36 THE farmers' handbook. 



White clay in a very fine state of division is distributed through the sand- 

 stone. 



The following analysis of a plastic, dark-coloured clay from Cook's Eiver, 

 may, perhaps, be taken as fairly representative of the clays of the Wiana- 

 matta shale formation: — 



Analysis of Clay from Cook's River — Representative of WianamatCa Shale. 



... absent 



•is 



... 1-71 



trace 



100-00 

 Average percentage of fertilising ingredients in Cumberland soils. 



Average of virgin soils from Wianamatta shale ... 

 Average of virgin soil from Hawkesbury sandstone 

 Average of all virgin soils from Cumberland 



The most striking differences in the two divisions of soils are the much 

 larger proportions of lime and potash, notably potash, in the shale soils and 

 the larger amount of phosphoric acid in the sandstone soils. The slight 

 difference in the nitrogen contents is not in reality due to the nature of the 

 rock, this constituent varying with the amount of organic mattter and humus 

 present in the soil, which averages 762 in the shale soils, and 7-22 in the 

 sandstone ones. 



Physical Characteristics. 



The soils examined vary from almost pure sand to stiff clays, and these are 

 fairly equally derived from both divisions of the county. They are, for the 

 most part, deficient in humus, and their capacity for water is low, the soils 

 from the sandstone formation being somewhat better off in this respect than 

 the shale soils. The possession of this property is important in enabling the 

 crop to resist the effects of a drought, and it depends chiefly upon the texture 

 of the soil and its content of humus. It is greatest in soils rich in humus, 

 marls (calcareous soils) coming next, clays, loams, and sandy soils being 

 lowest. 



With these exceptions, which are due to deficiency in lime and humus, 

 the physical nature of our soils does not present any feature of particular 

 note. 



Defects due to want of Lime. 



As has been pointed out above, want of lime is the most serious defect in 

 these soils, and in quite seven cases out of ten of the soils examined, the 

 advisability of liming is strongly insisted upon. 



The most apparent result of deficiency in lime is the tendency to sourness, 

 [f not actually sour, practically all the soils in this county have a strong 

 tendency to become so after a short time. This may be due in some cases 

 to deficient drainage, but it is also evident in well-drained soils, and in dry 

 weather, and does not appear to be much improved by cultivation as it 18 

 usually practised. 



