No. 4.] FIELD CROPS. 317 



kinds and amounts of other foods being given in connection 

 with these feeds in each instance, — nave in eight weeks 121 

 pounds less milk than the silage; and the cows receiving 

 silage gained slightly in weight, while those receiving man- 

 gels lost in weight. It will cost to produce 40 pounds of 

 mangels almost exactly twice as much as it will cost to pro- 

 duce the 30 pounds of silage. 



.Man, however, cannot live on corn stalks, and it may be 

 doubted whether he would thrive on either mangels or 

 Swedes, even should these be used in connection with some 

 meat and other more nitrogenous foods. He can live on 

 potatoes, with a little meat or fish. We may not, therefore, 

 justly compare the potato with corn for the silo as a food 

 producer. To utilize the calorics of energy put into the 

 silo, we must place a cow or a steer between the door of the 

 silo and our mouths. Here it is usually the cow, and she 

 should return us about 3,200 quarts of milk for the product 

 of one acre in corn. This milk will contain only a little 

 over 2,000,000 calories of energy, — just about one-fifth of 

 the amount we put into the silo. The potato gives us 

 rather over 6,000,000; so it appears that the potato as a 

 producer of human food stands far ahead of corn utilized 

 through the medium of the cow. Should we ourselves con- 

 sume the grain produced by an acre in corn, and feed the 

 stover to cows, the two would stand more nearly upon an 

 equality. On the basis of a yield of 7"> bushels of grain and 

 2% tons of stover, I figure, in grain, 7,057,620 calories, and in 

 the milk which could be produced by the stover a little over 

 1,000,000 calories, — a total of 8,071,(i20 calories of energy. 

 The corn on this basis stands ahead of the potato; but corn 

 is much less palatable than the potato as an every-day food, 

 and, moreover, requires expensive and laborious prepara- 

 tion, while the potato does not. A\ Y see, therefore, that 

 among the crops under consideration the potato stands at 

 the head as a human food producer; and I may add that 

 among all the crops that can be grown in temperate cli- 

 mates there is probably not one which can equal it in re- 

 spect to the amount of human food which can be produced 

 from a given area. It would undoubtedly be quite as difli- 



