HOW LEGUMES HELP THE FARMER 



45 



obtained from the Department of Agriculture, Washington, 

 D. C. The directions for using accompany each bottle. 



Acid Soils. Nitrogen-gathering bacteria do not grow 

 well in acid, or "sour," soils. Soil acidity, when very 

 marked, may be determined by means of blue litmus paper. 



FIG. 19. Roots of soy bean, showing nodules. (From Farmers' Bulletin No. 214.) 



This can be bought at a drug store. The soil is tested by 

 moistening a sample of it with water and placing a piece of 

 blue litmus paper in it for a few minutes. If the soil is 

 strongly acid, it will turn the litmus paper from blue to 

 red. To correct acidity in soil, ground limestone should be 

 applied at the rate of one to two tons to the acre. Some 



