MINERAL MANURES. 



CHAPTER XXXII. ,. 

 MINERAL MANURES. 



Although the mineral parts of plants the ash form a 

 very small proportion of their substance, yet they are indis- 

 pensable to their growth. Without silica, the corn or wheat 

 plant could not stand erect, but would lie upon the ground; 

 without lime and phosphoric acid, there could be no seed, 

 and vegetable substance could not support any animal. The 

 mineral elements of plant substance, in fact, form the skel- 

 eton or frame so to speak, upon which the organic matter 

 is built; just as the bones of an animal support the fibrous 

 and vascular tissue which make up the apparent structure* 

 Some plants indeed are so well supplied with mineral matter 

 that their remains after the organic matter has decayed and 

 has been dissolved away, make the most delicate and beau- 

 tiful tissue, which remains intact after thousands of years dur- 

 ing which vast masses of these skeletons or shells have been 

 consolidated into clay or stone. Being thus indispensable 

 to the growth of plant substance, the mineral elements of 

 plant food bear a most important relation to the culture of 

 farm crops, and furnish a subject of study to the farmer 

 which he cannot ignore. 



Knowing what mineral substances are contained in plants, 

 and knowing that these are all derived from the soil; also 

 knowing that while the soil contains a large amount of all 

 these mineral substances, they are not in an available con- 

 dition for the food of plants, it is not difficult to arrive at a 

 conclusion in regard to what must be supplied to the soil to 

 ensure a satisfactory growth of crops. 



Moreover, it has been learned by long experience and 

 careful experiment that certain alkaline substances exert a 

 remarkable effect upon organic substances in the soil, when 

 they are brought into contact with each other; and further 

 that they have a very intimate relation with various changes 



