Chemical Analysis of Soils. Ml 



It will be uotieed that uotliing has .been learnt regarding the 

 suitability of the soil for any particular crop or crops. There are 

 other factors which must be known before any opinion can be 

 expressed. Since the soil is probably heavy, and the samples analysed 

 are also always examined as regards texture, when this will have been 

 confirmed, it is probably well suited for cereals, including wheat. Tlie 

 * farmer wiould, however, be rather annoyed if he were advised to grow 

 wheat on the land from which this sample came as it is situated in 

 the Transvaal, in the region of summer rainfall, and cannot, at least 

 at present, be irrigated. If a soil sample can be identified as the 

 same or as similar to one already well known, provided climatic con- 

 ditions are similar, the most suitable crops can be suggested. This 

 may occur in perhaps 10 per cent, of cases, one of the chief reasons 

 why better information is not available being that farmers seldom 

 trouble to determine what crops are most suited to the special condi- 

 tions obtaining on their farms. As a general rule the South African 

 farmer sets out to grow some crop or other, maize, let us say, and 

 maize he grows, though it may pay him far better to grow some- 

 thing else. It is this lack of experiment on the part of farmers which 

 renders it so difficult, verging on the impossible, to advise as to the 

 most suitable crops. With some crops, and notably with forest trees, 

 it is climate, not soil, which is the determining factor in the 

 suitability for any particular locality. IVot that soil conditions must 

 be ignored, but they are in many cases only a secondary considera- 

 tion. 



To return to our soil, we may say that, quite apart from the 

 irrigation question, it is unsuitable for lucerne on chemical grounds, 

 owing to the small percentage of calcium carbonate ; that it is probably 

 too heavy for successful potato growing; and that the soil is suited 

 to cotton and sugar-cane. It is to be noted that of the above conclu- 

 sions only one, that the soil is unsuitable for lucerne, is dediiced 

 from the chemical analyses. The others are dependent on the texture. 

 It must also be particularly noted that of the crops for which the 

 soil is said to be suited the possibility of cultivating cane and wheat 

 are also dependent on conditions quite extraneous to the soil itself, 

 namely, climate and water supply. 



Of course the soil is suitable for growing any of the commoner 

 and less specialized farm crops; maize, teff, oats, barley may be 

 successfully grown on a great variety of soils. 



If the complete chemical analysis of a soil furnishes so little 

 information as to crops it follows that a partial analysis wall furnish 

 less. The partial analysis carried out by the Division of Chemistry 

 must not be expected to furnish any information other than a basis for 

 suggesting a scheme of manuring. We learn from the foregoing 

 partial analysis that the soil is well supplied with lime, with potash, 

 and fairly well with both nitrogen and phosphoric oxide. Green 

 manuring and the application of some phosphatic manure should 

 form the basis of the system of maintenance of fertility. 



The Farmer's Part. 



It must not be supposed from what has been said that soil analysis 

 is altogether without value. A value it certainly has if properly con- 

 sidered, but it must not be looked upon its a sort of magic touchstone 



