II. METHODS FOR THE ANALYSIS OF SOILS. 



1. Directions for Taking Samples, 

 (a) METHOD 1. OFFICIAL. 



Remove surface accumulations of decaying leaves, etc., and take samples with 

 a soil tube or auger to the desired depth. If the tract to be studied is not of 

 uniform character, divide into smaller tracts, that each may be uniform, and 

 from such tracts take five or six representative samples to the depth of 6 

 inches, or to the change between the surface soil and the subsoil, in case such 

 change occurs between the depth of 6 and 12 inches. In no case is the sample 

 to be taken to a greater depth than 12 inches. If the surface soil extend to a 

 greater depth, a separate sample below the depth of 12 inches is to be obtained. 

 If the surface soil extend to a depth of less than 6 inches, and the difference 

 between it and the subsoil is unusually great, a separate sample of the surface 

 soil should be secured, besides the one to the depth of 6 inches. Mix the 

 samples of each depth thoroughly and take subsamples of 2 to 4 pounds, drying 

 the latter in a well-aired, cool place. 



The depth to which the sample of subsoil should be taken will depend on cir- 

 cumstances. It is always necessary to know what constitutes the foundation 

 of a soil to the depth of 3 feet at least, since the question of drainage, resist- 

 ance to drought, etc., will depend essentially upon the nature of the substratum. 

 But in ordinary cases 10 or 12 inches of subsoil will be sufficient for the pur- 

 poses of examination in the laboratory. The sample should be obtained in other 

 respects precisely like that of the surface soil, while that of the material under- 

 lying this subsoil may be taken with less exactness, perhaps at some ditch or 

 other easily accessible point. Mix and subsample as above. The sampling should 

 be done preferably when the soil is reasonably dry. 



It is recommended that the weight of a given volume of the soil as it lies 

 in the field be taken for calculating the percentage results obtained by analysis 

 to pounds per given area of the soil. 



(b) METHOD 2. PBOVISIONAL. 



Remove surface accumulations of decaying leaves, etc., and take samples with 

 a soil tube or auger to the desired depth. All samples of soils taken for 

 analysis should be composite and should be composed of representative samples 

 taken from at least five different places in the field sampled, each individual 

 sample to be a column of uniform soil extending through the stratum sampled. 



One composite sample should be taken from each important and distinctly 

 different soil stratum to a depth of 40 inches, or 1 meter, including a composite 

 sample from the arable stratum, or plowed soil, usually about 6 inches or 15 

 cm deep. 



If the plow line and the subsoil line coincide, and the subsoil is a fairly uni- 

 form stratum to the depth of 40 inches, then only two composite samples need 

 be taken, one of the arable soil and one of the subsoil. But if the subsoil line 

 is lower than the plow line and not below 40 inches, then both strata below the 



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