iv.] ROLLING 107 



feet or more, but maintains the surface soil, sampled 

 only down to 1 8 inches, in a moister condition. 



Depth of Sample. 



Down to 18" . 

 Down to 24" . 

 Down to 36"- 54" 



Percentage of Water. 



Boiled Ground. 



15-85 

 19.49 

 1872 



Unrolled Ground. 



15.64 

 19-85 

 19-43 



Since rolling dries the soil as a whole, it is only desirable 

 when shallow-rooted crops must be kept supplied with 

 water at any cost ; as soon as they get their roots down 

 hoeing should begin to diminish the inevitable evapora- 

 tion from the firm surface. Thus a tool like the old 

 broadsharing plough, still used on the chalk, is particu- 

 larly valuable in preparing a tilth for roots, for, while 

 creating a loose surface tilth, it is consolidating the soil 

 below and increasing its power of lifting water from the 

 subsoil. 



Similarly, in the semi-arid regions of Western 

 America and in Australia, where the rainfall is barely 

 sufficient for the needs of the crop, in the preparation of 

 the land great importance is laid on the two operations 

 of "subsoil packing," and "the establishment of a soil 

 mulch." This is the equivalent of the English practice 

 of preparing a seed bed for roots ; frequent cultivation 

 without inverting the soil to work it down to a fine 

 tilth, constant use of the ring roller or subsoil packer to 

 consolidate this crumb until it will lift water by capillarity, 

 and finally the production and continual renewal by 

 means of light cultivators or horse hoes of a very thin 

 skin of loose soil on the surface. 



Valuable as the operation of rolling is on grass 

 land in the early spring, in order to consolidate the soil 



