EXERCISES WITH SOILS 



115 



baking effects of hot winds and sun. Heavy rains do not 

 pack them together so badly as heavy clay soils. Gardens are 

 much improved by plowing under green manure grown for this 

 purpose. 



5. Testing for Sourness. — A few cents' worth of litmus paper 

 may be purchased at a drug store. It usually comes in two colors, 

 pink and blue. A sample of soil freshly taken is tested by placing 

 a piece of the paper of each color in it. Cover the paper with some 

 soil and press it until the moisture affects the paper. Be careful 

 to avoid touching the paper with the fingers except at one end. If 

 either of the slips changes color, the character of the soil is deter- 



FiG. 64. — Garden soils should not be allowed to bake and crack either before or 



after planting. 



mined. A change from blue to pink indicates sourness or the presence 

 of acid in the soil. A change from pink to blue indicates that the 

 soil has lime or other alkali present. If there be no change in color 

 of either piece, the soil is " neutral," or nearly so. 



For most crops, soils should not be acid in their action 

 on litmus paper. If they be either neutral or show the pres- 

 ence of lime, they are suitable in this respect for most farm 

 crops. The acidity of any soil may be corrected by the addition 

 of lime. 



6. Taking Soil Temperatures. — ^A twenty-five-cent dairy ther- 

 mometer may be purchased at a drug store or from a dairy supply 

 house. Iti should be made of glass without a frame around it. This 



