SUMMARY 279 



doubled by expressing the amount of phosphorus in the 

 latter way. 



Potash is sometimes called "equivalent to sulphate." 

 This also apparently increases the amount, almost doubling 

 the figures. 



For example, a fertilizer containing 1 per cent, nitrogen, 

 6 per cent, phosphoric acid, and 4 per cent, potash would 

 be expressed on the higher basis as 1.21 per cent, ammonia, 

 13.08 per cent, bone phosphate of lime, and 7.40 per cent, 

 potassium sulphate, and yet it might contain no ammonia, 

 no bone phosphate, and no sulphate of potash. 



In interpreting a fertilizer analysis the farmer need pay 

 attention only to the nitrogen, phosphoric acid, and potash, 

 and not be led astray by the more attractive higher figures. 

 It is only just to say, however, that most of the fertilizers 

 now r offered for sale by reputable concerns are honest goods 

 with the guaranteed analysis well stated. 



213. Summary. — Analyses of soils and fertilizers are 

 usually reported in terms of the oxides of the elements, 

 basic or acid, as the case may be. Although the use of the 

 elements alone in reporting such work seems more logical 

 and consistent, it is not customary for various practical 

 reasons. 



The analysis of soils for the purpose of discovering 

 fertilizer deficiencies is not very satisfactory. Many methods 

 have been devised, some for determining the total amount 

 of any element present, and this can be accurately done; 

 some for determining the amount of available material, and 

 this can not be accurately done. Taken in connection with 

 other information, soil analysis, more particularly of the 

 total constituents, is of help to the expert in interpreting 

 soil deficiencies. The value of a soil analysis is very great 

 for the purpose of studying the changes in soils, the effect 

 of fertilizers and crops, in comparing soils, and in special 

 scientific work in soil chemistry. The results of this kind 

 of work can later be applied in a practical way. 



Tests for determining the amount of lime required by a 

 soil to correct acidity are in use and one in particular is 

 approximately accurate, although it is better fitted for 



