APPENDIX 



THE METHODS OF SOIL ANALYSIS 



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1 



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How to take a sample of soil. Owing to the variation in com- 

 position of the soil at different depths it is particularly necessary 

 that the sample should always be taken to the same depth and with 

 a tool making a clean vertical cut. Samples taken with a spade are 

 of very doubtful value and do not justify any lengthy examination. 

 The simplest tool is shown in Fig. 41 and consists of a steel tube 

 2 in. in diameter and 12 in. long, with a f in. slit cut along its length 

 and all its edges sharpened. The tube is fixed on to a vertical steel 

 rod bent at the end to a ring 2 in. in 

 diameter, through which a stout wooden 

 handle passes. A mark is made 9 in. from 

 the bottom so that the boring process 

 can be stopped as soon as this depth is 

 reached. On withdrawing the tool the 

 core of soil is removed by a pointed iron 

 rod. Five or six samples should be taken 

 along lines crossing the field so as to get 

 as representative a sample as possible; 

 the whole bulk must then be sent to the 

 laboratory. The student should carefully 

 learn how to do this so that he can take 

 samples for himself. Samples should not 

 be taken from freshly ploughed or recently manured land. 



The analysis. On arrival at the laboratory the soil is spread out 

 to dry, and is then pounded up with a wooden pestle and passed 

 through a 3 mm. sieve. The stones that do not pass through, and 

 the fine earth that does, are separately weighed, and the proportion 

 of stones to 100 of fine earth is calculated. Subsequent analytical 

 operations are made on the fine earth. 



Moisture. Four or five grams of the soil are dried at 100 C. till 

 there is no further change in weight. 



Organic matter. No accurate method of estimation has yet been 

 devised. It is usual to ignite at low redness the sample dried as 



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Fig. 41. Soil borer. 



