Eroded soil has to go someplace.
In Africa it goes in the ocean. Go dig it up and put it back.
The Mississippi Delta is ALL eroded top soil. Go dig it up and put it back.
(You could use “Electric” backhoes. /s)
Hydroponics, who the hell needs DIRT.
Not one drop of water (except in the Tang the astronuts took into space) and not one speck of soil has left this earth since creation.
It’s probably going into the ocean. Good thing the ice caps are melting to keep the seas from getting completely filled with silt.