ItJ Journal of the Department of Agriculture. 



irrigation. For example, a water described in the north-west as 

 lekker vars water " was found on analysis to contain no less than 

 89 parts of sodium carbonate per 100,000 parts water, an amount 

 which would cause considerable injury if applied to a stiff soil or even 

 to a fine sandy loam. 



Again, there are farmers who would not regard a soil as brak 

 unless it were visibly so. A soil may, however, be white at the surface 

 with a certain kind of brak and yet produce good crops, while a 

 quantity of another kind of brak insufl&cient to be visible would cause 

 much more harm. 



There are others who, regardless of taste, consider any whitish 

 appearance on the surface of the soil (especially if this resulted after 

 water had run over it) as brak ; there are. those who describe any land 

 now bare, but formerly clothed with vegetation, as brak land, whereas 

 it may or it may not be brak. Frequently, and often with truth, 

 permanently wet land is described as brak, whereas it may not be 

 t)rak. 



In the Karroo waters are frequently described as brak which are 

 really only rather hard ; presumably on account of the whitish residue 

 they leave behind on natural evaporation. Then, again, certain 

 muddy waters are sometimes stated to be brak, presumably because of 

 the shiny paint-like coating of silt they leave behind them, whereas 

 no water that is brak in the sense that it is salty would leave siich a 

 deposit. 



Enough has been said to indicate the need for a standard meaning 

 of the term " brak;" The meaning attached to the term in this paper 

 and the one which, if I may presume to say so, should be adopted 

 generally is that condition of a soil or of a water in which, for agri- 

 cultural purposes, there is an excess of any kind of salt. This 

 meaning is practically the meaning assigned to the term " alkali " in 

 America or " usar " in India, when used in reference to soil. 



Included in the teirtn "salt" in the above definition are common salt 

 (sodium chloride), glauber salt (sulphate of soda), carbonate of soda, 

 bicarbonate of soda, nitrate of soda (Chili saltpetre), the corre- 

 sponding- salts of potash, epsom salts (sulphate of magnesia), and 

 others. The commonest constituents of brak are one or more of the 

 first four. 



Of these the most feared is carbonate of soda, the least feared 

 sulphate of soda. It is this latter salt with which the soil may be 

 white and yet produce crops. It is the misfortune of the Union that 

 a very large proportion of its waters which are available for irrigation 

 contain more or less carbonate of soda, usually in the form of bi- 

 carbonate of soda, however. 



The Origin of Brak in Inland Soils. 



Lands close to the sea are brak because the sea water has rendered 

 them so ; but the occurrence of brak lands hundreds of miles inland, 

 and at altitudes of several thousand feet above sea-level, cannot be 

 explained in this way. 



It will be found that wherever brak lands occur inland the annual 

 rainfall is low — usually less than 2 inches. 



Now in the natural course of events salts are continuously being 

 formed in the soil through certain natural agencies, as, for instance. 



