CHAPTER XVI 

 CHEMICAL ANALYSIS OF SOILS 



No PHASE of soil science has received as mucli popular rec- 

 ognition as chemical analysis, nor is any other technical soil 

 procedure so little understood in general and at the same 

 time so greatly overrated. Many persons feel that a soil 

 analysis should completely solve the many problems, both 

 theoretical and practical, regarding the economic management 

 of the soil, especially as to its fertilizer needs. In the light 

 of such general misunderstanding in regard to the research 

 and applied value of chemistry to soils, a consideration of the 

 question seems opportune at this point, especially as the dis- 

 cussion of the phenomena of absorption and the characteristics 

 of the soil solution have just been presented. 



For convenience in treatment, chemical analyses, as applied 

 to soils, may be grouped under two heads — total or bulk 

 analyses and partial or extraction methods. In the former the 

 total amount of certain constituents are determined regard- 

 less of their chemical combinations and character. In the 

 latter group of methods only a portion of certain important 

 materials are removed and analyzed, the chemical combina- 

 tion being to a certain extent a factor in the amount of any 

 constituent extracted. 



165. Bulk analysis— organic carbon and nitrogen.^— 



^The sampling of the soil is an important consideration in any 

 analytical work. The sample should be representative and is "best 

 taken with a soil auger. In sampling small areas, such as plats, a num- 

 ber of boriyigs are usually made to the depths required and thoroughly 

 mixed. This composite is quartered until a sample of the required size 



