Review of Essays on Calcareous Manures. 



155 



careous earth in any other form, whether chalk, limestone, gravel, 

 wood ashes, or lime, although the two last have other qualities be- 

 sides the calcareous." 



" During the short time that lime can remain quick or caustic, 

 after being applied as manure, it exerts (as before stated) a solvent 

 power, sometimes beneficial, and at others hurtful, which has no con- 

 nexion with its subsequent and permanent action as calcareous earth." 



" These natural deposits of fossil shells are commonly, but very 

 improperly, called marl. This misapplied term is particularly ob- 

 jectionable, because it induces erroneous views of this manure ; other 

 earthy manures have long been used in England, under the name of 

 marl, and numerous publications have described their general effects 

 and recommended their use. When the same name is here given to 

 a different manure, many persons will consider both operations as 

 similar, and perhaps may refer to English authorities for the purpose 

 of testing the truth of my opinions and the results of my practice. 

 But no two operations, called by the same name, can well differ 

 more. The process which it is my object to recommend, is simply 

 the application of calcareous earth, in any form whatever, to soils 

 wanting that ingredient, and generally quite destitute of it ; and the 

 propriety of the application depends entirely on our knowing that 

 the manure contains calcareous earth, and what proportion, and that 

 the soil contains none." 



This being his object, he enforces the use of calcareous manures, 

 both by example and a well grounded theory. 



The comparative effects of the marl in various proportions, of sta- 

 ble and cowpen manure, and of marl mixed with manure, were fairly 

 tried, and tested with the product of land without addition. We 

 have not time to enter into the detail of the operations, and of the 

 several products. It is sufficient to say, that by the mixture of marl 

 and manure, the crop of corn was raised from twelve to thirty six 

 bushels per acre ; by eight hundred bushels of marl, from twelve to 

 an average of twenty three ; by four hundred and fifty bushels of marl, 

 from twelve to somewhat less than twenty seven ; that the mixture 

 and the last named dressing of marl alone, showed a subsequent in- 

 crease when corn returned in a four years' rotation, while the others 

 showed an average decrease ; that the wheat crops were increased 

 in about the same ratio ; but that clover, which before had not grown 

 at all, became a good crop on the marled patches. This was upon 

 soil which had before been in cultivation. Similar results followed 



