718 VARIABLE CHARACTER OF VEGETATION ON BASALT SOILS, 



being lapidl}^ removed by streams and rain-torrents on the steep 

 slopes, are fairly shallow and stony, well drained and porous,, 

 hence a healthy forest-vegetation has been able to establish itself. 



E. — The Basaltic Bogs oi plains and tablelands owe their want 

 of a forest-flora to inefficient drainage. The soil is water-logged 

 and the soil- water is charged with salts which are detrimental. 

 The roots of trees would get suffocated and would rot. 



It will be seen from the above account that the defect of 

 basaltic soils is never want of plant-food. The worst faults are 

 high water-capacity, which causes the drowning of plants in wet 

 weather; and the low capillary power, which impedes a renewal 

 of soil-moisture in droughty seasons. Silicious soils lose their 

 moisture quicklj" enough, but they are able to get supplies from 

 the subsoil, because of their high capillary power and porosity. 



Chemical Composition of Basalt-Soils. 



The following table gives some idea of the comparative value 

 of different soils, based on their mamuial ingredients (Table i.). 

 The richness of the basalt soils is indisputable, and it is only 

 their mechanical condition which is adverse to always getting 

 good results. They must be kept in a continual state of aeration 

 by frequent })loughing, and an}^ cereal croiis which do not root 

 too deep will flourish on them. The addition of substances which 

 will increase the capillary power, such as sand and sawdust, can 

 always be employed to improve the texture of heavy basalt soils. 

 The Richmond Eiver volcanic soils, whose average composition 

 has been calculated by Mr. Guthrie,* will be seen to be rather 

 poor in potash as compared with the other basaltic soils. This is- 

 due to the dense vegetation in the Northern Rivers district. Th& 

 sandy soil from the Pilliga scrub, which is covered with a dense 

 pine jungle, is likewise deficient in potash as compared with 

 Hawkesbury Sandstone soil. 



Although basalt-soils are generally of good quality, they may 

 in certain situations be reduced b}^ leaching to the condition of 



* Agricultural Gazette of New South Wales, 1900. 



