864 STATE BOARD OF AGRICULTURE. 



silica, and perhaps to the insoluble organic matter. There is probably 

 then practically no active acidity in the mineral soils, but only negative. 

 Exceptions to this general statement are probably very few. 



In the peats and mucks, however, the formation of the organic acids is 

 probably quite rapid, and consequently these soils may contain per- 

 manent active acidity, as well as permanent negative acidity. 



One more point before concluding. If it is true — ivhich is beyond any 

 doubt — that ichen a soil is treated with an excess of acid, acid salt and 

 neutral salt, the supernatant liquid contains very little add or acid salt, 

 ichile the soil inass itself retains a large amount of the acid or acid salt 

 {or a substance lohich greatly increases the lime requirement), then the 

 question rises, can any of the present soil acidity methods which em- 

 ploy neutral salts and use only the supernatant liquid, give the true 

 lime requirement of the soil? This is indeed a question of g^'eat and 

 fundamental importance and must not be ignored. 



Note: After the foregoing report was completed and submitted for 

 publication there were received from the Rhode Island Experiment Sta- 

 tion samples of twelve different soils, with a request from Mr. F. R. 

 Pember to determine their lime requirement by the freezing point 

 method. As the cultural history of these soils is known, their results 

 on lime requirement are of high interest and great significance from the 

 standpoint of the reliability and value of the freezing point method. 

 The data obtained are detailed in the following table : 



TABLE 14. LIME REQUIREMENT OF SOILS 



Number Pounds CaO 



of soil. per 



2,000,000 

 pounds soil. 



1 10,096.2 



2 6,730.8 



3 15,705.2 



4 27,000 



5 15,705.2 



6 8,974.4 



7 560 . 9 



8 .. 560.9 



2oo!;;;;;;;;;!;;:;;!;;;;;;.!.;.; 8,413.5 



201 8,413.5 



202 6,730.8 



203 6,730.8 



It will be at once seen that the different soils took up entirely dif- 

 ferent amounts of lime; the quantity ranging from 560.9 pounds CaO per 

 acre in the case of soils No. 7 and 8 to 27,000 pounds in the case of soil 

 No. 4. 



Soils No. 7 and 8 are sand, while all the other soils may be classed as 

 very fine sandy loam. Since the texture of the latter soils is more or 

 less the same, their different lime requirement must be due to the dif- 

 ference in the cultural treatment they have received. In other words, 

 the great variation in the lime requirement of these boils, which originally 

 probably belonged to the same series and type, is caused by the different 

 cultural treatment they have received. Indeed, their cultural history, 

 as indicated by the following communication from Mr. Pember, proves 

 such to be the case: 



"The soil of samples No. 1 and 3 came from field plat No. 23 in the 

 spring of 1915 and was stored under greenhouse conditions until used. 



