How long does it take new soil to form and why we should be concerned about losing soil to erosion?
It takes 500-1,000 years to create an inch wide horizon of soil (depending on the climate). Soil erosion causes infertile land, sedimentation in waterbodies, and negative changes to natural geogrpahy.
Climate is often the deciding factor is how long it takes to form soil. In temperate climates, it can take 1,000 years to create a inch-wide layer of soil, but it could take as little as 500 years in a rainy, tropical climate to create the same thing. To make soil fertile enough, it can take thousands of years to acquire minerals from parent soil, rock, organic matter, etc.
Soil erosion creates a big impact on the majority of the agricultural sectors around the world. Erosion will decrease the fertility present in soil, making hefty harvest difficult and a meal and a profit for those who depend on agricultural work even more so. Soil is considered a non-renewable resource because once it's gone, retaining it is nearly impossible and it'll take centuries for it to return in proper shape. Deteriorated land has a tendency to not absorb enough water, which can result in flooding.
The impact on streams can cause clogs, making it more difficult to maintain healthy numbers of live fish in the water. Fish can also be a source of food and profit for other people as well, making this a difficulty for both fishermen and agricultural farmers.