10 



(common salt), sodium sulphate (Glauber's salt), 

 and magnesium sulphate (Epsom salts) are highly 

 detrimental to all varieties of citrus trees. There- 

 fore, land likely to develop alkali trouble, such as 

 shallow soils under 3 feet in depth resting upon 

 limestone, or upon a hard or tenacious subsoil, should 

 be avoided by the planter. However, as the presence 

 of alkalies in a soil is due to defective under drainage 

 by choosing deep land, with a loose subsoil, no 

 damage from alkali trouble should be experienced. 



SITUATION NOT SUBJECT TO HEAVY FROSTS. 



Although, on the whole, severe damage to citrus 

 trees due to frosts is but a rare occurrence on the 

 Murray Valley irrigation settlements, there are yet 

 certain situations subject to comparatively heavy 

 frosts which should be avoided by the planter. 



It is a matter of common observation that frosts 

 are the most severe in valleys, hollows, and low 

 areas, while the adjacent hillsides or elevated lands 

 remain comparatively untouched. This is because 

 the cold air from the hillsides, being heavier, drains 

 off into the lower levels and settles there, while the 

 warm air rises to replace it. This interchange of air 

 continues until frost occurs in the lower levels, while 

 the higher lands escape. 



. A citrus grove should, therefore, never be located 

 in a hollow, basin-shaped depression, or in a narrow 

 gully. 



THE IDEAL POSITION. 



The ideal position of a citrus grove is on a slope 

 facing the east, as experience has shown that the 

 rays of the rising sun are less injurious to frosted 

 plants than they are if the sun is some distance 

 above the horizon before it strikes them ; while the 

 slope of the ground will allow the cold air to drain 

 off into lower levels. Of course, a situation facing 

 the east, although desirable, is not essential for the 

 location of the grove, the one thing necessary being 



