iv.] HUMUS AND SOIL WATER 131 



bound during the long winter, and the wheat is spring 

 sown; sheep are not kept because of the cold, but 

 otherwise the routine of cultivation is identical. The 

 Australian is generally content with ploughing the 

 bare fallow repeatedly ; in America the methods are 

 a little more elaborated, and subsoil packers, followed 

 by disc harrows and other surface cultivators, are 

 employed in order to conserve moisture and prevent 

 evaporation, by maintaining a firm substratum and 

 a live surface. These simple principles of dry farming, 

 founded upon the practice elaborated in the drier 

 districts of the south and east of England, have enabled 

 vast tracts of otherwise scanty grazing country to be 

 brought under cultivation. The details of the methods 

 to be followed, and the crops that can be grown, are 

 being made the subject of careful investigation, now 

 that the better farming lands are all taken up, and new 

 settlers are being forced on to what before were ranching 

 areas or regarded as bad lands. What are wanted are 

 crops with a low transpiration coefficient, which elaborate 

 a maximum of dry matter for the water they consume, 

 or again, cereals with a high migration ratio, which 

 transform a comparatively high proportion of their total 

 dry matter into grain, 



Effect of Dung on the Retention of Water by the Soil. 



A soil which has been enriched in humus through 

 repeated applications of farmyard manure will resist 

 drought better than one in which the humus is low ; the 

 difference is seen not so much in the greater amount 

 of moisture present in the soil containing humus, as 

 in the way it will absorb a large amount of water 

 temporarily during heavy rainfall, and then let it 

 work more slowly down into the soil, thus keeping 

 it longer within reach of the crop. Good examples 



