William W. Simpkins

Improving Recycling with an Existing 83% Diversion Rate: Solving Iowa State University’s Recycling Enigma

Kevin Daniel Marquardt, William W. Simpkins, Merry Rankin, 2011 .

Theme Overview: Agriculture and Water Quality in the Cornbelt: Overview of Issues and Approaches

Matthew J. Helmers, Thomas M. Isenhart, Mark D. Tomer, 2007 .

Evaluation of tillage and crop rotation effects on groundwater quality—Nashua project

Thomas S. Colvin, Douglas L. Karlen, William W. Simpkins, 1994 .

Water Quality in Walnut Creek Watershed: Nitrate‐Nitrogen in Soils, Subsurface Drainage Water, and Shallow Groundwater

Jerry L. Hatfield, Cynthia A. Cambardella, Timothy B. Parkin, 1999 .