Published in Agron. J. 103:247–252 (2011) Published online 9 Dec 2010 doi:10.2134/agronj2010.0147s Copyright © 2011 by the American Society of Agronomy, 5585 Guilford Road, Madison, WI 53711. All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and ret...