OP AGRICULTURE. 37 



proportion of any ordinary soil. A single crop 

 takes away but little of any one ingredient, but still 

 repeated cultivation of similar crops for many years 

 must greatly diminish the supply of those mineral 

 elements found in the ashes of plants. Every bushel 

 of wheat, every bushel of corn, every bushel of 

 rye, &c., takes away phosphate of lime from the soil, 

 as also every bushel of cotton seed, if the seed is not 

 returned to the land as a manure for corn or cotton. 

 Then again, every fatted ox carries with him a good 

 many pounds of the phosphate of lime, to market, 

 which came from the soil upon which his food was 

 produced. Hence, this constant depletion must be 

 met by the application of bone dust, or phosphate 

 of lime. 



The general experience of the world is that all 

 lands become exhausted by long continued tillage without 

 manure. The mineral elements become exhausted by 

 by improper cultivation. The vegetable matter or 

 mould in the soil is decomposed, and gradually disap- 

 pears. Unless fresh portions are supplied a deficiency 

 must result. Ammonia is still more rapidly exhausted. 

 The material supply of ammonia in the soil is not 

 abundant, while its volatility and chemical activity 

 causes it to be constantly escaping, or undergoing 

 changes of form and combination. Henue the 

 necessity of artificial fertilizers. 



From what has been said of the physical and 

 chemical condition of soils, we may safely infer 

 they need fertilizers. A fertilizer is any substance 

 which, when applied to a soil, will preserve or increase 

 its productiveness. 



Whenever, then, we would enrich a barren waste, 



