354 SOILS. 



from the prompt change in vegetation whenever it is intro- 

 duced into soils deficient in it. In discussing the results of 

 soil analysis, its consideration is of first importance in fore- 

 casting correctly the adequacy or inadequacy of other soil in- 

 gredients ('see chapter 20, page 379). For in general, we find 

 that lower percentages of potash, phosphoric acid and nitrogen 

 are adequate, when a large proportion of lime carbonate is 

 present. This has already been referred to in connection with 

 the table of soils of low percentages, given above. In the in- 

 terpretation of results obtained by analysis this point must al- 

 ways be kept in view; and in the numerical statements made 

 below, it must be understood that they refer to virgin soils 

 sufficiently supplied with lime to assure a constant excess of 

 lime carbonate, maintaining the conditions of nitrification and 

 insuring the absence of acidity. (See chapter 9, page 146). 

 Potash. In respect to potash, the writer was led by his 

 early investigations in the State of Mississippi to conclude that 

 less than one- fourth of one per cent (.25) of potash consti- 

 tuted a deficiency likely to call for early fertilization with 

 potash salts; while as much as .45% of the same seemed to 

 cause the land to respond but feebly to such fertilization. He 

 has not found it necessary to revise materially that early con- 

 clusion, whether from his own work or from that of others. 

 Within the last decade, Prof. Liebscher of Gottingen 1 has ar- 

 rived at this identical figure from analyses made of soils upon 

 which he had conducted a seven-year series of fertilizer tests; 

 he having found that potash fertilization produced no sensible, 

 or at least no paying results on land giving that figure, 

 and otherwise well provided with plant-food. The different 

 (lower) figures given by Schloesing, Risler and other French 

 chemists in discussing the soils of France, are doubtless due to 

 the weak acid and short period of digestion employed in the 

 analysis; an unfortunate discrepancy of methods which pre- 

 cludes any direct comparison of results. 



These figures apply both to the arid and the humid regions in the 

 temperate zones. In the tropics we find very much lower percentages 

 quoted as adequate ; thus in the laterite soils of India and Samoa, 



1 Untersuchungen uber die Kestimmungdes Diingerbediirfnisses cler Ackerboden 

 und Kulturpflanzen, von G. Liebscher; Journal fur Landwirtschaft 43 < 1895), 

 Nos. i & 2, pp. 48-216. 



