258 JOUIINAL OF THE DEPARTMENT OF AGRICULTURE. SePT., 1922. 



necessary supply of water. Hall also quotes one experiment which 

 showed that the amount of moisture in the top foot of a pasture was 

 found to be only half that present in the same depth of neig-hbouring: 

 uncropped land. 



When trees, however, have become firmly established and have 

 thrown out a ramified and elaborated system of roots to a considerable 

 depth, it is quite obvious that the tables will be turned, and a plania- 

 tion of such trees will deplete the sub-soil of so much moisture before 

 it is able to reach a shallow-rooted crop near the surface that the latter 

 is unable to obtain sufficient for its growth and well-being. Hilgard, 

 the great soil investigator, refers to the great draft made by the blue 

 gum (Eucalyjjtus globulus) upon soil-moisture in California, where, on 

 account of its rapid growth, this tree has been largely used for wind- 

 breaks. It was found that the trees deplete the adjoining fields of 

 moisture for about 30 feet on either side, so as to materially reduce 

 crops within that limit. For this reason he mentions that the pine 

 and the cypress have of late found greater acceptance for this purpose, 

 for the narrow types of leaves on these trees conduce to a minimum 

 amount of transpiration and loss of soil-moisture in contradistinction 

 to the action of the broad leaves of the gums. 



Moisture Experiments. 

 (1) First Eirperiinent, carried out at beginning of January, 1922. 



(2) Second E xjyeriment , carried out a fortnight later. 



Amount of Moisture. 



Yards Away. 



S fl 



H e^i 1 OP-, 



10 

 Yards Away. 



^ s 



20 

 Yards Away. 



a 





Percentage 

 Increase of 



Capillary 

 Water. 



First 9 inches 

 Second 9 inches 

 Third 9 inches 



lo-7 

 19-7 

 19-3 



18-2 

 20-1 

 20-2 



80 per cent. 

 41 



