Healthy topsoil contains lots of living organisms. Those organisms are made of carbon. When we "lose" topsoil, those organisms die, and much of their carbon is released into the atmosphere. Burning fossil fuels also adds carbon dioxide into the air, but since 1850, twice as much carbon dioxide has been released into the atmosphere by agriculture than by fossil fuels.
How do we lose topsoil? By erosion.
Every time a field is plowed, it exposes the topsoil to wind and rain.
When the same field is covered in grass, the loss of topsoil is almost
nil. Rain is absorbed rather than running off as mud, and wind doesn't
blow the dirt into the air. A healthy grassland creates more topsoil
than it loses, pulling ever more carbon from the air and sequestering it underground.
can we produce food without tilling the ground? One very important way
is by using grazing animals. They eat the grass, and the way their
hooves break the ground and the way their waste nurtures the grass, if the grazing is done properly,
that grassland will become more productive, turning more of the
sunlight into food — without losing topsoil and without contributing
carbon dioxide to the air. In fact, by making the grassland so healthy,
the net effect is to considerably reduce the carbon dioxide in the air.
When the soil is cared for in this way, not only do we reverse the loss of topsoil, but we also prevent water shortages, feed wildlife, and create greater biodiversity.
Read more: How to Stop Grasslands From Turning Into Deserts.