NDRTH-CAROLINA GEOLOGICAL SURVEY. 65- 



In the straw, per acre, the proportion of elements is : 



Phosphoric acid, 1.50 



Sulphuric acid, 2.50 



Chlorine, 3.00 



Lime, 5.00 



Magnesia, 15.00 



Potash and soda, 17.00 



Silica 24.00 



Oxide of iron, 1.00 



38. The clover plant weighs, when dry, 3693 Ibs. per acre. 

 The percentage of ash is 7.70, which is quite large, and the 

 weight of the ash, per acre, 284 Ibs. It contains, of 



Phosphoric acid, 18.00 



Sulphuric acid, 7.00 



Chlorine, 7.00 



Lime, 70.00 



Magneisa, 18.00 



Potash and soda, 77.00 



Silica, 15.00 



Oxide of iron, 0.90 



The clover plant, it will be perceived, contains about equal 

 proportions of lime, potash and soda ; the lime, however, is 

 in excess, but its composition shows why it is so well adapted 

 as a fertilizer to the wheat crop. The vigorous growth of 

 clover upon a soil which has been marled with green sand, 

 which contains both lime and potash, illustrates and places in 

 a strong light the advantages of special fertilizers. 



If the ash of the foregoing, or any other plant is compared 

 with the composition of the best soils, or marls, it will not 

 fail to strike almost any one that there is a dose resemblance 

 between them. The soil furnishes phosphoric acid, iron, sul 

 phuric acid, chlorine, magnesia, silica, potash and soda. All 

 the remarkable fertilizers contain the same elements. Those 

 which are the most striking in their effects contain lime, phos 

 phoric acid, potash and soda in large proportions, furnishing 

 thereby the expensive elements, the most essential ones, or 

 those which exist in the soil in the smallest proportions, in. 

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