SOILS AND FERTILIZERS 531 



of legumes begins to give evidence that, all other conditions being 

 the same, it is not producing the highest yields. The cause may be 

 that the bacteria already in the soil are losing their virulence, and 

 the only way to be certain of this is to try inoculation and note 

 results. 



Since the only purpose in adding the bacteria to the soil is to 

 furnish nitrogen to the plants in an available form, usually with 

 root nodules, it is evident that where the organisms are already 

 abundant and the crop is thriving, but little benefit can be expected 

 from an additional inoculation. Neither is inoculation necessary 

 where the soil is already very rich in nitrogen, nor where it is al- 

 ready full of nitrogen-fixing bacteria. 



Inoculation Will Fail. (1) When the directions for prepar- 

 ing the solution are not carefully followed; (2) when the soil is 

 too acid or or too alkaline to permit the development of either plants 

 or bacteria; (3) when the soil is deficient in other necessary plant 

 foods, such as potash and phosphorus, as well as nitrogen. Above 

 all things, it should be remembered that no inoculation will over- 

 come poor results due to bad seed, improperly prepared seed beds, 

 bad cultivation of land, weeds and grass, or adverse climatic condi- 

 tions. Liming where needed and the addition of phosphatic and 

 potash fertilizers should not be neglected. (Y. B. 1902; Va. Ex. 

 Sta. B. 159.) 



BREEDING NITROGEN INTO FIELD CROPS. 



There are few general considerations in the breeding of plants 

 and animals which are more important than that of breeding a 

 stronger tendency toward the production of nitrogen compounds. 

 Protein is worth, 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 com- 

 pounds which help to elaborate plant food from the insoluble min- 

 eral and nitrogen compounds in the soil. 



On the other hand, the protein 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 per acre, as well as the 



