Soil Porosity

   

     We found our pore space to be 92mL because we had to pour 92mL of water onto the soil for the water to break the surface of the soil. To calculate the soil porosity, we needed to find the percent of the volume of dry soil that could be filled by water. In other words, soil porosity is the percent of the amount of open space in a given volume of soil compared to the total volume of soil.

92mL of water / 200 mL of soil = .46 x 100 = 46% porosity

Pour it up, pour it up

     The data showed us that there is in fact a lot of empty space between the solid matter that makes up soil in a given amount of soil. Almost half of the volume of our soil was composed of empty space that the water was able to fill. This also allows us to understand how harmful polluted runoff water can be to soil; if the polluted water is able to take up almost half the space of a given amount of soil, the water can do serious damage to the soil and the microorganisms within it.

Soil Dry Percolation Rate

Setting up the test

To measure how fast water runs through dry soil we set up three water bottles with the neck cut off and placed upside down in the remaining bottle to act as a funnel. We set up three so that one would be used for our soil, one for sand, and one for clay. The cross sectional area of our bottle was about 9 pie centimeters. The numbers would make sense because clay is able to absorb water more and slow down the rate at which water runs through it, whereas with sand the particles are larger to where the water falls through it more easily. Our numbers demonstrate this because in the clay the water filtered through at a much slow pace of 0.06 mL/second and even then only 16 mL of the water was able to filter through the clay because the rest appeared to be absorbed. The sand had different results with 20 mL filtering through at a rate of 0.21 mL/second. The sand had a faster rate and less water was absorbed which further supported that clay absorbs more. As seen below, the percolation rate of our soil at 0.19 was closer to the sand than the clay. This would suggest that our soil was more similar to sand, although our past tests somewhat contradict this belief.

            Time Took        Amount Drained

Sand     94.8 s                20 mL

Clay      269.4 s              16 mL

Soil       127 s                 24 mL

after

after (from left to right-soil,sand,clay)

Percent Organic Matter

ooops

The soil started at 28.1 grams after being heated in the oven over night. We then placed the soil on the Bunsen burner, but failed to put it in a crucible resulting in some possible errors in our results. When we checked on our soil it had turned to a reddish brown color in some places. Then the foil started to burn through so some of our soil fell through which could affect the resulting mass. After the Bunsen burner the soil weighed 25.6 grams, suggesting that 2.5 grams was lost as organic matter. This number could have been higher than it should be since some of our fallen soil could account for the difference in weight. With the numbers we got 2.5 grams of the original total of 31.7 grams would mean that about 7.8% organic matter was in our soil. It wouldn't be necessary to measure the mass alone because we are strictly looking at the difference in weight for this portion of the test. If the crucible was included in the first weight and then again in the second weight it would not effect the difference, or the grams that were lost as organic matter. We eventually would need a weight of only the soil, but since we already measured it for the soil moisture we can just use that as our original soil weight in order to calculate the percent of organic matter in our soil. One reason it is important to have organic matter is because they supply the soil with nutrients such as nitrogen, phosphorus, and sulfur. The organic matter also can absorb water which can be released to plants, helping them grow. It also helps prevent erosion because of water infiltration and the soil aggregation, which improves the soils ability to take up and store water.

Soil Texture Test

Qualitative Test:

When performing this test I took about a handful of soil, a little smaller than the size of a ping pong ball, and added a few drops of water to the wad of soil until it was moist. Then, using my thumb and forefinger I squeezed it into a strand that was a couple of inches. Since I was able to at least form a short ribbon we ruled out the soil being mostly sand. However, since it was shorter we came to the conclusion that we most likely had silt or loam, because if it was clay the ribbon, theoretically, would have been able to be longer. Also the feeling of the soil helped us reach the conclusion of loam or silt because it felt a little sticky but not noticeably sticky so we thought it was mostly silt with maybe a little trace of clay.

Quantitative Test:

Before Shaking

For this test we placed 70 mL of our soil into a graduated cylinder and filled it with water to the 100mL mark. The soil was originally a light dull brown but the water made it darker. After shaking the apparatus and mixing the water and soil it formed a dark brown substance. After leaving it out overnight the water again rose up above the soil leaving only one distinct layer of soil. There was about 11 cm of a medium brown color that had spots of dark color throughout and the water had become lightly tinted brown. Based on this calculation that 100% of our soil was the same we would label it as silt. We also took into account our qualitative test though which further strengthened our belief that we had silt because of its ability to form a short ribbon. The small trace of clay that we believed we had due to the ability to form a ribbon caused us to think that we had about 10% clay and not the 0% that the quantitative would've suggested. Therefore, for the clay and sand percentage we accounted for a very low 0-10%, leaning more towards the 0% side for sand, and 10% side for clay. This left about 85-90% to silt which based on our one layer seen in the test would make sense. Based solely on the quantitative test we would have silt, however; taking the qualitative test into account we thought it was more realistic that our soil fell into the silt loam category. Looking at the triangle to the right you can see that they met up at right around where the silt and silt loam categories meet (indicated by black dot), suggesting it is somewhere within that range. This however somewhat contradicts our percolation test outcome because since water took about the same time to filter through our soil as it did in sand, and drained about the same amount of water it suggests that our soil is more similar to sand than clay. Looking at this test we would have expected a greater percentage of sand in our soil than what we saw in our quantitative test. It was difficult to determine which areas were more likely to hold what soils because a lot of it varied and it was difficult to find accurate descriptions of the different areas and how they were developed since most were not necessarily well known or important places. Even our soil, which was from Cuba Marsh was hard to find because it is likely to have many types of soil because it incorporates many different types of land, with some of it being marsh and prairie, along with others. 

after shaking

After leaving out overnight

Soil Moisture Test

Before putting our soil into the oven it was a dull brown color and our sample weighed 31.7 grams. After removing it form the oven it looked more crumbly and hard. It weighed 28.1 grams, meaning that about 3.6 grams of the original soil was water. With 3.6 grams of a total of 31.7 grams as water that would mean that about 11.35% of the soil was water. This goes with our texture results because based on our texture we figured it wasn't as moist as clay but it was not as dry as sandy soil. Since our moisture was a little less than average for soil it would confirm our findings of our previous tests that it is somewhere in between. Based on our soil and other groups' soil we felt there is a correlation because usually if the texture is more smooth and clay like it will also be more moist than a sand texture that is gritty and tends to be a little more dry. This proved true because we found that the groups that had clay had more water in their soil than we did. One of the groups that had clay had almost 5 times as much moisture as we had.

Collecting Our Soil

    We collected our soil from Cuba Marsh. The soil was difficult to get a lot of because once we reached 12 inches deep, we noticed it got more grainy, and it was harder to scoop up the particles. We mostly noticed roly polys and rocks in the soil which was covered by grass and leaves. The soil looked dry and was a light brown. The particle sizes were mostly smaller particles but there were also a lot of clumps. There was a walking path and a lot of trees in the area. The path could effect our results since it means that part of the area has clearly been altered by man. To try and
avoid this we picked a spot away from the path.

Before

Savio hard at work

After

Introduction

Components of soil

     Many people use the words soil and dirt interchangeably; but, fact is they are two different components of nature. Soil is in a sense living, containing microorganisms, organic matter, and insects. Contrary to this, dirt is basically dead soil that is left without the characteristics above that give soil the "living" definition. along with microorganisms and organic matter, soil has other defining qualities as well. Soil's other main components are water, air, and mineral matter. Soil is formed from rocks and minerals weathering; when rocks break down into smaller pieces and mix with organic matter, it very slowly creates the thin layer. as more accumulates and plants and animals decay, it adds to the soil, making it richer. The formation is impacted by parent material, living organisms, climate, time, and topography. When looking at soil texture we focus mostly on particle size, which effects the porosity. With large particles like sand, water falls through; whereas with clay, small particles, it holds in water. The color can also tell us about how rick a soil is. Generally, dark soil is richer than light soil, which can show leaching. pH matters as well because, although soil wants some H+ ions from plants, too much causes the soil to become acidic, which harms the soil and plants.
   

Illinois Drummer Soil

Illinois is dominated by the Dummer soil, characterized for its deep but poorly drained soil. The soil is usually thick, silty, and darker up top and gradually gets darker. The soil is generally good for farming. In Hawaii the main soil is Hilo, which is deep and either dark or sometimes reddish brown. Hawaii however has very diverse types of soil because of the difference in rainfall in different regions of the islands. The climate and soil in Hawaii allows for different farming of more tropical plants unlike the traditional farming of corn in the Midwest. In Georgia the main soil is tifton which is dark gray or brown, and sandy. Soil in Arizona is very deep and well drained. The southern half of Arizona is better for growing crops.

Georgia Tifton Soil

Arizona Soil

Hawaii Hilo Soil

     Farmers should be interested in soil analysis because it can tell them about the nutrients present in their soil and can give insight into which crops will grow best. Knowing what is in your soil can save a farmer time because they will not have to be guessing which nutrients are lacking. It also helps with nutrient runoff because you will not be wasting or adding too much nitrogen or phosphorus by guessing how much to add to crops. Economically it will make a farmer's field more efficient because they will be growing crop and fertilizing them correctly so they will be saving money and producing a better product.