144 Fertilizers 



abundance rendered the phosphoric acid less efficient as 

 a plant-food, but experiments have shown this theory to 

 be greatly overdrawn. 



Less plant-food required. 



Careful study of the foregoing paragraphs shows clearly 

 that less plant-food is required where lime is used in liberal 

 quantity. In general, less nitrogen, phosphoric acid and 

 potash need be added to soils well supplied with lime and 

 in good tilth for satisfactory crop production than in the 

 case of soils deficient in lime. 



Injurious chemical effects. 



Lime hastens the decomposition of organic matter and 

 the formation of nitrates, as previously stated. If condi- 

 tions are unfavorable to the formation of nitrates, the 

 decomposition of organic matter may be accompanied by 

 a loss of nitrogen which escapes into the air as a gas. In 

 case all conditions are favorable for nitrification, nitrate 

 nitrogen may be formed in the soil more rapidly than the 

 plant-life present is capable of utilizing it and much of it 

 would be leached from the soil and lost in the drainage 

 water. This is more likely to occur in connection with 

 the use of burned or hydrated lime, especially on light 

 soils, than with the use of ground limestone. 



Effects of gypsum. 



Gypsum, land plaster or calcium sulfate previously 

 mentioned should not be confused with lime, though it is 

 similar in the respect that it carries the element calcium. 

 Unlike lime, gypsum will not correct acidity, and its con- 

 tinued use actually makes soils more acid, but it has the 

 advantage of changing ammonium carbonate which is 



