663 



expect from the indications given by the varieties of trees that 

 grow on the land. 



Soils are divided into two parts, the surface soil, which is the 

 most tortile, and composed of the liner parts of the s il, and the 

 subsoil, which may be composed of similar substances to the surface, 

 or it may be a coarse gravelly sand or even a stiff clay. . 



Soils are mainly composed of four constituents, clay, sand, lime 

 and organic matter, and generally derive their name from which- 

 ever of these constituents predominates. There is a good deal of 

 vagueness in the terms applied to soils by different persons. They 

 are variously called heavy, light, stiff, cold, damp, sandy, clayey, 

 peaty, calcareous, or loamy, none of these terms meaning anything 

 definite. Professor Johnstone gives the following classifications : 

 Soil, not peaty, that contains no more than 10 per cent, of clay is 

 called a sandy soil ; 10 to 40 per cent., a sandy loam ; 40 to 70 per 

 cent., a loamy soil ; 70 to 85 percent., a clay loam ; and 85 to 95 per 

 cent., a strong clay. 



The fertility of a soil depends mostly on its chemical, physical 

 and biological properties. 



ABSORBTION OF WATER. 



This is a very important property of the soil. Much depends, 

 for its fertility, on its power to absorb moisture, to take in 

 and retain water that may fall on it in the form of rain. This 

 depends greatly on the constitution of the soil, and also on the 

 fineness of its particles. Sandy soils possess this power in the 

 lowest degree, then clay, limestone, and humus in their order. 

 Schiibler gives the following powers of different soils to absorb 

 water : 



PER CENT. OF WATER ABSORBED BY 100 PARTS OF EARTH. 



Silicious sand ... ... 25 



Calcareous sand ... ... 29 



Gypsum 27 



Sandy clay ... ... ... 40 



Strong clay 50 j Arable soil 52 



Fine calcareous earth ... 85 Garden earth ... ... 89 



Humus ... ... ... 190 



It is necessary that the soil should hold sufficient \vater for the 

 nourishment of the plants, as they require water in order to 

 assimilate their food. 



The capillary action of a soil depends greatly on the fineness 

 of the particles. The finer the particles, up to a certain degree, the 

 more water is the soil enabled to draw from the deep sub-soil for 

 the benefit of the plants, hence the necessity of a good tilth. 



THE RETENTIVE POWER OF SOILS. 



This power is very much allied to that of the power of 

 absorbtion. As the rain falls only at intervals in some places, as in 

 this colony, the periods between the showers of rain being often of 



