PRINCIPLES OF FERTILITY. 



135 



the little hair rootlets which are everywhere attached to the roots of 

 the plant, running ont into the soil. If you take any plant and 

 careftiUv wash the earth awav from the roots, instead of tearing 

 it away, you will find that they are covered in every direction 

 with minute hairs ; and it is through those hairs that the nourish- 

 ment, so to speak, is taken up by the plant. You at once see the 

 philosophy of having your material in a liquid form. There is a 

 supply of every one of these elementary materials in all of our agri- 

 cultural soils, even in our run out soils, suflicient to give payino- 

 crops for an indefinite [)eiiotl of years ; but they are in a ft^rm that 

 is not soluble in water, and the plants cannot avail themselves of 

 them, and hence do not grow. 



There are methods by which we can aid in rendering these ma- 

 terials that now exist in the soil soluble, so that the plants mav 

 a|)propriate them. Atmospheric infiuences acting upon them tend 

 to nuike them soluble. We stir up the soil by plowing, upturn- 

 ing material which before lay out of reach, in a measure, of the 

 influences which tend to render the material soluble. We expose 

 these particles of soil containing this plant food to these atmos- 

 pheric influences — to the action of the sunshine, the rain, the frost — 

 thereby rendering a portion of the plant food soluble. We continue 

 a limited amount of crop production by that method alone, and 

 certainly aid in getting a profitable croi). But that operation is not 

 rapid enough, or sufficient for our wants ; so we are called upon, as 

 intelligent farmers, to add to the store in the soil, in order to give 

 the additional amounts which are needed to return to us the bounti- 

 ful crops which we find are necessary to a profitable cultivation. 



Manuring the soil, then, resolves itself down to this simple propo- 

 sition : supplying nitrogen, phosphoric acid and potash, one or the 

 other, or all three, to the soil ; this, and nothing more. The value, 

 then, of a manuie, you will see at once, is determined by the amount 

 of nitrogen, phosphoric acid and jwtash there is in it. The barn 

 manures we recognize as our standard. Those manures are valu- 

 able for the number of pounds of nitrogen, phosplioric acid and 

 potash there is in them. We go into the market and bu}- a commer- 

 cial fertilizer. That commercial fertilizer is valuable for just the 

 luimber of pounds of nitrogen, phosi)horic acid and potash there is 

 in it. and for nothing further. So you see tiie commeicial fertilizers 

 marked (and the law requires it) three or four per cent, nitrogen, 

 ten per cent, soluble phosphoric acid, three or four per cent, potash. 



