What is dirt made out of? - Big Questions (Ep. 15)

Hi, I'm Craig. I'm a dirty, dirty man, and this is Mental Floss on YouTube

Today I'm gonna answer Callie Waddle's big question. What is dirt made out of

Well, Callie, not to get all know it all on you, but I'm going to assume you mean soil instead of dirt

Soil is the top layer of the earth where plants can grow. Most people use dirt and soil interchangeably, but scientists don't consider them synonyms

Dirt is the loose soil, so it's no longer a part of that layer and no longer supporting plant life

Plus, they can refer to a whole mess of other things. Get it. Now that we have that all figured out, let's get dirty. Started

So soil is formed when rocks underground come in contact with water, like rainwater, or when I pour one out for my homies

Over time, those rocks break down into smaller minerals like quartz, mica, and calcite

As organic material breaks down, it also contributes to soil formation. Around 45% of the soil that's formed is made from three main properties, sand, silt, and clay

25% is water, 25% is air, and 5% is miscellaneous or. organic material like plant debris. But what are all of those things made out of you

ask? As for chemical elements, oxygen is extremely abundant in soil. Some other

elements commonly found are phosphorus, nitrogen, potassium, silicon, aluminum, iron calcium magnesium sulfur sodium and that gopher from caddyshack I sure you noticed that I being pretty vague about this That because soil differs from place to place It not always the same which means it probably doesn always consist of the same stuff

In the United States alone, there are around 50,000 different types of soil, and that's just in my laundry basket

These differences are due to five factors. Climate, parent material, topography, organisms, and time

All of that in my laundry basket. Basically, soil in the tundra is going to be different from soil in the desert

which is going to be different from soil in the prairie, which is going to be different from soil in..

One interesting way to examine how soil varies is by looking at the soil's pH, which helps determine which plants will thrive in that soil

pH is greatly affected by things like climate and rainfall. Soils with low pH tend to have less macronutrients, whereas soils with high pH tend to have less micronutrients

In the western U.S. soil is more alkaline, whereas on the east coast and in the Pacific Northwest, it's more acidic

So if you're especially curious about the soil in your area, one way to find out more is to pH test it, or test it

You can buy soil testing kits for pretty cheap at a hardware store. In addition to pH levels, many of these will tell you

you how much nitrogen, phosphorus, or potassium is in the soil. Another good way to test

out the soil is to roll around in it. Thanks for watching Mental Floss on YouTube made

with the help of these filthy, filthy people. If you have a question of your own, leave it

in the comments. I will see you next week. Hopefully after I've showered, after rolling around

in the dirt. The soil