CHAPTER X. 



INTRODUCTORY AND GENERAL OBSERVATIONS ON MARL 

 AND LIME.* 



PROPOSITION 5. Calcareous manures will give to our worst soils 

 a power of retaining putrescent manures, equal to that of the 

 best and will cause more productiveness, and yield more profit, 

 than any other improvement practicable in lower Virginia. 



The theory of the constitution of fertile and barren soils, has 

 now been regularly discussed. It remains to show its practical 

 application, in the use of calcareous earth as a manure. If the 

 opinions which have been maintained are unsound, the attempt to 

 reduce them to practice will surely expose their futility ; and if 

 they pass through that trial, agreeing with and confirmed by facts, 

 their truth and value must stand on impregnable ground. The 

 belief in the most important of these opinions (the incapacity 

 of poor soils for improvement, and its cause) first directed the 

 commencement of my use of calcareous manures ; and the manner 

 of my practice has also been directed entirely by the views which 

 have been exhibited. Yet in every respect the results of practice 

 have sustained the theory of the action of calcareous manures; 

 unless indeed there be claimed as exceptions the injuries which 

 have been caused by applying too heavy dressings to poor and acid 

 lands ; and also the beneficial effects of proper practice being found 

 to exceed in degree what the theory seemed to promise. 



My use of calcareous earth as manure has been almost entirely 

 confined to that form of it which is so abundant in the neighbour- 

 hood of our tide-waters the beds of fossil shells, together with the 

 matrix, or earth with which they are found mixed. The shells 

 are in various states in some beds generally whole, and in others 



[* My views of the theory of fertilization have been presented in the pre- 

 ceding pages, (chapters ii. to ix. inclusive), precisely as they appeared in 

 1832 (and, in substance, at a still earlier time), the later additions being 

 all distinctly marked as such. This was deemed necessary to the main- 

 tenance of my claim of priority or of originality of opinions, some of 

 which, though then novel and unsupported by other authority, have since 

 been recognised as true, and are now generally if not universally received 

 by writers on agricultural chemistry. The like necessity will not apply to 

 the remainder of this work ; and therefore the distinguishing of later 

 additions to or alterations of the edition of 1832, will not be regularly 

 marked for distinction. Still it will be done whenever it may be required 

 for more clear exposition, or where the later dates of additions are deemed 

 of any importance to their purport. 1852.] 



