24 Food for Plants. 



Anything above these figures would be called very 

 rich. Very poor soil would average about .08 per cent, 

 of Nitrogen and .08 per cent of potash and .08 per cent, 

 of phosphoric acid with humus of .30 per cent. Anything 

 less than these figures would be very poor indeed. 



The pounds of available fertility are reckoned to be 

 contained within eight (8) inches of the surface. The 

 weight of an acre generally w^ould run about two thou- 

 sand (2,000) tons. 



HOW MONEY CEOPS FEED. 



The substance of plants is largely 

 What the water and variations of woody fiber, yet 



Food Is. these comprise no part of what is com- 



monly understood as plant food. More 

 or less by accident was discovered the value of farm- 

 yard manures and general farm refuse and roughage as 

 a means of increasing the growth of plants. In the course 

 of time, the supply of these manures failed to equal the 

 need, and it became necessary to search for other means 

 of feeding plants. The steps in the search were many, 

 covering years of careful investigation, and as a result, 

 we have the established fact that the food of plants con- 

 sists of three different substances. Nitrogen, Potash, and 

 Phosphates. 



These words are now popular names. 

 Its Principal and are used for the convenience of the 



Elements, general public. Nitrate of Soda contains 



Nitrate, an amount equivalent to al)out 15 per 



Phosphoric cent, of Nitrogen, 300 pounds to the ton. 



Acid, Potash. and cotton-seed meal, for example, about 



6 per cent. More than three pounds of 

 cotton-seed meal are necessary to furnish as much avail- 

 al)le Nitrogen as one pound of Nitrate of 8oda. AVe 

 value the plant food on the amount of Nitrate Nitrogen 

 it contains, and on tliis account Nitrate has become a 

 standard name for this element of plant food. In like 

 manner, phosphoric acid and potash are standards,hence 



