You’ve learned that soil is a resource we can’t live without. We grow our food in soil and it filters our water and air. Soil is also very important for human health because both diseases and their cures can come from soil. You may think that soil wouldn’t be much help to you if you got sick, but if you’ve ever needed a medicine called an antibiotic, soil has already helped you!
WORDS to KNOW
antibiotic: a substance that destroys bacteria or stops it from growing.
THE SOIL CURE
Remember, organisms called bacteria and fungi make their homes in soil. There can be good bacteria and bad bacteria, just as there can be good fungi and bad fungi.
ESSENTIAL QUESTION
What would happen to our health if we had no soil?
In the early 1900s, a scientist named Alexander Fleming discovered something about a soil fungus called Penicillium. It could stop a bacteria called Staphylococcus from growing and spreading in a petri dish in his lab. Penicillium was used to create penicillin antibiotics. Penicillin is used to fight many serious diseases, such as pneumonia.
WORDS to KNOW
petri dish: a shallow dish with a loose cover that’s used to grow bacteria and other microscopic organisms in a lab for scientists to study.
pneumonia: (noo-MOW-nyuh) an infection of the lungs.
resistant: something that stands against something else.
Many of the antibiotics we use today start with soil organisms. This is one reason it’s important to keep soil healthy. Some scientists fear that by not taking care of the planet’s soil, humans are in danger of destroying possible cures we haven’t yet discovered.
HEALTHY PLANTS, HEALTHY HUMANS
What happens when you stay up late and eat lots of junk food? You might get sick! In the same way, soil can get sick when we treat it badly. To keep soil healthy, we shouldn’t put anything into the ground or water system that kills the healthy bacteria in the soil. We should also make sure plants that are moved from one area to another are healthy in the first place so they don’t spread disease.
Diseases in soil can hurt or even destroy the plants growing there. If the soil is very wet or water can’t drain easily, fungi can invade plant roots and cause something called root rot. Plants with root rot turn yellow, drop their leaves, and eventually die.
WORDS to KNOW
root rot: when the roots of a plant rot, usually because of too much water.
One way diseases can get into plants is through their roots, but diseases can also affect the part of the plant that’s above the ground. This video shows how this happens, and how you can help protect your garden plants.
KEYWORD PROMPTS
tomato disease barrier 
An overload of salt in the soil can be just as bad. Have you ever tried to shake salt out of a damp saltshaker? Salt is very good at absorbing water, even underground. If salt absorbs too much of the water in the soil, the plants won’t have enough to grow.
Some insects and other animals living in soil are beneficial, but too many can cause damage to the plants. That’s why farmers are always trying to keep a balance of critters in their crops.
Things such as gasoline and pesticides should never be just dumped into the soil. Instead, they should be disposed of properly by reading the directions on the product label.
WASH UP!
Keeping the soil healthy is an important job we all share. The food we eat depends on the soil. Do you eat fruits and vegetables? The plants that produce them grow in the soil. Even your meat depends on healthy soil because meat comes from animals that eat the plants that grow in the soil. It’s important for the food chain that we are careful to prevent any diseases from starting and spreading.
Lisferia is a bacteria that lives in the soil. If listeria gets into food products, it can be killed with proper handling, cleaning, and cooking. If food isn’t handled properly, listeria can infect humans. In 2011, cantaloupes from Colorado were contaminated with listeria and people got sick.
WORDS to KNOW
pesticide: a chemical used to kill pests, such as insects.
food chain: a community of animals and plants where each is eaten by another higher up in the chain.
listeria: a bacteria that’s unhealthy for animals and people.
infect: when microbes invade your body and make you sick.
contaminate: to pollute or make dirty.
Food contamination can be prevented. The people who grow, handle, and serve food need to follow strict guidelines so that bacteria, such as listeria, don’t spread. And the good news is, most of the time everyone does follow the right procedures so you stay healthy. You can help make sure you and your family can eat worry-free by following some guidelines.
Wash fruits and vegetables under running water or scrub them with a clean produce brush before cooking, cutting, or eating them.
Store fruits and vegetables and uncooked meats away from each other in your refrigerator so they don’t touch or drip on each other.
Wash your hands, any utensils, and cutting boards before and after handling and preparing uncooked foods.
Clean all spills in the refrigerator and on the counters.
Make sure the meat you eat has been completely cooked.
Because our food comes from the soil, it is a very important part of our health! Soil is also important because some cures for diseases come from microorganisms in the soil. Let’s work together to make sure we have healthy soil for generations to come.
ESSENTIAL QUESTION
Now it’s time to consider and discuss the Essential Question: What would happen to our health if we had no soil?
BACTERIA FARM
Do you ever get tired of your parents saying, “Wash your hands!”? This project will help you see what happens if you don’t have clean hands when you handle food.
SUPPLIES
large potato or 2 small potatoes, peeled
clear plastic bags
marker
science journal and pencil
1 First, wash your hands and your potatoes. You want to start everything out as clean as possible. If you’re using a large potato, cut it into two pieces.
2 Wash your hands again. Handle one potato with your bare hands and drop it into a plastic bag. Write “clean hands’’ on the bag.
3 Play with your pet or go outside and play for a while. Then come back inside. Do not wash your hands! Handle the second potato and drop it in the bag. Write “dirty hands” on the bag.
4 Place both bags in a cool, dark place. Wash your hands! Start a scientific method worksheet.
5 In one week, check on the potatoes. Just look—don’t touch them or take them out of the bags. What do you see? Can you spot any black, green, or white fuzzy stuff? Which potato has more?
THINK ABOUT IT: Why are there more bacteria growing on one potato than the other? If there are bacteria even on clean food, why is it okay for us to eat this food? Is all bacteria bad?
HAND-WASHING EXPERIMENT
You’ve seen how washing your hands can help get rid of bacteria on your skin and food. But how much hand washing is enough? Start a scientific method worksheet, then try this quick experiment to see.
SUPPLIES
glitter or cinnamon
timer
soap
water
science journal and pencil
1 Put a little glitter or cinnamon on your hands. Rub it around so it’s spread on your skin. This is your pretend bacteria.
2 Set the timer for 30 seconds. Wash your hands with soap and water until the time is up.
3 Check your hands. Do you still have any glitter or cinnamon on them? Remember to check between your fingers and around your fingernails!
4 Set the timer for another 30 seconds and wash your hands again. Check your hands again. Keep washing your hands for 30 seconds at a time until your hands are completely clean. How long does it take? Record what you see in your science journal.
TRY THIS! Ask your parents for permission before you do this! Put glitter on your hands and, before washing, open a door with a doorknob. Have a friend or family member open the same door, then look at their hands. Is there any glitter on their hands? What does this tell you about how germs spread?