PART II. THE SOIL 



SECTION I. SOILS AND THEIR PROPERTIES 



THE soil has two important and entirely distinct functions 

 for assisting the growth of plants, (a) To supply a support 

 and room for growth, and (b) to act as a storehouse for 

 plant foods. The first of these functions is almost entirely 

 of a physical character, the second is both physical and 

 chemical, and very largely on the border-line between those 

 two sciences. 



Inspection of Soils. Some general observations can 

 be made on the spot by examining the soil in the field. 

 Whilst the analysis of soils is a complicated business, which 

 is not treated in this book, but left to the text-books specially 

 devoted to such a very highly technical subject, yet the 

 preparation of a soil sample which is required for analysis 

 is a very important subject, and can very rarely be carried 

 out by the actual analyst. For examining the suitability 

 of a soil for specific crops and fertilizers, a very good plan is 

 to dig a few holes in the field and inspect the soil. Once 

 a hole has been dug in the ground it is easy to obtain a smooth 

 vertically cut surface, which can be observed without 

 disturbing the soil. It will generally be observed that at 

 some depth the nature of the soil changes, often fairly 

 abruptly. This change is brought about partly by the action 

 of ploughs opening the soil to a particular depth, or by the 

 natural limitations imposed upon the vegetation of the 

 surface. 



When a hole has been dug in a field, and a good vertical 

 surface been obtained, it must then be decided how the slice 

 is to be cut, and divided as regards depth. Where time 



