CONTENTS. 
Page. 
Introduction 9 
Effect of soil factors on the water requirement 11 
Effect of soil-moisture content on the water requirement 11 
Il'enkov's experiments 11 
Fittbogen's experiments 12 
Hellriegel's experiments 13 
Maercker's experiments 13 
Schroeder's experiments 14 
Von Seelhorst's experiments 14 
Wilnis's experiments 15 
Daszewski's experiments 15 
Fortier's experiments 15 
Von Seelhorst and Biinger's experiments 16 
Ohlmer's experiments 16 
Wimmer's experiments 16 
Preul's experiments 18 
Widtsoe's experiments 19 
Leather's experiments 20 
Kiesselbach's experiments 20 
Kiesselbach and Montgomery's experiments 21 
Pfeiffer, Blanck, and Flugel's experiments 22 
Conclusions 24 
Effect of soil type on the water requirement 25 
Marie-Davy's experiments 25 
Liebscher's experiments 26 
King's experiments 26 
Von Seelhorst's experiments 27 
Widtsoe's experiments 27 
Leather's experiments 28 
Conclusions 28 
Effect of cultivation on the water requirement 28 
Sleskin's experiment 28 
Widtsoe's experiment 29 
Conclusions 30 
Effect of the soil mass on the water requirement :->0 
Hellriegel's experiments 30 
Leather's experiments 30 
Conclusions 31 
Effect of fertilizers on the water requirement 31 
Soil cultures 31 
Lawes's experiments 31 
Marie-Davy's experiments 32 
Hellriegel's experiments 33 
Deherain's experiments 34 
King's experiments 34 
285 5 
