FARM LANDS OF NEW SOUTH WALES. 



INJURIOUS SUBSTANCES IN THE SOIL.* 



Bare Patches. 



It frequently happens that large or small areas of land are found to be 

 unproductive or of poor quality, although from their origin, and the nature 

 of the surrounding country, one would expect them to possess a high 

 degree of fertility. Of such nature are the bare patches often met with in 

 otherwise fertile areas. 



Such bare patches may occur in areas of a few feet in diameter, or may 

 be of very considerable extent. The causes of this infertility are various, 

 and it is by no means easy in all cases to determine to what their unpro- 

 ductiveness is due. 



The following are some of the instances most commonly met with : — 



Shallowness of Surface Soil. 



It may happen that the rock from which the soil is derived has weathered 

 unequally in different parts, and that undecomposed rock is found quite 

 close to the surface, thus forming a very shallow surface soil on which 

 nothing but the most shallow-roofed crops will grow, and resting on a hard 

 stratum through which water will not penetrate. Crops or trees growing 

 on such soil may do fairly well until the roots reach the impervious layer, 

 when they begin to wilt. 



The same result is produced when a hardpan or layer of impervious 

 material is formed below the surface. This hardpan may be formed mechani- 

 cally by the plough, either by ploughing stiff clay when it is wet, or by 

 ploughing repeatedly at the same depth. It may also be formed naturally 

 by the cementing together of the particles of sand and gravel of the subsoil 

 by humates and silicates, particularly humates and silicates of iron and 

 lime, and is especially likely to occur in ironstone country. The remedy is 

 to break up the hard layer by deeper ploughing, and to apply slaked lime. 



Scalded Plains. 



Where conditions are such that a shallow and dry surface soil, or a soil 

 deficient in vegetable matter, is exposed to the action of wind, large areas 

 are frequently denuded. In such cases the top soil is carried away and a 

 hard surface exposed, destitute of vegetable matter, and which is useless for 

 the production of crops, or even of grass, until it has been thoroughly worked 

 and brought under cultivation for some time. These patches form the well- 

 known scalded or scoured plains of greater or less extent occurring: in the 

 arid and semi-arid districts, and particularly in thinly-timbered country. 



The same thing happens in such parts as have been heavily trampled by 

 stock on stock routes and camping-places. Such lands require only to be 

 well ploughed and exposed to the influence of rain and sun to render them 

 again productive. 



* F. B. Guthrie. 



