FERTILIZERS ON SANDY SOIL — SMITH. 125 



^would ill a short time become insolul jle double phosphates. Witli 

 manure the case is different. All our manure is applied l)efore 

 fermentation begins. It contains no ammonia, but presumably 

 ammonia is formed in the soil from the soluble nitrogen com- 

 pounds it contains. The conditions which would tend to cause 

 this change would be such as would favor nitrification, and the 

 ammonia w^ould immediately be converted into nitric acid. These 

 conditions are decaying organic matter in contact with the soil 

 containing nitrifying ferments. When ammonia salts as a ferti- 

 lizer are applied, such is not the case, and the salts, if applied in 

 any considerable quantities, would retard the action of the fer- 

 ments, or might even kill them. This is only a surmise till we 

 have investigated it more fully ; but whatever the cause, ammonia 

 salts, as will be shown, appear actually iujurious to most of our 

 crops, especiall}^ potatoes. This we suggest as an explanation 

 till we have found out what is the truth. Phosphates, wli ether 

 in manure or not, soon become precipitated into insoluble phos- 

 phates. These are dependent on what bases are most abundant 

 in the soil. In manure the phosphates are, like all the other 

 constituents, very finely divided, and the decomposition of pro- 

 ducts of the manure tend to hold the phosphates longer in solu- 

 tion or to dissolve those freshly precipitated. This would not be 

 the case with phosphates of fertilizers, for they have no organic 

 decaying matter in close proximity to them unless we except 

 fine gi'ound bone, and that class of fertilizers. The potassium is 

 present first as carbonate, then as rapidly as nitric acid forms it 

 would be combined with it and with the other organic acids 

 present. Its tendency would be to pass over into the zeolites in 

 a short time. 



PART II. 



Plants : — Their Composition and Relation to the Soil. 



The elements essential to agricultural plants are potas- 

 -sium, calcium, magnesium, phosphorus and sulphur. Besides 

 there are constantly found in plants, iron, chlorine, sodium 

 and silicon. Iron undoubtedly is indispensible to the growth 

 •of plants. Chlorine might possibly be added also. In regard 



