The world’s soil is in trouble. Ecologists say without dramatic changes to how we manage land, vast swathes of grassland are at risk of turning into hard-packed desert. To make sure that doesn’t happen, researchers are testing out innovative ways to keep moisture in the soil.

In eastern Colorado, one way could be in the plodding hooves of cattle.

Conventional wisdom tells you that if ranchland ground has less grass, the problem is too many cows. But that’s not always the case. It depends on how you manage them, if you make sure they keep moving.