Manurial Needs and Resources. 155 



Though doubtless the phosphoric acid would be largely present 

 as phosphate of iron, and therefore not readily available, it might 

 form a cheap and useful manure. 



The night soil of some of the compounds on the Rand is treated 

 so as to render it odourless by heat. The so-called " ash " left was 

 found to contain : — 



If the product can be produced in large quantities, and equal to 

 the sample, it should find a ready sale as a fertiliser. 



From the above account it will be seen that the natural sources 

 of phosphates in this Colony are limited, and in many instances it 

 may be necessary to purchase imported materials. Superphosphates are 

 well suited for such of our soils as contain, say, one per cent, or more 

 of lime as carbonate, but with the great majority of our soils, poor 

 as they are in lime, basic slag or " Thomas phosphate " will probably 

 be the best form of phosphatic manure. 



3. — Lime. 



Fortunately, of this important substance, the Colony has large 

 natural resources. Quantities of limestones, some of great purity, 

 exist in many districts, and though I believe that it is true that a 

 large proportion of the lime commerciably obtainable is of poor 

 quality, being badly burnt and containing much insoluble matter and 

 magnesia, this could be easily remedied by proper management, and 

 the choice of suitable limestone. 



We have examined many specimens of limestones, and among 

 them were some of excellent quality, capable, if properly burnt, of 

 yielding lime admirably suited for agricultural purposes. 



As typical examples of such pure limestones, though it is, 

 perhaps, more correct to describe some of them as calcite, but of 

 which large deposits are said to be available, I may quote the follow- 

 ing analyses : — 



99.9 99.9 99.8 99.89 



