177 



These results are favourable towards the suitability of the soil for 

 irrigation, but, at the same time, had opportunity offered, it would have 

 been desirable to extend the investigation to a depth of three or four feet 

 lower down, for reasons already detailed in the manner illustrated above. 



DIVISION OF COLESBERG. 



The six soils from the farm Oorlogspoort, in the Colesberg Division,* 

 were also examined, with a view to ascertaining the proportions of soluble 

 salts present. These were found to range between '038 and '090 per cent., 

 and to average '058 per cent. Such amounts are not sufficient to be harm- 

 ful to plant life, even if the salts consisted entirely of sodium carbonate 

 or " black alkali/' the most injurious form in which alkaline salts are 

 fcamd in the soil. 



DIVISION OF BRITSTOWN. 



One of the first investigations into the possible alkalinity of lands 

 proposed to be irrigated was carried out in connection with the farm 

 Houw Water, in the Division of Britstown. Five sets of samples were 

 taken in almost a straight line, nearly a mile and a half from end to end, 

 from the lands intended to be irrigated below the site of the proposed 

 dam. In each case samples were collected in the manner already de- 

 scribed, to a depth of six feet. The physical nature of the soil may be 

 gathered from the following table : 



1st foot 



2nd foot 

 3-rd foot 



4th foot 

 5th foot 

 6th foot 



Fine loose loaru Fine loose 

 loam. 



Loose loam loose loam ... Loose loam. 



Stiff compact 

 clay. 



Stiff hard 

 clay. 



Stiff hard 

 clay. 



Very loose loam Very loose 

 loam. 



Rather stiffer ! 

 loam. 



Stiff hard clay 



Rather stiffer loam. 

 Looser loam. 



Loose loam ... j Moist loose loam. 



The approximate distances apart of the points whence these samples 

 were taken were as follows : 



Between A and B 430 yards. 



B C 250 



C D 850 



D E 900 



Time and circumstances did not permit of any thorough investiga- 

 tions into the depth of the water table below the surface, but as the aver- 

 age annual rainfall is very low only about 5 inches and as E was 

 the only one of the five probings which showed a suspicion of moisture 

 within six feet of the surface, there did not appear much probability of 

 a high water level in the subsoil. 



* See page 52. 



