QUANTITY OF LIME TO BE APPLIED TO THE SOIL. 381 



Few investigations have as yet been made in regard to the proportion 

 of lime which exists in the soil in the state of humate. It has gene- 

 rally been taken for granted — either that a soil was destitnte of lime if 

 it exhibited no sensihle effervescence with dilute muriatic acid.-^or 

 when further research was made, and the quantity of hme taken up by 

 this acid rigorously determined, that the whole of this lime must have 

 existed in the soil in the stale of carbonate. That this is not necessarily 

 the case, however, appears to be proved by some recent examinations 

 of certain soils in Normandy, which contain as much as 14 to 15 per 

 cent, of lime, and yet exhibit no effervescence, and contain no carbo- 

 nate. The whole of the lime is said to be in the state of humate. 



M. Dubuc, who has published the analyses of these soils, attributes 

 much of their fertility to the presence of the humate of lime. Thus he 

 says that the soils of 



Containing per cent. 

 Of Carbonate. Of Humate. Yields of Wheat. 



Lieuvin, Neubourg, and Sistot, 18 to 20 12 to 15 fold. 



Pavilli 5 8 to 10 " 



Bieville 24 8 to 10 " 



ClayofOuche 1 4 to 5 *' 



The first two yielding a wheat crop every second year, the third only at 

 longer intervals. 



Whatever degree of influence on the fertility of the soil it may ap- 

 pear proper to attribute to the existence of lime in the soil in the state 

 of humate, it is manifestly of some importance that its presence in this 

 state of combination should be more frequently and more carefully 

 sought after. 



The only one of the above compounds which is usually added to the 

 land, for the purpose of producing the ordinary effects of lime, is the 

 carbonate. Gypsum is applied only in small quantity for certain spe- 

 cial purposes, and does not always produce a sensible effect. It is in- 

 capable, therefore, of performing those jjurposes in the soil which are 

 served either by quick-lime or by the carbonate. The humate of lime 

 is probably formed in our lime composts, especially when much vege- 

 table matter is contained in them, and may thus be not unfrequentlv 

 applied directly to the land. 



^ 10. Of the quantity of lime which ought to he added to the soil. 



The quantity of lime which ought to be added to the soil is dependent 

 upon so many circumstances, that it is impossible to state any general 

 rule by which, in all cases, the practical man can safely regulate his 

 procedure. 



1°. To soils which contain no lime, or to which it is added for the 

 first time, a larger dose must be given. 



We have seen that a certain minim.um portion of lime is indispensa- 

 ble to a productive soil. If we suppose this smallest quantity to be no 

 greater than in the surface of the marsh lands of Holstein (p. 378) — 

 then with a soil six inches in depth, which contains no lime, we ought 

 to mix a ton and a half, say 40 bushels of slaked lime, and by succes- 

 sive yearly additions to supply the annual waste. 



But to mix this feeble dose of lime intimately with the soil to a depth 

 of six inches would obviously require an expenditure of labor which 



