Have you ever seen cow patties the size of Frisbees? Or the little droppings from chickens?

Over time, this waste adds up. In fact, if you could pile up all the livestock manure that’s produced in the United States in a year, it would weigh 350 BILLION pounds! You can see why lots of scientists are tackling this messy problem.

What do we do with all of this poo?

Farmers can use manure to fertilize their fields. Animal droppings might not look or smell pretty, but they contain important nutrients that plants need to grow. Farmers spread their animals’ waste onto fields for the same reason that kids take vitamins to grow big and strong.

But there aren’t enough fields for all the waste that’s produced by animals. In fact, if too much manure is plowed into the soil, it can slide from hillsides and trickle into streams. This pollution can harm animals and people who depend on fresh, clean water.