FERTILIZERS THE SOURCE, CHARACTER AND COMPOSITION OF USE FOR DIFFERENT CROPS AND CONDITIONS BY EDWARD B. VOORHEES, A.M. Director of the New Jersey Agricultural Experiment Stations, and THIRTEENTH EDITION New York THE MACMILLAN COMPANY LONDON: MACMILLAN & CO., LTD. 1910 All rights reserved Agric S 633 19 1910 AE PREFACE THERE is no question as to the desirability of the use of commercial fertilizers on most farms, though the methods now generally practiced are such as to indicate the very great need of a better understanding of what the functions of a fertilizer are, of the terms used to express their composition and value, of the kind that shall be used, and the time and method of application for the different crops under the varying conditions that exist. In the preparation of this book, therefore, it has been the aim of the author to point out the underlying principles and to discuss, in the light of our present knowledge of the subject, some of the important problems connected with the use of fertilizer materials. The subject is a large one when considered in all its bearings, and much must necessarily be omitted in a book intended for the general reader as well as the student. The author appreciates keenly his limitations, owing to the lack of definite knowledge on many vital points; yet it seems that at this time, when |