FORAGE CROPS. 361 



f Insoluble siliceous matter. . . .74*61 



{Consisting of — Alumina 4-27 



Lime (in a state of silicate) 4-07 



Magnesia '46 



I Potash -19 



I Soda 23 



(^ Silica 65-29 



9968 



''This soil, it will be seen, contained, in appreciable quantities, 

 not only potash and phosphoric acid, but all the elements of fer- 

 tility which enter into the composition of good arable land. It 

 may be briefly described as a stiff' clay-soil, containing a sufficiency 

 of lime, potash, and phosphoric acid to meet all the requirements 

 of the clover crop. Originally rather unproductive, it has been 

 much improved by deep culture ; by being smashed up into rough 

 clods early in autumn, and by being exposed in this state to the 

 crumbling effects of the air, it now yields good corn and forage 

 crops. 



" In separate portions of the three layers of soil, the proportions 

 of nitrogen and phosphoric acid contained in each layer of 6 inches 

 were determined and found to be as follows : — 



Soil dried at 212° Fahr. 

 1st 6 inches. 2d 6 inches. jd 6 inches. 



Percentage of phosphoric acid '^49 .... *I34 .... '172 



Nitrogen -162 .... '092 .... 064 



Equal to ammonia 



" In the upper 6 inches, as will be seen, the percentage of both 

 phosphoric acid and nitrogen was larger than in the two following 

 layers ; while the proportion of nitrogen in the 6 inches of surface 

 soil was much larger than in the next 6 inches ; and in the third 

 section, containing no visible particles of root-fibers, only very 

 little nitrogen occurred. 



" In their natural state the three layers of soil contained : — 



Moisture 



Phosphoric acid . . . 



Nitrogen 



Equal to ammonia. 



Weight cf I foot square of soil. . 



" Calculated per acre, the absolute weight of i acre of this 

 land, 6 inches deep, weighs : — 



