CROPS AND SOIL IMPROVEMENT 



pounds of nitrogen, 5 pounds of phosphoric 

 acid, and 10 pounds of potash. This makes the 

 percentage of nitrogen and potash the same, 

 while the percentage of phosphoric acid is only 

 half as high. A commercial fertilizer of such 

 percentages would be esteemed a badly balanced 

 one. Certainly the phosphoric acid should be 

 relatively high, as this constituent of plant- 

 food runs low in the soil. If 50 pounds of 14 

 per cent acid phosphate were added to each ton 

 of manure while it is being made in the stable, 

 7 pounds of phosphoric acid would be added, 

 making the percentage in the manure a little 

 higher than that of the nitrogen and the potash. 

 A better balance is given to the fertility. There 

 cannot be any loss in this purchased plant-food, 

 if the stable floor is tight. Fermentation cannot 

 drive it off, and when applied to the soil it is 

 tightly held. Practically no phosphoric acid is 

 found in drainage waters. Eight tons of manure 

 thus reenforced would contain the same amount 

 of plant-food as a ton of fertilizer having 4 per 

 cent nitrogen, 5 per cent phosphoric acid, and 

 4 per cent potash. The addition of the 50 

 pounds of acid phosphate per ton does not bring 

 the phosphoric -acid content up as high relatively 



[146] 



