AN 



ESSAY 



CALCAREOUS MANURES 



PART SECOND-PRACTICE. 



CHAPTER I. 



INTRODUCTORY AND GENERAL OBSERVATIONS ON MARL AND LIME. REMARKS ON THi; 

 EXPERIMENTS TO FOLLOW. 



Proposition 5. Calcareous manures will give to our ivorst 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 main- 

 tained are unsound, the attempt to reduce them to practice will surely ex- 

 pose 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 l^y applying too heavy dressings to weak 

 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 neighborhood of our tide- 

 waters — the beds of fossil shells, together with the earth with which they 

 are found mixed. The shells are in various states— in some beds generally 

 whole, and in others reduced nearly to a coarse powder. The earth which 

 fills their vacancies, and serves to make the whole a compact mass, in most 

 cases is principally silicious sand, and contains no putrescent or valuable 

 matter, other than the calcareous.* The same effects might be expected 

 from calcareous earth in any other form, whether chalk, lime-stone gravel, 



* From later observation I have formed the opinion that the coloring matter of blue 

 marls is vegetable extract, chemically combined with the calcareous matter, of which 

 opinion the grounds will be stated hereafter. But still the amount of this vegetable ad- 

 mixture is too small to have much appreciable effect as food for plants ; and, practically, 

 the general position assumed abovo may yet bo considered as altogether true. 



