41 



fetching up to par some one or all of these four elements, 

 viz., nitrogen, potash, phosphorus in the form of phos- 

 phates, and lime. The best way toaonA'ince ourselves that 

 the orchard soil must have them, is to take the ash of our 

 common fruits and find out by analysis what mineral con- 

 stituents are found therein, and how much of each. Every 

 fraction of those constituents has been got out of the soil, 

 and the practical outcome of manuring consists in giving 

 them back again in such form that the plant can readily 

 take them up. This table will make the matter clear. 



The above are percentage amounts. Those of* soda and 

 silica are omitted, seeing that these substances, although 

 present, are not plant-food ; nor does the table con! am 

 estimates of nitrogen or carbohydrates, for these sub- 

 stances are burnt oft in the production of the ash. The 

 woody substance of the trees themselves contains exactly 

 the same elements. That of the apple-tree for example 

 contains 



Potash. 

 19-24 



Lime. 

 63-60 



Magnesia. 

 7-46 



Iron. 

 07 



Phosphorus. Sulphur. 

 4-90 3-29 



No one can examine the abov r e percentages without clearly 

 understanding what mineral substances go to make his soil 

 fertile, and therefore what he has to give back to it in 

 order to keep it so. 



46. Let us take these fertilizers in their order. Nitro- 

 gen. Trees take up what nitrogen they need as nitrates or 

 as ammonia. In soils such as would be selected for orchard- 

 ing, especially if prepared as directed in the preliminary 



