ADVANCES IN AGRONOMY VOLUME XI This Page Intentionally Left Blank ADVANCES IN AGRONOMY Prepared under the Auspices of the AMERICANSOCIETYOF AGRONOMY V O L U M E XI Edited by A. G. NORMAN University of Michigan, Ann Arbor, Michigan ADVISORY BOARD D. G. ALDRICH, JR. J. E. DAWSON W. H. FOOTE J. E. GIESEKING W. P. MARTIN R. W. PEARSON G. F. SPRAGUE H. M. TYSDAL 1959 ACADEMIC PRESS - NEW YORK and LONDON Copyright 0, 1 9 5 9 , by Academic Press Inc. ALL RIGHTS RESERVED NO PART OF THIS BOOK MAY BE REPRODUCED IN ANY FORM, BY PHOTOSTAT, MICROFILM, OR ANY OTHER MEANS, WITHOUT WRI'ITEN PERMISSION FROM THE PUBLISHERS. ACADEMIC PRESS INC. 111 FIFTHAVENUE NEWYORK 3, N. Y. United Kingdom Edition Published by ACADEMIC PRESS INC. (LONDON)Lm. 40 PALLMALL, LONDON SW 1 Library of Congress Catalog Card Number 50-5598 PRINTED IN THE UNITED STATES OF AMERICA CONTRIBUTORS TO VOLUMEXI DAVIDE. ANGUS,Department of Irrigation, University of California, Davis, California.* G. W. BURTON, Research Geneticist, Forage and Range Research Branch, Crops Research Division, Agricultural Research Service, United States Department of Agriculture, and the University of Georgia, College of Agriculture Coastal Plain Experiment Station, Tifton, Georgia. P. DOLL,Assistant Professor of Agriculturul Economics, University of Missouri, Columbia, Missouri. JOHN T . W. EDMINSTER, Assistant Chief, Eastern Soil and Water Management Research Branch, Soil and Water Conservation Research Division, Agricultural Research Service, United States Department of Agriculture, Beltsville, Maryland. D. L. GRUNES,Soil Scientist, Western Soil and Water Management Research Branch, Soil and Water Conservation Research Division, Agricultural Research Service, United States Department of Agriculture, Mandan, North Dakota. R. M. HAGAN,Chairman, Department of Irrigation, University of California, Davis, California. D. W. HENDERSON, Associate Professor of Irrigation, University of Calif ornia, Davis, California, and Associate Irrigationist, Agricultural Experiment Station, United States Department of Agriculture, Davis, California . L. W. HURLBUT,Chairman, Department of Agricultural Engineering, University of Nebraska, Lincoln, Nebrska. K. D. JACOB, Chief, Fertilizer Investigations Research Branch, Soil and Water Conservation Research Division, Agricultural Research Service, United States Department of Agriculture, Beltsville, Maryland. P. J. GAMER, Professor of Botany, Duke University, Durham, North Carolina. P. G. M E IJERS, Agronomist, Groningen, Holland. * On leave from the Division of Meteorological Physics, C.S.I.R.O., Australia. V vi CONTRIBUTORS TO VOLUME XI I-I. F. MILLER, JR., Chief, Harvesting and Farm Processing Resecrrch Branch, Agricultural Engineering Research Division, Agriculturul Research Service, United States Department of Agriculture, Beltsville, Maryland. ROBERTD. MUNSON,Agronomist, American Potash Institute, St. Paul, Minnesota. M . B. RUSSEU,Head, Department of Agronomy, University of Illinois, Urbana, Illinois. Y. VAADIA,Assistant Professor of Zrrigation and Assistant Zrrigationist, University of California, Davis, California. D. WWSMA, Assistant Professor of Agronomy, Purdue University, Lafayette, Indiana. PREFACE To serve as editor of this series is a rewarding experience on several grounds. In the past decade the editor has learned a good deal about agronomy and the ways of agronomists. Above all, however, he has had impressed on him a realization of the vigor of agronomic research, and of its accelerated pace. Investigators are abandoning empiricism and tackling head-on many of the tougher problems of soil science and crop science, frequently