Conclusion

This set of experiments has shown me that soil is the life-force behind everything needed to allow for life to exist. Without the sun, plants could not live or survive, but they also could not if it weren't for the soil they grow in either. We have completed experiments that show everything from how soil is filled with microscopic organisms, to how well it can be used to grow the food we eat. Soil is a necessity for life as we know it and who knows where we would be without it. Prior to this experiment, I saw the importance of soil, but I did not realize just how much of an impact it really has. Soil erosion is literally a life or death issue, and the protection of the slim amount of soil we do have is needed for our continued survival. We cannot allow it to blow away, become polluted or overly salty, or drained of nutrients too quickly for it to re-energize. It must be handled with care as we go into the future and we need it more than ever to be sure we can successfully feed the 7 billion people and counting that our planet holds, as well as protect all the other species that require its continued health. With this knowledge, it makes me question why this information isn't included in a core class. Environmental Science is an elective, but this information is important enough to our futures that I feel it should be taught to everyone, not just those who take this class. Regardless though, I will be walking away with a wider worldview thanks to these experiments and this unit as a whole.

- Andrew

During this experiment on soil, I have come to the conclusion that soil is an indispensible recourse that our planet needs to stay stabilized with the ecosystem. Without soil our world would look completely different. Without soil the types of flora and fauna on earth would change drastically. No animals can produce their own food source, and ultimately rely on vegetable matter as food. During some of the specific experiments for soil we have done, we determined what type of components our soil had. The soil could be the form of three different components: silt, clay or sand. Our soil was mostly silt because it contained no form of hard rocks or grainy rocks; instead it was slippery and wet. Another test that was made with our soil was determining the accurate amount of organic matter it contained. The soil was first heated overnight in the oven. We calculated the weight to compare it to the one being burned over the Bunsen burner. After the calculations were done and measured properly, we determined that we have a lot of organic matter because the soil was found in a very natural and undisturbed place where it was surrounded by humid and temperate conditions. I have learned how to calculate the amount of organic matter in our soil and determine what type of soil we had. Each and every experiment we did with soil have contributed to a better understanding of the importance of soil to the world.

- Kasia

Controlled Experiment

This test was run alongside the remediation process. A small cup was filled with our original soil sample (left), six lettuce seeds were planted, and the soil was watered around once a day over approximately one week:

Over the course of a week, a couple seeds of the lettuce actually began to grow, resulting in a stalk after three days:

And a few days after, now with full leaves:

By the end of the experiment, two stalks of lettuce saplings had begun to grow with a third on the way, and are still growing as I write this post; a stark difference from the lack of any life found in the "remediated" soil:

This shows that our soil sample was at least moderately healthy and fertile as it was, and leaves little to compare to as the "remediated" sample yeilded nothing. Many other groups, though not all, were also seen to have had greater success with their initial samples rather than samples after remediation. A taste test was unable to be done (and I assume could not be unless given months to let the lettuce grow to edible size), but it can be assumed that the lettuce in the natural soil would be healthier and taste better than anything that would have come out the the failure that was the remediated soil.

- Andrew

Remediation

For this experiment, a small cup of our soil sample was "remediated" in an attempt to improve its fertility, or ability to grow healthy, successful plants. A cup was filled to around halfway with our natural soil and the extra space was used to add other elements to try and improve it:

This was mixed in a small tube to make the mixing process easier:

Six lettuce seeds were planted in the resultant mixed soil (right) and watered around once a day over the course of approximately one week:

By the end of the experiment, nothing appared to have grown in our "remediated" sample (left), proving that either we added too much of certain elements to the soil, or the original soil was already fairly fertile:

Our sample was likely already fairly fertile prior to remediation, as there were earthworms, sow bugs, and other organisms that showed signs of healthy, fertile soil. Another connection to an earlier test was the pH level, shown to be ~6.0 prior to remediation but increased for remediation. Although not an average 7.0, 6.0 is itself healthy so remediation of this was likely not necessary. The original soil was found to be mostly silt with a pH of 6.0, so a large amount of sand and clay was added in an attempt to create a loam, pH addition was added to try and bring it up to 7.0, and a small bit of plant food was added for good measure. This proved unsuccessful as nothing grew by the conclusion of the experiment, showing too much of these elements was added and the original may have just been good as it was, as plants did develop in the controlled experiment.

- Andrew

Salinization

For this test, each group in the class made different solutions consisting of water and varying amounts of salt to show how well beans could grow based on the amount of salt present in the water feeding them. Our group was tasked with creating a solution with 3 grams of salt, but because we used 120 mL of water instead of the standard 100 mL, this was converted to 3.6 grams by multiplying 3 grams by 120 mL then dividing by 100 grams, or 3 g x 120 mL = 100 mL x X g goes to 100 X / 100 = 360 / 100 to yield 3.6 g. Six bags containing the beans (our side of the room handled the red beans) and paper towel saturated with the solution were created, and each lab desk was given one of each of the levels of saturation as well as a control bag:

The bags were then surveyed over the course of approximately one week to see which beans grew, how well, and for which solutions did they grow best. The bags were eventually all clumped together on each side:

As the experiment went on, it became evident that lower salt solutions such as 1 g:

As well as 2 g, our 3 g, 4 g, and 5 g were not very good at producing plants from the seeds being placed inside. Most of these beans failed to grow at all. Ironically, the control bag, the solution with no salt, grew very well, as seen here a few days into the experiment (these are the white beans- it appeared that the same results were found for both types of beans, though the white beans did grow a bit more than the red):

And here near its conclusion:

Also, despite 1 g - 5 g being unsuccessful, .5 g of solution also yeilded quite a bit, as shown here a few days in:

And here near its conclusion:

Although not growing as well as no salt at all, .5 g was able to yeild a crop while the others with salt content failed. This proves that a small amount of salt in the water going to plants and crops is okay, but the mass pollution of water supplies with excess salt leads to crop failure and inability to grow as the salt content becomes too high. Drainage improvement, chemical remediation, and the flushing of soil in combination with not allowing for evaporation can all help to remediate overly salty soils. Salt content in soil and water is okay, but can quickly become too much and mst be monitored as such to ensure healthy vegetation.

- Andrew

Soil Dry Percolation Rate

The purpose of this experiment was to measure how fast water flows through dry soil. A small piece of paper was placed on the neck of a 16oz water bottle that has been cut off to act as a funnel. The funnel section is filled with soil to 1 cm of the top. The funnel section was then on the remaining bottom part of the water bottle so it would collect the water as it drained through the soil sample. Then it was done the same way only, we replaced the soil and did clay and sand for the two other bottles, as seen here:

Water was collected at the base of the bottles and used to measure how much was able to collect after 3 minutes through each of the types of soil (from left to right: sand, our soil, clay):

The percolation rate was calculated by dividing the amount collected in each sample by the amount of time it was percolated for. With a diameter of 6.5 cm for each sample, this yeilded:

Sand:

(22.3 mL collected) / (3 minutes) = 7.4

Our soil sample:

(11.1 mL collected) / (3 minutes) = 3.7

Clay:

(8.2 mL collected) / (3 minutes) = 2.7

This data is consistent with the general accepted representations of soil percolation for each of these samples, with sand being the most permeable and clay being the least.

- Kasia

Percent Organic Matter

In this experiment, to find the organic matter percenage, we needed to burn the soil that had come from the drying oven at high temperatures to convert as much of it possible into carbon dioxide and water for 30 minutes. The soil needed to be dry enough to measure and calculate the mass lost during the burning of the soil. The burning is shown here:

It is not necessary to measure the mass of the soil alone because the mass of the crucible is constant and its mass was essentially subtracted out when the percentage of organic matter was calculated. Using the following collected data:

Crucible with organic matter: 83.8g

Weight before burning crucible with organic matter: 74.4g

Empty crucible: 63.3g

It calculated that the total percent of organic matter was 11.2%, using the original container mass (83.8 grams) minus the weight after burning (74.4 grams) to equal 9.4, which was then divided by the riginal weight and multiplied by 100 to find the percent, or (83.8 g - 74.4 g) = (9.4 / 83.8 g) x 100 = 11.2%.

It is very important to have organic materials in soil because it serves as a reservoir of nutrients and water, aids in reducing compaction and surface crusting, and increasing water infiltration, allowing for more successful plant growth and prevention of erosion.

- Kasia

Soil Texture Test

The purpose of this experiment was to calculate the percentage of sand, silt, and clay in the specific soil we have. In the graduated cylinder the soil was put to 60-70 ml mark, then water was poured to the 100ML mark:

Then it was gently shaken to reduce soil lumps. After the procedure was successfully finished, the graduated cylinder with the soil sample was set to wait at least 24 hours to settle the particles in the soil:

The calculations have shown that the soil was completely silted with a small amount of clay. There was a very small variation of soil types in this specific type of soil we had. The silt has medium-sized particles, so it holds some water, but not too much. It holds some nutrients, but not as many as clay. It warms up fast in spring, but not as quickly as sand.  The percentage of silt that existed in our soil was about 90%. Some form of clay was also present in our soil type. About 10% was clay that was forming on the top layer of the soil types. The denser, larger sand particles will settle out first and be on the bottom of the cylinder. Clay is essential to our soil. Clay soil is naturally high in nutrients and holds moisture well, keeping plants hydrated.There was no sign of sand that existed in our soil.  

The pyramid shows the different types of soil types that can exist in your specific soil you have collected.  On the pyramid the bottom right corner, which is silt is the section on the pyramid that is shaded for our soil type:

The 10% of the clay and 90% of the silt lined up the pyramid at the right side where they meet at silt.

This compares to the qualitative method because the calculations that have been taken, result in the percentages that determine the amount of soil type. There was 90% of silt, 10% of clay and 0% of sand. There was no sand that should have rested on the bottom of the graduated cylinder. The qualitative test was done to produce a short "ribbon" of soil, and helped us determine that the soil was silt, as seen here:

Overall, our soil type was consistent with our percolation test results to be that of silt. As we compared our soil types with other classmates, we have come to conclusion that the soil types are very similar. Most of all, they contain little or no sand it all. There was a lot of silt present and less than half of clay. That means that the soil in Lake Zurich is mostly silt and clay. Silt is very fine sediment that is formed by the process of erosion. It is usually found in or near bodies of water or where bodies of water once existed. The city, Lake Zurich has a Lake in its surrounds. We can assume that’s where the vast majority of silt has come from.  

- Kasia