404 AGRICULTURE OF MAINE. 



There are, on the other hand, the highly complex nitrogenous 

 compounds which contain nitrogen, phosphoric acid, potash and 

 other constituents. Therefore, whenever materials containing 

 these highly nitrogenous compounds which are usually grouped 

 under the general name of protein are removed from the land 

 and sold off, valuable fertilizing constituents which are essential 

 to plant growth are taken away from the farm. Obviously, if 

 there were only grown upon and removed from the farm by 

 sale or otherwise, those materials which consist of carbon, 

 hydrogen and oxygen without nitrogen or mineral constituents, 

 theoretically the agriculture w^ould be self-sustaining and the 

 farm could be maintained indefinitely without the addition of 

 any fertilizing materials. As, however, these non-nitrogenous 

 constituents will not of themselves build up animal life it is 

 necessary in the feeding of animals, human and others, to pro- 

 vide these nitrogenous and mineral constituents in the food. 

 While the farms of the land must supply all of the nitrogenous 

 and other food constituents rich in plant food which are essen- 

 tial to sustaining the life of those not living upon the farm, it 

 becomes the problem of the individual farmer not only to pro- 

 duce crops that will meet the public demand at the best possible 

 prices, but at the same time to sell from the farm the least 

 possible of the more valuable fertilizing constituents. Every 

 pound of nitrogen, phosphoric acid, potash and other mineral 

 constituents removed from the land must be replaced or else 

 there will be a diminishing fertility to the soil. 



That crops differ widely in the amount of plant food they 

 contain is illustrated by the following : 



A ton of apples (about 45 bushels) carries less than three 

 pounds of nitrogen, practically no phosphoric acid and four 

 pounds of potash, the fertilizing value of which is about 70 

 cents. 



A ton of strawberries (a little over 1000 quarts) carries three 

 pounds of nitrogen, two pounds of phosphoric acid and six 

 pounds of potash, the fertilizing value of which is about $1.10. 



A ton of potatoes (33 bushels) carries a little more than four 

 pounds of nitrogen, one and one-half pounds of phosphoric 

 acid and ten pounds of potash, with a fertilizing value of about 

 $1.30. 



