CHAPTER XXXIV 



ANALYZING AND TESTING SOILS 



WHILE the chemical analysis of soils requires knowledge, train- 

 ing, and skill, and while farmers and other students of agriculture 

 cannot all be analytical chemists, they should all be able to under- 

 stand the meaning of a chemical analysis if it is reported without 

 unnecessary complications. The author's experience in practical 

 agriculture and close contact with progressive farmers desiring 

 to make practical application of scientific information revealed to 

 him the fact that some of the common methods of reporting analyses 

 of soils and fertilizers are extremely confusing, if not positively 

 misleading. Thus, it is common to report the analysis of potassium 

 chlorid (KC1) in terms of potash (K 2 O), notwithstanding the fact 

 that the material analyzed contains no oxygen. Sulfur in soils is 

 usually reported as sulfur trioxid (SO 3 ) , although the sulfur may 

 exist in the form of sulfid or as organic sulfur. Still more confusing, 

 very misleading, in fact, is to report in terms of calcium oxid (CaO) , 

 or quicklime, all calcium found in the soil, even though it may 

 exist only in acid silicates, and, instead of the soil containing any 

 lime in any form, it may require an application of some form of 

 lime to correct the existing acidity. 



The only kind of lime which exists in the soil in the agricultural 

 sense, that is, lime which has power to prevent or correct soil 

 acidity, is limestone, either ordinary or magnesian; and this is 

 sufficient reason why limestone present should be reported as lime- 

 stone; and for the same reason soil acidity is reported in terms of 

 limestone required. Instead of reporting in terms of percentage and 

 leaving the computations to be made by every individual who de- 

 sires to use the data, the analytical results may be reported in the 

 more simple and usable form of pounds per acre or pounds per ton, 

 which are the common farm units of weight and measure. Manures 

 and fertilizers are applied in tons or pounds per acre, and they are 



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