THE ANALYSIS OF VIRGIN SOILS. 



369 



We are thus led to the conclusion that the greater the clay 

 percentage in a soil, the more lime carbonate it must contain 

 in order to possess the advantages of a calcareous soil; and 

 that while in sandy lands lime growth may follow the presence 

 of only .10% of lime, in heavy clay soils not less than about 

 .6% should be present to bring about the same result. This 

 is apparent to the eye in that the dark-tinted humus characteris- 

 tic of truly calcareous lands, does not appear in clay soils until 

 the lime-percentages rise to nearly i % ; while in sandy lands a 

 much smaller amount (say .2%) will produce this effect. 



European Standards. It is of interest to consider, in connection 

 with preceding discussions, the estimates given by Maercker of Halle, 

 of the practical value of soils corresponding to chemical composition 

 as ascertained by analysis with strong acids, substantially in accordance 

 with the methods adopted by the writer. 



PRACTICAL, RATING OF SOILS BY PLANT-FOOD PERCENTAGES ACCORDING TO 

 PROF. MAKRCKF.K, HALLE STATION, GERMANY. 



It will be observed that according to Maercker's valuation, the aver- 

 age California soil is " rich " in potash and lime, but only " medium " 

 as regards its contents of phosphoric acid and nitrogen. In this respect, 

 and almost throughout, Maercker's ratings are in remarkable agreement 

 with those made by the writer as far back as 1860.' It also appears 

 that Maercker's figures for " normal" soils correspond to those of the 

 American humid regions ; the " arid " figures for potash and lime being 

 " abnormally " high. 



1 See discussions of analyses of Mississippi soils in the Report on the Agriculture 

 and Geology of Mississippi, 186*1; same in Rep. On Cotton Production, Tenth 

 Census, 1880, Vol. 5; also Appendix to the Report on the Experiment Stations of 

 the University of California, 1890, p. 163. 

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