Nicole Taylor Testing Soil Lab Background: In this experiment we went through a series of five tests to determine soil productivity. These tests include water holding capacity and capillary action of soil, qualitative analysis of ion exchange capacity, analysis of free ions, determination of soil permeability, and particle size distribution. To be considered farmable land must meet several requirements the hardest of which is soil productivity. The way water is held and moves through soil is critical for ideal plant growth which we studied in activity one, water holding capacity/capillary action of soil. Soil must also be able to retain nutrients and the ability to do this depends on the number of charged ion-building sites per unit of soil. In the second activity, qualitative analysis of ion exchange, we studied this. Activity three, analysis of free ions, also looks at the soils ability to hold ions but looks at the specific nutrients of nitrogen, phosphorus, and potassium. These nutrients are some of the most important to crop growth and soil productivity. Permeability is the state that allows liquids to pass through it and it is important when considering soil productivity which we looked at in activity four. Soil composition is a very important aspect of soil productivity. Each component (sand, silt, clay, humus) have a different particle size. The difference in size leads to different characteristics of each component. We looked at particle size in test five. Purpose: The purpose of this experiment was to discover what type of soil is the most productive. We used several different soil types and compared their results to the following tests; water holding capacity and capillary action of soil, qualitative analysis of ion exchange capacity, analysis of free ions, determination of soil permeability, and particle size distribution. After analyzing the results of those tests my group did our best to compose the most productive soil. In activity six we experimented with our creation. First we created our ideal soil, the one we thought would be the most productive. We then compared it with samples of mostly clay and sand soil types. We decided to grow alfalfa and see how well it grew in our soil samples. The results can be seen at the end of this packet in activity six. The results of the rest of the tests can be seen below. Activity 1 1. The amount of clay in the soil is most important in determining water-holding capacity. In our lab the clay sample had the highest water holding capacity. 2. The longer the soil can hold the water the better the crops will grow and the more crops the ecosystem can support. 3. To regulate our unknown sample's water-holding capacity I would add clay because it has the highest water-holding capacity and right now our sample has the lowest of the soils. 4. An advantage of soil composed mostly of sand with a high capillary would be that area would be less likely to flood because the water could easy permeate through the soil.
Nicole Taylor Activity 2 1. Sand and humus had the least ability to hold macronutrients ions, next would be the collected sample, then just sand and finally with the highest ability to hold macronutrient ions is the sand and clay sample. 2. The soil samples have a more negative charge so the crystal violet would easily be absorbed in a small amount of soil but with a larger amount Crystal Violet just stays at the top. 3. Crystal Violet has a positive net charge the sample that retained Crystal Violet the best was Sand and Clay. Eosin Y has a negative net charge (most soils have negative net charges) sand, sand and humus, and the collected sample all retained Eosin Y the best and have a negative net charge. 4. Soil needs to be able to exchange ions because plants need different amounts of certain minerals and nutrients that have different ions. The ions available helps to determine what plants will grow there. 5. I would add clay to the sample because it has the highest ability to hold ions and the longer the ions stay in the soil the better chance that the soil will be able to exchange ions. Activity 3 1. The nutrients in the soil and the water that goes through it (rainfall), the amount of organic matter decay, and the type of crops growing can all influence the soil's acidity. 2. When acid is added to soil it can erode away the soil into one that holds less nutrients and eventually the nutrients will be depleted. 3. The PH of the soil can cause nutrient depletion. Depending on how acidic the soil becomes from rainfall and other factors listed in question one, the soil can become eroded and lose the ability to hold nutrients. 4. To fix nutrient depletion in the soil you can spread fertilizers, even natural ones like animal manure that physically put the nutrients back into the soil. Also practicing good agriculture such as crop rotation to reduce erosion will keep nutrient depletion from happening. 5. Our soil sample was most deficient in the K test; it was also depleted from the P test. Activity 4 1. The smaller the particle size the slower the percolation rate. In our experiment water took the longest time, had the slowest percolation rate, for the clay sample. Clay has very small particles that stick close together. In contrast water went through the humus the fastest and humus had the biggest particles. 2. The clay field would become more likely to flood because clay has a slower percolation rate. The rainwater would take much longer to soak into the clay soil but it would stay there longer than the sandy soil. 3. To increase the soil's permeability, the state that allows liquids to pass through, I would add humus because it has the fastest percolation rate and therefore the highest permeability. Activity 5 1. The soil particles had time to settle will in the jar overnight. They settled into different soil levels with the heavier and denser particles settling on the bottom. 2. My hypotenuse regarding the unknown sample's soil composition was fairly correct. I had guessed that half of it would be the silt and that was correct. I guessed that clay would be 25% and the sand would be the other 25%. It turned out to be 33% and 17%; which is fairly close. The amount of each soil particle pretty much followed the other test results.
Nicole Taylor Activity 6 Hypothesis: I predict that the sample we mixed based on the results of the previous five tests will be the most productive. Procedure: The materials you need for this experiment include; 3 strips of plastic pots, collected soil sample, sand sample, clay sample, tablespoon of alfalfa seeds, grease pencil, and mixing cups. 1. The first thing you must do is create the sample soil mix. Fill a mixing cup with ½ cup of the collected soil. Then add in 1/3 cup of clay and finally mix in 1/6 cup of sand. Mix up the sample so each soil sample is evenly distributed. 2. Acquire three strips of plastic pots; each strip should contain four pots. 3. Add the sample soil sample you just created to all of the pots of one strip. Fill the pots about half way-mix more of the sample if need be by following the measurements above. 4. Add the sand sample to all the pots of one strip. Fill the pots halfway. 5. Add the clay sample to all of the pots of one strip. Fill the pots halfway. 6. Using the grease pencil label each strip with the type of soil it contains. 7. Count out and add 20 alfalfa seeds to each pot. Gently press the seeds under the surface of the soil. 8. Add 20mL of water and place all pots in an area with ample light. Keep the light level equal for all pots. (We used artificial light.) 9. Add the same amount of water each day to each pot at the same time of day for nineteen days. 10. Create a data table and make observations each day.
Nicole Taylor
Data Table: Our observations are listed below in the the data table.
02/03/12 Weekend 02/06/12 02/07/12 02/08/12 02/09/12 02/10/12 Weekend 02/13/12 02/14/12 02/15/12 02/16/12 02/17/12 Weekend 02/20/12 02/21/12 02/22/12 02/03/12 Weekend 02/06/12 02/07/12 02/08/12 02/09/12 02/10/12 Weekend 02/13/12 02/14/12 02/15/12 02/16/12 02/17/12 Weekend 02/20/12 02/21/12 02/22/12 02/03/12 Weekend 02/06/12 02/07/12 02/08/12 02/09/12 02/10/12 Weekend 02/13/12 02/14/12 02/15/12 02/16/12 02/17/12 Weekend 02/20/12 02/21/12 02/22/12
Clay Pot 1 Potted
Clay Pot 2 Potted
Clay Pot 3 Potted
Sprouted Alive Alive Alive Alive
Sprouted Alive Alive Alive Alive
Sprouted Alive Alive Alive Alive
Alive Died Died Died Died
Alive Alive Alive Alive Alive
Alive Alive Alive Alive Alive
Died Died Died Sand Pot 1 Potted
Died Died Died Sand Pot 2 Potted
Died Died Died Sand Pot 3 Potted
Sprouted Alive Alive Alive Alive
Sprouted Alive Alive Alive Alive
Sprouted Alive Alive Alive Alive
Died Died Died Died Died
Died Died Died Died Died
Alive Alive Alive Alive Alive
Died Died Died Died Died Died Died Died Died Collected Sample 1 Collected Sample 2 Collected Sample 3 Potted Potted Potted Sprouted Alive Alive Alive Alive
Sprouted Alive Alive Alive Alive
Sprouted Alive Alive Alive Alive
Died Died Died Died Died
Alive Alive Alive Alive Alive
Died Died Died Died Died
Died Died Died
Died Died Died
Died Died Died
Nicole Taylor Graphs/charts: The following graphs give a better visual of the data we collected during activity six.
Nicole Taylor
Analysis: My hypothesis from the beginning of this experiment turned out to be wrong. The alfalfa survived better in the clay sample. When we first designed our original soil sample we had wanted to have more clay than sand because clay holds on to the water longer and would keep our alfalfa more hydrated. Our results show that we did not use enough clay. We also used more clay because it has a higher ability to hold ions. We had thought the amount of sand we used would be good for flood control and getting water to the roots right away. An observation worthy of note is that all of the plants ended up dying after the weekend of the 18th & 19th. That week we also had school off on the 20th & 21st. Those four days without water was most likely the cause of alfalfa death and had little to do with the soil productivity of the remaining plants. If I were to do this experiment again I would change the soil sample by adding more clay. I would also have the watering be more consistent. Long weekends without water do not bode well for plant growth.
