42 PLANT BREEDING. 



increasing its content of nitrogen compounds, collectively called 

 protein. 



BREEDINO NITROOEN INTO FIELD CKOl'S. 



There are few general considerations in the breeding of i^lants and 

 animals which are more important than that of breeding a stronger 

 tendency toward the production of nitrogen comj^ounds. Protein is 

 Avorth, on the average, about 4 cents per pound in those substances 

 used for food for animals and man, while carbohydrates and fats, 

 excepting in special forms, as in highly flavored butter, are worth 

 much less. The farmer can produce starch, cellulose, and sugar 

 in his staple field crops for a small fraction of 1 cent per pound, 

 often a very small fraction. The carbonaceous substances contain 

 neither nitrogen nor mineral fertilizing substances, and their use as 

 plant food is limited to improving the water-holding power of the soil, 

 and, upon decaying, furnishing active compounds which help to elabo- 

 rate plant food from the insoluble mineral and nitrogen compounds 

 in the soil. 



On the other hand, the jjrotein of our food plants, in addition to 

 being very valuable as a food, is a most important fertilizer. In 

 addition to its value of about 4 cents per pound as a food stuff, pro- 

 tein compounds are worth, at the commercial rate of nitrogen, about 

 2 cents per pound as fertilizers. Assuming that half of the nitrogen 

 can be retained for fertilizer on the farm upon which the crops of 

 grain and forage are grown and fed to animals, we have 1 cent per 

 pound valuation of the protein in the foods we raise for our animals 

 as a manure to add to its value of 4 cents per pound as a food for 

 live stock. These values can not all be secured and realized by the 

 farmer, because he sells some of his crops in the cities. We should 

 seek to increase the yield of nitrogen pev acre, as well as the total 

 yield of crop, just as the breeders of sugar beets must increase the 

 yield of beet sugar per acre rather than the tonnage of the roots, and 

 the breeders of dairy cows increase the 3'ield of butter rather than 

 the yield of milk. Thus we should add to the protein content of our 

 cereal and forage croi)s. In case of corn fodder there is a special 

 reason for increasing the content of protein. The varieties of corn 

 used for dry fodder or for silage already yield so well that a super- 

 abundance of roughage can easil}^ be produced. But to make it val- 

 uable as a balanced ration we must add to it expensive concentrated 

 foods, such as bi-an, oil cake, or other grain products. 



By increasing the i^ercentage of x)rotein in the fodder or silage a 

 less amount of the expensive grain foods will be required, and, the 

 ration being cheaper, will leave a larger margin of profit. But of even 

 greater importance is the breeding up of the nitrogen content in 

 clover, cowpeas, alfalfa, and other plants which gather nitrogen from 

 the air. These crops should not onlj'^ have their nitrogen content 

 increased, but they should also be so bred as to succeed far better 



