Conclusion

Melissa
Throughout this lab, I learned that soil is not only a nuisance. Soil is the basic component of which all life originates. Food chains and ecosystems all start with a base of soil. The bottom and backbone of the food chain, plants, are only able to exist through soil. The different components of soil determine what kind of life can survive there. Soils with little nutrients, such as phosphorus or nitrogen depletion, do not have as high a productivity as soil with high levels of organic matter. Certain plants that can withstand high levels of salt exist in soils with high salinity. In this experience, I learned how to evaluate a soil's composition and use that information to remediate it to create a highly productive sample. If I were to plant a garden, I now know how to test for nutrient levels and which fertilizers (organic, inorganic) would create a desired effect. The lettuce plants grown in the controlled experiment are still young but we are continuing this experiment.


Hannah
This lab has taught me a lot about soil, and that there is a lot more to it than many people, including myself, may have thought. Soil is very different depending on where it's from and has many specific components that make it the way it is. It is the basis of life in any ecosystem. For example, things like soil erosion from invasive species can be very damaging. Also, even minor changes in soil such as the addition of salt, can also be very damaging and people should be aware that their actions have consequences to the soil and life around them. I learned how to evaluate many different aspects of soil such as its composition. I also learned that different kinds of soil hold water differently. Knowing what I do now, I feel as though I could successfully grow plants now that I am aware of what fertilizers and chemicals can do to them. I also learned from our remediation lab that natural soil may be just as good as fertilized soil for some plants. Some plants also require specific levels of pH and nutrients and it is important to retain those levels. Soil is vital to our environment and needs to be protected as much as any animal or plant species.

Controlled Experiment

To have a comparison to our remediated soil we created a controlled experiment. We put 67 grams of soil in the cup and planted 5 seeds. Every other day we watered the plants the same amount at the same time.

Day one of control and remediated soil

Control and remediated soil after a few days. They are growing very similarly.

Both cups after about a week. They still appear the same.


In conclusion, our remediation process was not particularly successful. However, it did not yield any negative results either. Compared to the control they look roughly the same and all 5 seeds grew in both cups. Although in the remediated cup, one plant appears to be dying but it is hard to tell whether that is a result of the soil or some other outside force. Every plant has two leaves and is about the same size and color. If you were to taste them, I assume they would taste the same since the fertilizer had little effect on the remediated soil.

Remediation Process

To remediate our soil we looked at our results from the fertility analysis. Because our soil seemed to have fairly high levels of necessary nutrients, we felt that we didn't need to add very much to fix it. This is likely because that although we could not see any microorganisms in the berlese funnel test, there were many other organisms such as worms that naturally fertilize the soil. This could also be due to the percent organic matter that we found to be about 27%, our soil was naturally a good source of nutrients. The pH was a little over 7 which is roughly the ideal level needed to grow lettuce, so we did not change it. We filed the cup with 67 grams of soil (same as control). Then, we measured 1.9 grams of inorganic soil in proportion with the amount of soil. Next, we added 9.7 grams of organic manure fertilizer. We planted 5 lettuce seeds and watered them both the same amount. We expected that these extra nutrients provided by the fertilizers would result in healthier lettuce plants that grow large and faster than the control soil.

Day one, notice the remediated soil looks finer and richer

Salinization Test

This test was not done on soil, however it showed students how salt levels can effect soil's productivity. Seven different bags were filled with 5 white beans wrapped in a paper towel. Solutions of regular table salt (NaCl) were created so that each solution had a different concentration. They were: 0g NaCl/100mL H2O, .5g NaCl/100mL H2O, 1g NaCl/100mL H2O, 2g NaCl/100mL H2O, 3g NaCl/100mL H2O, 4g NaCl/100mL H2O, and 5g NaCl/100mL H2O. Each bag was given 20mL of the salt solution of varying concentrations.

 

 The bags were sealed to prevent evaporation. After a week, the bags were examined to assess the beans' growth.

0g NaCl showed the most growth

.5g NaCl showed the second most growth

2g NaCl had few sprouting beans

3g NaCl had no growth

4g NaCl had no growth

Not visible, but 5g had no growth

1g NaCl had one sprouting bean

From this test, it can be concluded that high salinity levels halts soil production. To remediate salty soil, calcium ions must be added to balance the sodium ions. A good source of this is gypsum. It is not recommended to water down over salted soil because the salt particles may be carried into runoff and cause the same problem in fields elsewhere.

Potassium Test

Chart for Reference

In order to find the potassium levels of our soil sample, we added 2 grams of soil to a test tube of potassium extracting solution. We shook the mixture for one minute and then let it settle. Then, we extracted the liquid from the test tube and put it into a second test tube. In the second test tube we added one potassium indicating tablet. We mixed the solution until the tablet dissolved and was a purplish color. We continued to add 14 potassium test solution drops until the color changed to blue. Based on the chart provided, our soil sample's potassium level was medium. Although this seemed to result in healthy plants in the area, maybe higher levels would result in even healthier plants.

Finished Experiment

Phosphorus Test

To find the level of phosphorus in our soil, first we mixed the Phosphorus extracting solution with 1.5 grams of soil for one minute. Next, we allowed the soil to settle. After it was setttled, we took the liquid from the top and put it in another test tube with phosphorus indicator reagent. Next we added a phosphorus test tablet and shookthe solution until it dissolved. The solution turned a dark blue color, indicating that phosphorus levels are high. Beause phosphorus is often included in fertilizers, high phosphorus levels are ideal for plants. This is proven with our soil because the plants growing in it were numerous and healthy.

Chart showing phosphorus levels

Finished Solution

Nitrogen Test

In order to test the nitrogen level of our soil, we first filled the test tube to line 7 with nitrogen extracting solution and added 1 gram of soil to it. We mixed it in the test tube for one minute and then let the sample settle to the bottom. We then took a pipette and extracted the solution from the test tube into another test tube and added nitrogen indicator powder to it. We mixed it and after 5 minutes a light pink color started to develop. The Nitrogen color chart told us that our soil's nitrogen levels were on the low side (0-30 lb/acre). Although the plants growing in our soil looked healthy enough for the level to be considered fine, most plants probably would thrive better in soil with slightly higher amounts of nitrogen.

Completed Nitrogen Solution

Nitrogen color chart for comparison