SOIL ACIDITY 



245 



limestone contain particles of calcium carbonate which slowly 

 dissolve, yielding a solution which neutralizes any acids re- 

 sulting from organic decomposition or selective absorption. 

 Little calcium is as a rule present in silicate form and hence 



in \ 



.) .hut 



— S 



/uti.. - 

 <>' i ■ 



«K> ll»>(.»..««.r i <Ml 



Fig. 58. — Effect of sufficient limestone in the soil to neutralize the acidity 

 from ammonium sulphate. Corn. General fertilizer plats, Department of 

 Agronomy, Pennsylvania Station. 



little carbonate can be produced from this source. In time 

 all the calcium carbonate is dissolved out and then the acid 

 condition of the soil asserts itself. This solution of calcium 

 carbonate takes place rapidly and completely. 



