362 



Journal of Agriculture, Victoria. | K) June, 1918. 



be achieved through constant and strenuous effort. Of these details 

 none can be regarded of greater importance than the cultivation con- 

 tingent on irrigation. When the surface of the soil dries after each 

 watering, it cracks, and the fissures act as capillary vapour ducts 

 through which the moisture is drawn off into the air. 



The more tenacious the soil the greater will be the extent of the 

 cracking, especially in the irrigation furrows and in slight depressions 

 on the surface of which undue water lodgment occurs. Before the 

 necessary cultivation after each watering can be satisfactorily accom- 

 plished, it is essential that the soil should have assumed a fairly dry 



Plate 169. — Cross-section of Supply Channel showing position 

 of Outlet Pipe. 



Surface 



Level 



Plate 171. 

 Fig. 1. — Arrows represent downward percolation of water from furrows. 

 Fig. 2. — ^Arrows represent moisture being brought to the surface by capillary 

 attraction. 



state, and it is preferable that this condition should accrue from good 

 drainage rather than from capillary action and evaporation. 



A.part from the matter of cultivation at this time it should be 

 remembered that the feeding roots are most active when there is just 

 the proper percentage of moisture present, and that they suffer from 

 excessive water to a degree corresponding with the duration of the soil's 

 saturation. On the other hand, the healthy growth of the trees is 

 retarded through lack of the essential solution in dry soil during the 



