It may seem as if dirt is everywhere, with plenty to go around forever. But it's actually disappearing fast.
"If we don't take care of the soil, which is just the first five centimeters layer of life that is on the earth, our future is totally condemned," said UC Berkeley Professor Miguel Altieri, Ph.D.
That UC Berkeley professor is part of a documentary trying to warn people dirt is under attack.
The documentary highlights threats to farmland all over the world, but there's a lot to be concerned about right here at home.
The dirt we need to grow food is being mistreated and getting used up.
We talked to documentary producer and environmentalist Gene Rosow by satellite from Los Angeles.
"Gene, how big a problem is this really?" asked ABC7's Dan Ashley.
"Agriculture systems will collapse and we will not have the defenses we need to deal with the consequences of climate change unless we take care of dirt. So it's a huge, huge problem," said Rosow.
That may sound alarmist. But Ron Amundson, UC professor of soil science agrees, the way we treat dirt is affecting global warming.
Cal has been ground zero in soil research since the late 1800s.
About 20 percent of all this carbon dioxide that is getting into the atmosphere is actually due directly or indirectly to agriculture," said Professor Amundson, Ph.D.
Amundson says plowing fields stirs up micro-organisms in the soil. That puts carbon dioxide into the air - and adds to global warming.
Another major issue is erosion. When dirt is left bare during farming over time, the soil is blown away by wind and washed away by water and with it, go critical nutrients.
"This is an emergency because we only have a small amount of land to raise food crops and if it's eroding and losing its carbon, what are we going to do for food," said soil specialist Bob Shaffer.
Shaffer is working on these problems at farms in Napa and Sonoma.
He says we need to completely re-think the way we grow things. Instead of plowing, Shafer uses other methods to prepare the soil.
He uses compost made from food scraps. That adds nutrition to the soil and keeps it soft for planting.
"Right out here where we put a lot of compost, you see earthworms, this is a very positive sign of soil health," said Shaffer.
Shaffer also uses cover crops - extra plants mixed in with the main crop. They prevent erosion and the diversity of vegetation adds even more nutrients.
"Whereas it could be called a weed, there's no reason for this to be considered a weed because it's actually benefiting the soil below ground and the soil above ground," said Shaffer.
In addition to keeping soil healthy, another issue is keeping it from getting paved over.
At UC Berkeley for example, there used to be lots of dirt, but not anymore.
"I've walked across the entire campus, I think this is about the most pristine spot in the Berkeley campus," said Professor Amundson, Ph.D.
Professor Amundson is talking about the little ring of dirt around this oak tree.
"If we look at the soil that lies underneath the leaf material, we can see this really nice organic matter- rich surface layer," said Professor Amundson, Ph.D.
This kind of virgin dirt is critical to keep the planet healthy. But an environmental group called the Open Space Institute says the United States is losing more than a million acres of both farms and open space every year.
Most of the land is cleared to make way for development projects such as parking lots, shopping malls and new housing.
That's two acres of open land disappearing every minute, every day.
Scientists have been trying to focus public attention on dirt for some time, but soil just isn't very sexy. So now they're hoping the new documentary will grab the spotlight.
"Do you think with Dirt! The movie you can hit pay dirt?" asked Ashley.
"Pay dirt for us would be showing it at Congress, at the White House," said Rosow.
And in local communities, to get people to understand dirt is critical to our very survival.
Dirt! The Movie won't be in theaters until next fall, but there is a preview showing at UC Berkeley next week.
Written and produced by Jennifer Olney.