■ARDEN 



JOURNAL 



OF THE 



ROYAL AGRICULTURAL SOCIETY 

 OF ENGLAND. 



THE VALUE OF SOIL ANALYSES TO THE 

 FARMER. 



Since the scientific man first turned his attention to agriculture, 

 few questions have been more generally addressed to him than 

 requests to make analyses of particular soils and report the 

 cause of their excellences or defects. It would seem to be so 

 straightforward a problem ; on soil A the wheat always stands 

 up, on soil B it is apt to blight and go down ; why cannot the 

 chemist analyse them both and say what valuable constituent 

 B lacks, or what injurious substance it contains to so affect the 

 wheat. The chemist, however, has rarely been able to answer 

 such a question ; in many cases when he has given an answer 

 it has not proved of any value in practice because, in all prob- 

 ability, he mistook some accidental variation between the two 

 soils for. a causal difference. 



In the first place there is very little difference in composi- 

 tion between one crop and another, between a healthy and 

 a diseased one ; all plants contain the same small range of 

 elements drawn from the soil — nitrogen, phosphoric acid, 

 sulphur, chlorine, soda, potash, lime, magnesia, with a trace of 

 iron, and sometimes silica — and in very much the same pro- 

 portions. These same elements occur in all soils with but 

 small variations in the proportions. Few soils contain as much 

 as ()*5 per cent, or less than O'l per cent, of nitrogen, and other 

 important elements vary even less. Moreover, small as these 

 amounts may seem, they are far more than the crop requires ; 

 the soil over an acre down to the depth of nine inches weighs 

 about 1,000 tons, so 0*1 per cent, would mean about 10 tons of 

 nitrogen to the acre. Now a big crop of wheat would not 

 remove from the soil more than about 70 lb. of nitrogen per 

 acre ; mangels might take away twice as much, but still a trifling 

 amount compared with the stock in the soil. Yet with all this 



VOL. 73. B 



