10*2 IJiiK 1\i (iiih'ciiii'iiix nf (\rt(i'ni Soils 



lalciuiii faibonatc 'I'lic results, coutained iii Tabic Xl.sliow the very 

 great rapidity witli wliich tiiis change can proceed in the presence of 

 carbonate, the change having reached completion within the first 20 

 days. The amount of nitrification taking place in the soil without 

 lime was also quite appreciable in spite of the lack of free carbonate, 

 although calcium may bo libeiati'il IVdni tlic mineral or the organic 

 soil constituents. 



The main effect of an application of carbonate to thi.s soil consists 

 apparently in speeding-up both of ammonification and nitrification. 

 but on account of the reasons stated above, the formei- action is probablv 

 the more important. 



The Behdioii helween Soil Acidity and Natural Vegetaiimt. 



While the conventional method of soil analysis with reference to 

 lime generally consists in an estimation of carbonates, there are many 

 instances in which this procedure fails to give an index to differences 

 often apparent in the field. This applies to the distribution of plants 

 on many of the heaths and commons throughout the country and also 

 to a certain extent to the vegetation prevailing on much old gra.ss land. 

 As an instance, the case of the Harpenden Common may be cited, where 

 carbonate determinations in soil samples from parts of the Common 

 have failed to provide data that would help to grade the soils as to their 

 relations to plant growth. .KW these soils react acid to litmus, hut 

 examination shows that from place to place, vegetations occur in which 

 white clover, fescues, gorse, sorrel, bracken, etc., predominate. 



k large number of these soils have now been examined by means 

 of the bicarbonate method described al)()ve and we have been enabled 

 to classify tliem in terms of acidity and vegetation. A few of these 

 results are given below to illustrate some of the differences encountered. 

 Photographs of typical turfs are shown in Plate \. 



Table XII. Lime Requirement as related to Vegetation. 



