When the top soil has washed away or blown away—crop yields drop. Most farmers know this. But just why won’t the subsoil produce as well as the original top soil? Is there any particular element that we can add to eroded soils which will step up crop yields? These are questions we have been looking into at the Iowa Station.
Englehorn, A. J. and Bower, C. A.
"Eroded Soils Need Phosphorus,"
Farm Science Reporter: Vol. 5
, Article 2.
Available at: http://lib.dr.iastate.edu/farmsciencereporter/vol5/iss3/2