Role of nitrogen, phosphorus and potassium fertilizers in continuous corn culture on Nicollet and Webster soils /
Englehorn, A. J.,author.
Pesek, John T.,author.
Shrader, W. D.(William Duncan),author.
Iowa State University.Agricultural and Home Economics Experiment Station.
Iowa State University.Department of Agronomy.
Title from front cover.
Includes bibliographical references (page 18).