TABLE OF CONTENTS. 



Page. 



On the derivation and the formation of soil 



Composition of the soil 



General classification of soils 



Geological classification of soils 8 



Difference between the soil and the subsoil 8 



Weathering of the rocks and formation of the soil 8 



The soils formed by the different geological formations 9 



The denudation of the soil 



The quantity of soil swept away by the rain replaced by the decomposition of 



the rocks 10 



The general fertility of the soils depends principally on their texture 10 



The physical properties of soils 10 



Importance of a proper mechanical condition 11 



Variations in the texture of soils influence their fertility 11 



The absorbent and retentive powers of soils 11 



Absorption of ammouiacal salts by various soils 



General conclusions in regard to these powers 



The power of retaining moisture in the soil 13 



The temperature of the soil 14 



Fertility of the soil depends on climatic conditions 14 



The barrenness of soil 14 



The average composition of ordinary farm crops 



Permanent fertility 16 



Acquired or temporary fertility 



Improvement of the soil 17 



The mechanical analysis ot soil 17 



Objection to the mechanical analysis of a soil 18 



Principle applied to most of the apparatus used for this purpose 18 



Schloesing's method for the mechanical determination of clay 19 



The effect of various proportions of sand in the soil 19 



The chemical properties of soil 19 



Great care necessary in obtaining the sample for analysis 20 



The chemical composition of soils 20 



The organic matter 20 



The inorganic or mineral portion of the soil 21 



Silica 21 



Alumina, clay 21 



Lime 



Ferric oxide 23 



Phosphoric acid 



Potash 24 



Soda 24 



Magnesia - 24 



Sulphuric acid and chlorine 24 



Nitrogen and nitrates 24 



Fertility depends on the minimum quantity of any necessary constituent; pres- 

 ent.. 28 



5 



