Soil Investigation
You will plan and carry out an investigation to determine which soil type is best for a crop that is commonly grown in this area. You will also learn how to write an IBESS internal assessment.
Day 1
Today you will determine soil texture, pH and nutrient content.
Part 1: N, P and K Tests using Rapitest Kit
Part 2: pH Test using Vernier GoWireless probe
Part 3: Soil Texture
You will use two methods to determine your soil’s texture. One qualitative and one quantitative.
Qualitative
Day 1
Today you will determine soil texture, pH and nutrient content.
Part 1: N, P and K Tests using Rapitest Kit
- Select the appropriate container for the test you with to make.
- Using a dropper, fill the test chamber to the fill mark with the prepared solution. Avoid disturbing the sediment and transfer the liquid only.
- Pour the powder from the appropriate colored capsule into the test chamber.
- Replace cap and shake thoroughly. Allow color to develop for 10 minutes.
- Repeat for each soil sample.
Part 2: pH Test using Vernier GoWireless probe
- Prepare the water-soil mixture. Place 50g of soil into a flask. Shake vigorously once every 3 minutes for 15 minutes. Let it settle.
- Press the button once to turn on the Go Wireless Amplifier. A red LED indicator flashes when the unit is on.
- Launch the Graphical app. Select your Go Wireless pH from the list of available sensors. When the sensor is paired with the software, the sensor LED will flash green.
- Select Events with Entry.
- Place the sensor tip into the liquid part. Make sure the glass bulb at the tip of the sensor is covered by water.
- If the reading is stable, tap Keep to store a data point into the table. You can change the sample description or add a note here. Tap Done.
- Rinse the top of the sensor with distilled water before reusing it and repeat test for each soil sample.
- Take a screenshot or export data table and print your results.
- Press and hold the button for 3 seconds to put the Go Wireless Amplifier into sleep mode. The red LED indicator stops flashing when sleeping and LED light is off.
Part 3: Soil Texture
You will use two methods to determine your soil’s texture. One qualitative and one quantitative.
Qualitative
- Follow the instructions on the chart below to identify the texture of your soil. Yes, you have to get your hands dirty!
Quantitative
The sedimentation test is an easy way to measure the percent sand, silt, and clay in a soil sample. It is based on the fact that large heavy particles will settle most rapidly in water, while small light particles will settle most slowly. The Calgon laundry powder is used to dissolve the soil aggregates and keep the individual particles separated
Materials:
The sedimentation test is an easy way to measure the percent sand, silt, and clay in a soil sample. It is based on the fact that large heavy particles will settle most rapidly in water, while small light particles will settle most slowly. The Calgon laundry powder is used to dissolve the soil aggregates and keep the individual particles separated
Materials:
- 100 mL graduated cylinder
- Rubber stopper
- Calgon solution
- Soil sample
- Add approximately 25 mL of soil to a 100 mL graduated cylinder.
- Add 5% Calgon solution to fill the cylinder to the 50 mL mark.
- Insert a rubber stopper in the graduated cylinder. By inverting the cylinder, mix the solution for 10 minutes. Keep and hand over the stopper to secure it while mixing. So not force the stopper into the cylinder to prevent leaking, as the cylinder may break. Wrap a paper towel around the stopper if it is leaking.
- Leave the cylinder undisturbed until the next class period.
- After this time, the lines that divide the sand, silt and clay columns will be visible. Sand will be on the bottom, silt in the middle, and clay on the top.
- Calculate and record the percent sand, silt, and clay in the soil sample.
- Use the soil texture triangle to determine the texture of the soil sample.
Day 2
Part 4: Soil Porosity
Materials: 250mL beakers, dry soil samples, graduated cylinder
- Design a method to measure soil porosity.
- Calculate porosity as the percent of pore space compared to the volume of dry soil. Record this data.
Part 5: Soil Permeability
Materials: filter paper, 3 funnels, 3 test tubes, dry soil samples, graduated cylinder, stop watch
- Design a method to measure soil permeability.
- Calculate the percolation rate for all three samples.
Part 6: Organic Matter/Mineral Content
Materials: dry soil samples, porcelain crucible, Bunsen burner
- Design a method to measure the amount of organic material in each soil.
- Calculate and record the organic matter in the sample (the loss of mass).
- Calculate the % of humus content.