HOW TO MAINTAIN FERTILITY 



necessary to discuss here. Gypsum is just as good 

 as lime for all these reasons excepting the correc- 

 tion of soil acidity. 



To determine if the soil is sour, one of two 

 methods can be used. 



Take a fair sample of the soil and mix enough 

 water with it to make the mass the consistency of 

 thin mortar, then embed in it a strip of blue litmus 

 paper. Allow it to stand half an hour or more, and 

 then, if the paper has turned pink, you will know 

 that the soil is in need of lime. 



Another way is to place a tablespoonful of soil 

 in a glassful of water and a teaspoonful of weak 

 ammonia. If, after standing several hours, the 

 liquid becomes dark-brown or black, it is an indi- 

 cation of soil acidity. 



The amount of lime necessary will vary accord- 

 ing to the soil. Light, sandy loams will not need 

 more than 500 pounds per acre, twenty-five pounds 

 for a plot 25 X 100 feet, but when applied to 

 heavy clay loams, as much as 5,000 or 6,000 

 pounds can be used, 250 to 300 pounds on a 

 25 X 100-foot plot. These applications of lime do 

 not need to be made oftener than once in five to 



seven years, 



[45] 



