Problem: In this task, you will test the properties of soil.
Estimated time to complete: 2 hours
You will need these materials:
3 cups of soil collected from your garden, a forest, a riverbed, or purchased from a garden store
3 identical glasses (about 8 ounces each)
spoon
small bucket for storing soil
½ cup of vinegar
3 tablespoons of baking soda mixed with 1 cup of water
fine mesh strainer or a colander lined with a large paper coffee filter
½ cup of sand
½ cup of pebbles
tablespoon
measuring cup
Stay safe! Vinegar and baking soda are chemicals that can irritate your eyes. Be sure to wash your hands after working with them.
Question 1: Hypothesis and Data Collection
In this activity, you will examine soil composition. Place one cup of your soil sample in a glass. Slowly add water to the glass until the water comes to the top. Stir the soil and water thoroughly.
Part A
Write down your prediction about what will happen when you let the soil sit for one hour.
Let the glass stand for an hour, and then observe the soil. What do you notice? Record your observations.
Dump the soil and water from the first experiment into a small bucket. Rinse the glass, and get out a second glass. In this experiment, you will test the acidity of the soil. Pour ½ cup of soil into each glass. Slowly pour vinegar onto the soil in one glass, stopping when the glass is full. Slowly pour the baking soda solution onto the soil in the other glass until that glass is full. Record any reaction you see. If there is no reaction, write that down.
It's time to save your soil and clean the glasses for the next experiment. Working over the sink, carefully pour the contents of one glass into a fine mesh strainer or a colander lined with a large paper coffee filter. Rinse the soil under running water, and then dump the damp soil into the small bucket with the soil from the earlier experiment. Repeat with the soil in the other glass.
Part D
You will now test the porosity (the space between the particles) of the soil. You'll compare the porosity of the soil with the porosity of sand and pebbles by measuring how much water fits in a glass with the same amount of each material. Note that the sand will be made up of a combination of fine and coarse sand particles. All of the pebbles, on the other hand, will be of roughly equal sizes.
Set three identical glasses on the counter or table. Put the half cup of sand in one glass, the half cup of pebbles in the second glass, and a half cup of your soil sample in the third glass.
Make a prediction about how much water can fit in each glass. Which sample will hold the most water? Write down your predictions on the porosity of all three samples.
Working with one sample at a time, add water to the glass one tablespoon at a time. Water should soak the sample from the bottom up. Count the number of tablespoons of water it takes bring the water level up to the top of the sample. Record the amount in the chart.
Calculate the porosity of each sample using this formula, and record the results in the chart. "Total sample volume" is the amount of soil, sand, or pebbles in the sample. A half cup is equal to 8 tablespoons
% porosity = (amount of water added to sample ÷ total sample volume) × 10
Did your predictions in parts A and D of question 1 match your observations?
After letting his soil sample sit in water for an hour, Mark concludes that just one type of material made up the soil. Jack concludes that the soil had several different materials, each with a different weight. Based on the results of your experiment, whose conclusion do you support and why?
Vinegar, an acid, reacts with base, or alkaline, substances. Baking soda, a base, reacts with acidic substances. Based on your results in part C of question 1 do you think your soil is acidic, alkaline, or neutral?
The ideal pH of soil is between 6.0 and 6.5. This pH allows most plants to grow. What does that mean for soil that reacts with vinegar? Need Assignment Help?
Soil aeration is a technique that makes holes in the soil. Based on the results of your experiment, how does soil aeration affect the porosity of soil?
Why is soil porosity important for plant growth?