14 Jan 1994
Since you seem to prefer personal interviews to reference materials,
I spoke with Diana (my cousin) about this while I was home for Christmas.
Farmers refer to topsoil depth as tillage. They are very concerned about
it, measure it frequently, and take steps to maintain it. Diana said
what I already said: there is no net loss of topsoil occurring. She told
me something that I did not know: flooding is actively bad for the soil.
It leeches nitrates. When the flood waters receeded my uncle was anxiously
testing the soil to see how much damage was done. Fortunately, it appeared
to be minimal in his case. In the case of flooding, the point is that
farmers are naturally going to do what is best. If they could actually
improve yields (including long run yields based on saving the soil), they
would arrange to flood their fields.