248 BOARD OF AGRICULTURE. 



arc large, and in the case of wheat grain come next to lime, 

 forming one-eighth of the whole amount of ash. 



In countries where magnesian limestone abounds, the supply- 

 may be fully afforded by the soil. In France, Germany and 

 England this is probably the case ; but in New England we can- 

 not form a perfect manure and overlook the magnesian salts. 

 In all the treatises and statements respecting fertilizing agents 

 made by our chemists and experimenters, we find scarcely any 

 allusions to the importance of the magnesian element, and this 

 is indeed a matter of surprise. 



It probably arises from the practice of copying the results of 

 European writers — not from the deductions of original and inde- 

 pendent research. Our soils are not constituted like those of 

 Europe, and in the application of fertilizing principles they 

 require different treatment. A perfect manure, then, adapted 

 to our soils, should contain nitrogen, phosphoric acid, lime, 

 potassa and magnesia. 



For the cereals, excess of nitrogen is demanded ; for legu- 

 minous plants, as pease, beans, &c, potassa ; for roots or tubers, 

 phosphates. All demand lime and magnesia, and these must be 

 supplied in the perfect food made ready for the plant- children of 

 our fields. 



Three questions remain to be answered : First, how shall we 

 properly prepare these elements of nutrition ? Second, how 

 shall we apply them ? Third, where can we obtain them ? 

 Chemistry is fully capable of answering the first. Apply all 

 substances to the soil in the finest state of comminution ; bring 

 everything into a condition resembling as nearly as possible the 

 excrementitious products of animals, which is the true condi- 

 tion. The bone for phosphoric acid must be reduced to an 

 impalpable powder, and this is not .its best form ; it is better to 

 dissolve it in acids or caustic alkalies, whose teeth are sharper 

 than burr-mills or any mechanical levigators. 



The potash must be in combination with carbonic acid, or in 

 the form of carbonate of potassa. This is the most easily 

 assimilable form, but in the caustic condition, as in ashes, it is 

 readily changed to carbonate by contact with air. 



The nitrogen must be furnished through ammonical com- 

 pounds, or nitric acid salts. Lime in form of phosphate, hydrate 

 or carbonate, may be employed, and the sulphate of magnesia 



