Issued May 9, inii. 



United States Department of Agriculture, 



BUREAU OF SOILS CIRCULAR No. 26. 

 MILTON WHITNEY, Chief. 



EXAMINATION OF SOIL SAMPLES. 



Several hundred letters are received annually by the Bureau of 

 Soils asking for more or less specific information regarding samples 

 of soils sent in for examination. A review of this correspondence 

 shows that, while all of the States and Territories are represented, 

 about half of the requests come from New York, Pennsylvania, 

 Texas, Virginia, California, Illinois, Maryland, New Jersey, Wash- 

 ington, and Florida, in about the order named. 



It appears that in about one-third of the cases submitted for an 

 opinion the requests are for advice as to crop adaptation, about one- 

 third for information regarding fertilizer requirements, and one- 

 third for a definite chemical examination to determine the amount of 

 some one or more of the mineral elements including potash, phos- 

 phoric acid, calcium, and magnesium of nitrates, of alkali, and of 

 the lime requirement. About 1 per cent of the requests are for spe- 

 cific information requiring a special laboratory examination for the 

 purpose of determining harmful constituents, usually suspected to 

 be of organic nature. 



In the event that the examinations show obscure conditions, and 

 especially if they indicate the presence of deleterious substances of 

 organic nature, and with all samples submitted for the specific pur- 

 pose of determining harmful organic constituents suspected of caus- 

 ing abnormally low yields a long and often tedious investigation is 

 required, based upon the methods described in part in Bureau of 

 Soils Bulletin 74, 



In very few cases is it considered necessary or advisable to make a 

 chemical analysis by any one of the well-known acid digestion 

 methods, as the result of such an examination appears to throw little 

 light upon the adaptation of crops to soils; and as far as yield is con- 



90517 Cir. 26 11 



