346 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



earth. The salts of mag-nesia, potash and soda are peculiar to the sea. If 

 the proportions of sea and land were reversed, it is easy to see what the 

 effect would be upon vegetable existence. All plants require potash, which 

 may in many cases be replaced b}"- magnesia, soda or lime, these substances 

 can readily be placed in the irrigating" liquid and thus given to the plants, 

 which in turn 3'icld it to animals for the formation of their bones, and they 

 reject from their systems any exc(>ss that there may be in their liquid excre- 

 tions. If two vegetables are made to grow in the same field, each with- 

 drawing precisely the same food from the earth the}'' injure each other, so 

 corn and pumpkins planted as is customary together mutuall}^ injiu'c each 

 other. Though plants will grow well together when the substances requi- 

 site for their growth taken from the soil are of different kinds, or in fact 

 when they are not each in the same stage of growth at the same period of 

 time. If a soil is rich naturally in potash, tobacco and wheat may be grown 

 in succession, because the tobacco does not make use of the phosphates, 

 which the wheat does. Tobacco requires alkalies and nitrogenous food only. 



If we grow wheat in the same field for j^ears in succession, it annually 

 leaves behind an excrement, which decreases the yield of every succeeding 

 crop of wheat until it fails to produce at all; but if different plants are 

 grown in succession, the first leaves behind an excrement which helps the 

 second, and the second, that which may benefit the third, and the soil will be 

 admirable for the three kinds. If, for instance, jon sow wheat it will take a 

 large portion of the silicate of potash from the soil, therefore, it should be 

 followed by plants that make little use of potash, such as turnips and pota- 

 toes, and sow wheat again after four years have elapsed, and let the courses 

 be 



1st. Turnips, which will produce 26 tons of turnips and 8 tons of tops. 



2d. Oats, which will produce 60 bushels and a ton and a half of straw. 



3d. Clover and timothy, which will produce 2| tons of hay. 



4th. Wheat, which will produce 40 bushels and 2| tons of straw. 



If stock are not permitted to eat any of these crops upon the land the 

 inorganic matter contained in them would be 



Lbs. 



Soda 135 



Magnesia 50 



Potash 300 



Alumina 12 



Lime 310 



Silica 320 



Phosphoric acid TO 



Sulphuric acid 115 



Chlorine 40 



making a weight of 1,352 pounds carried off the land; to restore it then to 

 its original condition, we must add to every acre every four years 

 250 pounds of pearl ashes; 

 350 " carbonate of soda; 



TO " of common salt; 

 250 " of quick lime; 

 152 " of sulphate of ammonia; 



80 " of alum; 

 200 " of bone dustj 



