56 FARM AND SCHOOL PROBLEMS. 



All essential elements to soil fertility must be present to in- 

 sure a profitable use of lime. 



Land should be tested occasionally to determine if there is 

 need of lime. 



Facts About Bacteria and Nitrogen. 



1. The increase of the number of organisms or bacteria, continues 

 almost proportionately to the application of lime in amount up 

 to three tons per acre. 



2. The nitrogen-fixing powers of soils or the amount of nitrogen 

 fixation is almost directly proportionate to the increase in the 

 number of nitrogen fixing bacteria, both increasing in the pro- 

 portion to this application of lime up to three tons per acre. 



Relation of Lime to the Supply of Nitrogen in the Soil. 



1. The supply of available nitrogen in the soil for the use of plants, 

 depends upon the fixation of atmospheric nitrogen. 



2. Certain kinds of bacteria take nitrogen from the air. 



3. The continued growth of certain plants called legumes depend 

 upon the chemical changes brought about by the bacteria that 

 form nodules on the roots of alfalfa, clover, beans, vetches and 

 soy-beans. 



4. Nitrogen fixing bacteria do not thrive in acid soils, which ac- 

 counts for the fact that legumes do not grow in soils contain- 

 ing acids. 



5. Research Bulletin No. 2, Experiment Station at Ames, Iowa, 

 shows that the application of lime is a determining factor 

 in the increase of bacteria. 



The experiments showed the following results: 



1. Applications of ground limestone increase the number of bacteria 

 in the soil. 



2. The increase of bacteria continued almost proportional to the 

 size of the application of lime up to three tons per acre. 



3. A test of ground limestone in earthenware pots each containing 

 30 pounds of soil, showed that a half ton application of the 

 limestone per acre caused an increase of 534,000 bacteria per 

 gram of earth. 



4. An application of one ton per acre caused an increase of 

 939,000; an application of 2 tons caused an increase of 1,649,000, 

 and an application of 3 tons resulted in an increase of 2,710,000 

 per gram of earth. 



