BUYING PLANT FOOD FOR THE SOIL 22Q 



other hand, potassium has a tendency to prolong the 

 growth of crops, but its chief office is increasing the 

 yield or quantity of fruit. Consequently, when the yield 

 is small, you may conclude there is a deficiency of either 

 phosphorus or potassium or both in the soil. 



And again : if you observe that your plants are of rich, 

 green color and of good size, you may be sure they are 

 not in need of nitrogen. If, however, they are small and 

 pale and sickly in appearance, you may know that nitro- 

 gen is sorely in need. 



Nitrogen is the most costly element of plant food we 

 buy, and for this reason we should depend upon home- 

 made manures and the various legumes for every bit of 

 nitrogen that is needed on the farm. Of course, we can- 

 not get our phosphorus and potassium in that way. These 

 come from the soil and not from the air; hence, a de- 

 ficiency in either must come through some artificial 

 means. 



Sources of nitrogen. While nitrogen is one of the most 

 abundant of substances, just the same, it is one of the 

 easiest lost and used up in the soil. In buying nitrogen 

 as a fertilizer, you must seek a material already having 

 it in combination. In combination with the element 

 hydrogen (which is a constituent of water) ammonia is 

 formed, and a gas it is, also; and it is very soluble in 

 water. The pungent odor of ammonia water is due to 

 ammonia gas. Thus we get the same odor in stables and 

 fresh manure piles: ammonia gas is passing off into the 

 air, later to be brought down by dew or rain, fertilizing, 

 perhaps, some distant field. 



Ammonia has a great fondness for sulphuric acid, and 

 unites with it with vigor, giving rise to a substance white 

 and solid, and known to fertilizer dealers and users as 

 sulphate of ammonia. 



