Tutorial

Step #1: Gather Materials

The first step of every good experiment is collecting the necessary materials. Most of the supplies required for the Soil Science Lab project can be found in your home or at your local dollar store. If you need help finding any of the materials, check our Bill of Materials for links to other vendors.

Step #2: Collect Soil

Find a location outside to capture your soil sample. This can be in your backyard, your school field, a park, or any other spot with a nice patch of dirt. Make sure to record the coordinates and environmental conditions of your collection site in a notebook or directly into our database entry form. Take pictures to document your experiment for future reference (and for fun!).

1. Locate a spot to collect a soil sample
2. Record the coordinates (latitude and longitude) of your location. Use Google Maps or a similar tool to find this information.
3. Dig a soil sample approcimately 6 inches deep and 0.5 kilograms (~1 lb)
4. Store the soil sample in a container to transport back to your home or school lab
5. Record the following information in your lab notebook or in our database
• Weather conditions
• Humidity levels
• Date and time of day
• Air pollution levels (use EPA site)
6. Take a minute to try and identify what kind of soil you have collected. There are six main kinds of soil: sand, silt, clay, loamy, peaty, and saline.

Step #3: Test Soil

Now that you have an idea for the type of soil at your collection site, let's look at its other properties. For this project, we're interested in the soil pH and its organic matter content. The pH tells us how acidic (or alkaline) the soil is. This factor influences the chemical reactions in the soil and as a result, the organisms living in it. Plants, for example, may have a hard time taking up nutrients if the soil is acidic enough to damage its roots. Soil organic matter represents the fraction of soil comprising of plant and animal detritus (the ecological term for remains). This measure can tell us how much biological activity is going on in the soil.

Test Soil pH

1. Place 3 teaspoons (12.6g) of soil in a clean container
2. Pour in distilled water until moist
3. Agitate the mixture well to form a soil slurry
4. Insert a pH test strip into the mixture. Acidic soil is indicated by red-yellow colors, while basic soil is indicated by green-blue colors.

If you don't have a pH strip, don't worry! You can get a sense for the soil pH using some baking soda and vinegar. Follow the instructions in Aidyl's video below.

Testing the Soil Organic Matter (SOM) is a little trickier. We recognize not everyone has access to an oven that can reach 400 degrees Celsius, so if that's the case for you, feel free to skip this step!

Test Soil Organic Matter (optional)

1. Weight 100 g of soil
2. Use an oven to dry the sample to 400 C/752 F.
3. Remove the sample from the oven and measure its mass. The organic matter in your sample has now been burned away. This is known as "loss on ignition".

Step #4: Make sterile agar Petri dishes

Before you extract the nematodes from your soil, you'll need to prepare a set of Petri dishes. Petri dishes contain a gelatinous substance called agar, which is commonly used by biologists to preserve and grow cells (like bacteria). We will be using these agar-filled Petri dishes to hold our nematodes. For this step, you need the distilled water, gelatin and sugar you collected in Step #1.

1. Boil 240 mL of distilled water in a beaker.
2. Dissolve 20g of gelatin and 20g sugar into the boiling water. Remove from heat.
3. Once your solution is cool to the touch, pour the solution into a petri dish until it is 2/3 of the way full
4. Allow your petri dishes and agar to cool to room temperature (20C) and harden (~4 hours)

Step #5: Isolate the nematodes

Now we're ready to extract the nematodes. Using a simple filter and funnel apparatus, we will allow our nematodes to crawl their way out of the soil by themselves.

1. Create a funnel apparatus by fitting your rubber tube onto the stem of a funnel, then clamping the end of the tube closed with either paperclips or binder-clips
2. Mix 50mg of salt/NaCl with 100mL of distilled water. Pour your salty solution into the funnel and fill the rubber tubing up to the neck of the funnel. (how long should the tubing be?)
3. Line your funnel with a paper towel or coffee filter
4. Place approximately (1/4 cup?) of soil into the lined funnel and cover with another paper towel or coffee filter. Submerge the apparatus in distilled water.
5. Over the next few hours to days, active nematodes crawl through the sieve and soil to the end of the tubing. Opening the clamp allows these nematodes to drip onto the prepared Petri dishes.
6. Use your Foldscope or microscope to view the nematodes up close once you have allowed them to collect on the Petri dish. Take a picture to record your observations and use it to determine what kind of nematode species might be living in your backyard.

Step #6: Upload your data!

We're not done yet! Contribute your observations to our community database so that others can see what you found. The database enables you to compare the soil and nematode properties of your area with those around the world to better understand how factors like climate, human encroachment, and natural disasters are impacting the environment. After you've uploaded your observations, spend some time thinking about how you can analyze the observations in our database to learn more about the world around you.

1. Using the link provided to you by your teacher, or upon completing our New Participant Sign Up, visit our database and complete the form. Make sure to leave any comments or questions you have regarding this procedure, gathering materials, or navigating the database. Your feedback will help us improve our project for future citizen scientists!
2. Make sure to visit our site periodically to collect the latest data drop, an aggregate of the soil and nematode data uploaded by citizen scientists around the world. You can use this data to conduct your own research into any number of topics, including:
• Climate change
• Drivers of soil quality
• Nematode biodiversity