Prepared by
Philip W. Westerman, Professor, Department of Biological and Agricultural Engineering
Karl A. Shaffer, Extension Associate, Department of Soil Science
J. Mark Rice, Extension Specialist, Department of Biological and Agricultural Engineering
College of Agriculture & Life Sciences
North Carolina State University
The use of trade or brand names in this publication
does not imply endorsement of products mentioned
or criticism of similar products not mentioned.
Copyright (c) 2008 by North Carolina State University
Published by
North Carolina Cooperative Extension Service

![]()
![]()
Distributed in furtherance of the acts of Congress of May 8 and June 30, 1914. North Carolina State University and North Carolina A&T State University commit themselves to positive action to secure equal opportunity regardless of race, color, creed, national origin, religion, sex, age, veteran's status, or disability. In addition, the two Universities welcome all persons without regard to sexual orientation. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating
AG-639W E09-51800 (Revised, August 2008) BS