CHAPTER X 



CULTIVATION 



So closely connected with irrigation as to be 

 practically 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. Cultiva- 

 tion destroys the small capillary tubes along which 

 the moisture passes through the soil into the atmos- 

 phere, and by thus forming a blanket of loose earth 

 on top, through which evaporation can only imper- 

 fectly take place, the lower layers of the soil are 

 kept moist. 



Another result of cultivation is that by checking 

 evaporation the formation of alkalis 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. 



