UNITED STATES DEPARTMENT OF AGRICULTURE 



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BULLETIN No. 353 



Contribution from the Bureau of Plant Industry 

 WM. A. TAYLOR, Cliief 



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Washington, D. C. 



PROFESSIONAL PAPER 



March 16, 1916 



MOISTURE CONTENT AND SHRINKAGE OF FORAGE AND 

 THE RELATION OF THESE FACTORS TO THE ACCURACY 

 OF EXPERIMENTAL DATA. 



By H. N. ViNALL, Agronomist, and Roland McKee, Assistant Agrostologist, Office of 

 Forage-Crop Investigations.^ 



CONTENTS. 



Introduction 



General plan of the experiments 



Use of samples in correcting forage yields 



Relation of the stage of growth of forage plants 

 to their moisture content 



Loss of moisture in forage during the early- 

 stages of curing 



Page 

 Variation in the moisture content of growing 



alfalfa during a single day 31 



Moisture content of baled hay 31 



Shrinkage of hay after storing and variation in 

 weight due to changes in atmospheric hu- 

 midity 32 



27 Summary. 



36 



INTRODUCTION. 



Agronomic literature contains but little in the way of well-planned 

 investigations on the subject of the moisture content of different 

 forage plants either green or cured, a matter which is intimately 

 related in farm practice to the proper handling and wise marketing 

 of forage crops and in investigational work to the correct interpreta- 

 tion of yield data. This subject is of sufficient importance to justify 

 much more attention than has previously been given to it by experi- 

 menters. Careful investigators have long recognized that many of 

 the published data on forage crops are inaccurate, on account of the 

 uncertain amount of water included in the yields. 



The term "air dry," as used in the investigations described in the 

 following pages, refers to that stage of curing when the humidity of 

 the forage and the humidity of the atmosphere have reached a state 

 of equilibrium. The percentage of moisture in the forage when 

 air dry of course varies with the changes in atmospheric humidity, 



1 Messrs. W. J. Morse, H. L. Westover, M. W. Evans, A. B. Cron, and R. E. Getty, members of the 

 staff of the Office of Forage-Crop Investigations, have contributed quite largely to this publication by 

 their assistance in collecting and preparing records of the numerous samples required. 

 21216°— Bull. 353—16 1 



