31 



CHAPTER IX. 



CULTIVATION. 



So closely connected with irrigation as to be prac- 

 tically a part of it is the subject of cultivation. The 

 irrigation of a piece of land is of little use unless it is 

 followed by cultivation, as the water poured into the 

 soil soon evaporates unless the surface of the ground 

 is kept well stirred. Cultivation destroys the small 

 capillary tubes along which the moisture passes 

 through the soil into the atmosphere, and by thus 

 forming a blanket of loose earth on top, through 

 which evaporation can only imperfectly take plaQe,. 

 the lower layers of the soil are kept moist. 



Another result of cultivation is that by checking 

 evaporation the formation of alkalies on the surface 

 of the ground is prevented. 



In arid regions, such as the greater portion of the 

 Murray Valley consists of, the rainfall has never 

 been sufficient to leach much of the natural salts 

 out of the land and to carry them away in the river 

 water. When this land is irrigated some of the 

 salts are dissolved by the water. Capillary action 

 draws the salt-impregnated water to. the surface of 

 the ground, where the water is evaporated and the 

 salts left as a residue. As some of these salts are 

 highly detrimental to plant life, being especially 

 injurious when concentrated on or near the surface 

 of the ground to the crown and surface roots of 

 fruit trees, it is necessary, were it only for this 

 reason alone, that the work of cultivation in the 

 orchard should be of a thorough nature. 



