LIST OF ILLUSTRATIONS 



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Tomatoes grown in poor sand, with and without manure 



Wheat grown at Rothamsted with varying quantities of 

 manure ........ 



Tomatoes with varying water supply 

 Tomatoes supplied with excess of manure 

 Tomatoes with varying manure and moisture supply 

 Curves showing weight of crop produced 

 Nobel's apparatus for sorting out soil particles 

 Murray's apparatus for the same purpose 

 Apparatus for determining carbon dioxide in chalk 

 Apparatus for collecting carbon dioxide from chalk in soil 



Apparatus for demonstrating the presence of carbon 

 dioxide in soil air ...... 



Brick chambers hned and floored with cement for experi 



ments with subsoil. Photo by Dr H. B. Hutchinson 

 Dongas in South Africa. Photos by Dr F. H. Hatch 



Alkali spot, Fremont, Nebraska. Photo by Dr F. J, 

 Alway ........ 



Curve showing amount of nitrate present in soil at 

 different seasons 



The drain gauges, Rothamsted. Photo by Dr H. B, 

 Hutchinson 



Distribution of rainfall in England and Wales . 



Distribution of wheat in England and Wales . 



Distribution of grass in England and Wales . 



Development of prairie land. Western Canada. Photos 

 by W. F. Oldham and by Staff at Indian Head . 



Crop map of Great Britain 



Types of furrow-slices ..,.. 



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