62 



THE FARMERS HANDBOOK. 



Classification of Soils. 



The classification which will be adopted in the following pages is that based 

 upon the mechanical condition of the soils and depending upon the propor- 

 tion of particles of different size. For all practical purposes one based on 

 the proportion of sand and clay is sufficiently close, and the following table 

 gives the standard which is adopted : — 



Nature of Soil. 



Clay. 



Gravelly soils contain over 20 per cent, gravel. 

 Calcareous soils „ „ 5 per cent. lime. 



Peaty soils „ „ 20 per cent, humus. 



There are, however, other methods of classification which can be usefully 

 adopted under different circumstances. For instance, the farmer will dis- 

 tinguish between light and heavy soils, plain, timber, and swamp soils, or 

 according to the nature of the vegetation, as pine country, box country, &c, 

 or according to the different crops for which they are particularly suitable, 

 as wheat land, lucerne land, grass land, &c. Another method of classification 

 frequently adopted is one depending upon their manner of formation into 

 sedentary and transported soils, and as these terms are commonly met with 

 in text-books, it will be useful to define them a little more accurately. 



Sedentary soils are those which overlie the rocks from which they are 

 formed, and transported soils are those which have been carried away by the 

 action of wind or rain, or streams, or by glacial action, from their original 

 positions. 



Transported soils are divided into colluvial soils, such as are found on 

 hillsides or in undulating country, which have been moved from their 

 original position by the agency of wind or rain, and alluvial soils which 

 have been carried away by streams and rivers and deposited often far from 

 their original position by the action of running water. 



Sedentary soils are usually met with on upland plateaux and are generally 

 shallow, their depth depending upon the length of time during which denud- 

 ation has taken place and the amount of transportation which they have 

 undergone. They merge gradually and imperceptibly into the rock from 

 which they are derived, and a knowledge of the nature of the underlying 

 rock is of value in determining the character of the soil. 



Colluvial soils — Drift soils. — In the case of these soils the surface has 

 been removed from its original position, and has become mixed with soils 

 derived from other rocks, often of quite different character. 



Their transportation may have been brought about by a variety of causes, 

 such as the action in remote times of glaciers, or by the action of rain or of 

 wind or running water. 



Examples of drift soils blown about by the action of the wind are to be 

 found in the western plains, where the movements of the soil during con- 

 tinued wind-storms have resulted in the transportation of the surface soils to 

 new positions, where they are often piled up to the depth of several feet. 



