decided on the horizons then the group needs to measure the horizons starting with 0cm for the first one and then so on till the group reaches 1 meter. (Note: When going to the second horizon and so on start with the number of cm that ended the last horizon.)
Soil Color - The color of the soil is one of the next things that can be observed. To put the color of the soil in universal terms, Munsell Notation is used to categorize it. Munsell Notation is different combinations of numbers and letters associated with the color of the soil. Again a group of 3 is needed to determine the soil color. If the soil contains 2 different colors in it that are spread evenly, then a second color may be chosen. If the soil contains 2 different colors, but one is more predominant then the predominant color is recorded and the other is recorded in the metadata. Do this for each horizon. Also make sure when looking at the soil and color book to keep them in direct sunlight so not to alter the results.
Consistence - The next possible characteristic to look at is consistence. To determine the consistence of a soil, 3 people are to take a ped of soil and see how much effort is needed to crush the ped. The ped has to be one of the following, 1) loose- sand or topsoil [The only time there is a Loose Consistence is when each individual particle of soils falls separately and there is a Single-grained Structure {such as a sand}. Top soil will often be small peds {or units of soil structure} but because there are peds the Consistence will not be Loose; it will be one of the other choices.]; no ped, 2) friable- not much effort, 3) firm- some effort, or 4) extremely firm- need a hammer to crush. Doing this in a group of 3 insures that the results are accurate. Do this, in turn, for each horizon.
Structure - The structure of the soil is determined on the shape of its peds. In groups of at least 3 take turns looking at the soil and decided on the structure of the soil for each horizon. The structure of the soil must be one of the following, 1) granular- cookie crumbs, 2) platey [Platy]- stacks of plates, 3) blocky- chunky, 4) prismatic- vertical plates [vertical columns], 5) columnar- rounded prismatic, 6) single grained, or 7) massive- one chunk. Again, do this for each of the horizons.
Texture - The texture is how the soil feels in one's hands. To determine the texture of the soil 3 people, at the least, will all have to moisten the soil and first see if they can make a "ribbon" with the soil. To make a "ribbon" one takes the moisten soil between the index finger and thumb and smooth it out trying to may a strip of soil as long as possible. After that the group must decide which of these categories the soil would fit in, 1) clay- fairly long ribbon (a few inches), 2) clay loam- barely a ribbon, or 3) loam- no ribbon. Once the group has decided on that, they next need to decide if the soil is one of the following, 1) silt- smooth, 2) sand- gritty, or 3) neither. If it is either silt or sand, add silt or sand to the name of clay, clay loam, or loam, whichever it is. If it is neither then leave the name of clay, clay loam, or clay loam [just Loam as the choices for Clays and Loams are: Clay, Clay Loam, and Loam. See Soil Texture Step-By-Step Guide.] as it is. Do this for each horizon, and remember to moisten the soil, not soak it.

[See Textural Triangle 2 for correct soil texture nomenclature.]

Soil pH - For this test the person doing the mixing needs to be wearing gloves so he/she does not alter the pH by touching the soil. A ped or two will need to be removed from an untouched part of the pit or auger site from each horizon. Next the sample needs to be sieved to remove rocks and such. If the sample is too big and is in a chunk then use a mortar and pestle to grind the chunk. Do this until there is 25 grams of filtered soil for each horizon. Then measure out 25mL of water into a graduated cylinder. Take the pH water with the yellow and then orange pH paper once. Next add the 25 grams of soil to the water and stir the muddy water 5 times ever 30 seconds [The stirring/waiting cycle for this protocol is to stir the soil for 30 seconds and then wait three minutes and then repeat that cycle four more times. See the Soil pH Step-By-Step Guide.] After that let the murky water sit for 3 minutes. Again use the pH paper (both kinds) to find the pH, do this 3 times. (Note: Dip the pH paper into the supernatant, the watery part, only.) Remember to record all 3 numbers.

Presence of rocks, roots, and free carbonates - In this procedure all that is looked at is the presence of any rocks or roots and if the soil has free carbonates. For both rocks and roots all that is done is a group of at least 3 decides whether each horizon has 1) none, 2) few, or 3) many rocks or roots. For free carbonates, though, one person puts vinegar on each horizon, working from bottom to top in the pit. Then soil is then rated on if it reacts, 1) none- no reaction, 2) slight- some reaction, or 3) strong- strong reaction. (After the group has recorded the results make sure to inform whoever is doing the pH where the vinegar was put on the soil.)

Results:

The location of the pit and auger was 34 degrees 43.984'N, 86 degrees 46.829'W, 770ft for elevation, and 19:35 universal time. The data for the pit, which was named Harold, is shown in Table 1 and the data for the auger, which was named Harry Potter, is shown in Table 2. One major pattern that was seen was that none of the soils had free carbonates in the pit or auger. Also in both the pit and auger the soil became moister and firmer the deeper it got. The texture was similar too in the fact the most of it was clay of some sort. Even though between the auger and the pit there were still some major differences.

Horizons	Depth	Moisture	Structure	Color	Consistence	Texture	Rocks	Roots	Free Carbonates	pH
1	0-15cm	Moist	Granular	7.5YR4/4	Friable	Clay Sand	None	Many	None	5.0,5.0,4.5
2	15-21cm	Moist	Granular	2.5YR4/8	Friable	Clay Sand	Many	Few	None	N/A
3	21-64cm	Moist	Blocky	5YR4/6	Firm	Clay	Few	Few	None	N/A
4	64-80cm	Wet	Blocky	7.5YR5/6	Firm	Clay Silt	Few	None	None	N/A

Horizons	Depth	Moisture	Structure	Color	Consistence	Texture	Rocks	Roots	Free Carbonates
1	0-6cm	Dry	Granular	10YR3/4	Friable	Loam	None	None	None
2	6-13cm	Dry	Granular	10YR4/4	Friable	Silt??	None	None	None
3	13-27cm	Moist	Blocky (Rock)	N6	Extremely Firm	ROCK	Many	None	None
4	27-43cm	Moist	Blocky	10R4/8	Friable	Clay	Few	None	None
5	43-64cm	Moist	Blocky	10R5/8	Friable	Clay	Few	None	None
6	64-100cm	Moist	Granular	N8	Friable	Clay Loam	None	None	None

Discussion:

After looking at the result of both the auger and pit most of the results are not too shocking. The fact that the soil was moist was no surprise since our site was located in a fairly swampy area. And most of the soil being clay was also another predictable thing for the majority of the soil around here is clay. Another not so surprising thing was the limestone the auger ran into that is recorded as horizon3. Something that was surprising, though, was the grayish soil in the last horizon of the auger. This gray soil was Jell-O like and smelled weird, maybe some decaying matter or something. I have learned many things I never knew before in this section. For example I had no clue what an auger was or that a horizon was anything other than where land meets sky. I also have learned that dirt's not that bad, and it won't kill you to touch it. In conclusion, this section on soils has been interesting and fun.

SThe Auger And The Pit: The Ultimate Tag Team

Liberty Middle School Soil Lab Report

Introduction:

Materials and Methods:

Results:

Discussion: