Hello Mr. Patton. At my school in Colorado we must do a project about a theoretical civilization that's been hit with a problem. For us, our topsoil has been washed away and we were wondering if you could help us. Our solution is making mass, efficient composting machines along with building to help divert water from the topsoil being farmed on. We wanted to know if these solutions would work and if not how to fix it. Thank you.
I am not sure of all the constraints of the problem but will throw a few things out for consideration.
Soil is not just organic matter, but minerals too. A soil profile usually includes a humus layer, what your compost will replace, but also a layer of loam a mix of sand and clay and silt, and ultimately a layer of clay. In mature soils, the clays migrate downward and form layers deeper in the profile.
So in your construction you might add a step whereby you pulverize underlying rock,to increase the surface area of the particles so that they can begin to break down into their mineral component parts making the minerals available for plant uptake. Churn the pulverized rock up, and mix in some compost followed by a final layer of compost. The humic acid form the compost will accelerate the weathering and breakdown of the pulverized rock and underlying bedrock.
This mineral weathering will require water, so if you intent in your construction phase was to protect your new soil from erosion, you might consider an impoundment for erosion control and irrigation.
There was a time when farmers in the US did not pay much attention to topography and would just plow straight rows no matter what the slope or orientation of the land was. This promoted erosion. They solved the problem by contour ploughing, they followed the curves of the topography like the lines on a contour map, and that way the rows and furrows were always perpendicular to the direction of the flow of the runoff and it prevented erosion of the ploughed fields.
So you might want to add that as part of your improvement plan, call it Improved Farming Practices. Another method is no till farming where each successive planting is done below the ground without ploughing the preceding years stubble. This keeps the soil intact and the previous years roots help keep the soil from eroding.
I hope this helps.