26S •'^w Essay on Calcareous Manures. 



that agriculture was more scientifically practised ; that experi- 

 mental knowledge should not be relied on alone ; but that a par- 

 tial knowledge of chemistry, and other immediately connected 

 sciences, should be depended upon, rather than opinions which 

 have no other foundation than the changing ideas of successive 

 cultivators. The essay is wholly directed to those lands, now 

 barren, but which the application of calcareous manure will ren- 

 der fertile and profitable. The immense beds of fossil shells, 

 throughout the tide-water region of the Atlantic, afford great fa- 

 cilities for the manuring of such lands, and furnish, at once, a 

 cheap and excellent substance. Agriculturists residing in such 

 situations will be the most benefited by this work ; but the gen- 

 eral principles which it contains are appUcable, in a greater or 

 less degree, to every part of the country. 



The work is divided into three parts, viz : — Theory — Prac- 

 tice — and the Appendix. The two former are divided into 

 twenty chapters ; and the latter into notes applying to the two 

 former. After a few descriptive and explanatory chapters, the 

 author proceeds to discuss the following propositions : — 



" Proposition 1. Soils naturally poor, and rich soils reduced to poverty 

 by cultivation, are essentially different in their powers of retaining pu- 

 trescent manures : and, under like circumstances, the fitness of any soil 

 to be enriched by these manures, is in proportion to what was its natu- 

 ral fertility. 



" 2. The natural sterility of the soils of Lower Virginia is caused by 

 such soils being destitute of calcareous earth, and their being injured 

 by the presence and effects of vegetable acid. 



" 3. The fertilizing etiects of calcareous earth are chiefly produced by 

 its power of neutralizing acids, and of combining putrescent manures 

 with soils, between which there would otherwise be but little if any 

 chemical attraction. 



" 4. Poor and acid soils cannot be improved durably or profitably by 

 putrescent manures, without previously making them calcareous, and 

 thereby correcting the defect in their contribution. 



" 5. Calcareous manures will give to our worst soils a power of retain- 

 ing 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 author argues his subject Avith much originality, and the 

 results of his experiments are very satisfactory. We have 

 scarcely room to make any extracts, but we give the following 

 as the result of one : — 



" 1822. On a body of neutral soil which had been reduced quite low, 

 but was well manured in 1819, when last cultivated, gypseous marl was 

 spread on nine acres, at the rate of three hundred bushels. This ter- 

 minated on one side at a strip of muscle-shcU marl, ten yards wide — 

 its rate not remembered, but it was certainly thicker in proportion to 

 the calcareous earth contained, than the other, which I always avoided 

 laying on heavily, for fear of causing injury by too much gypsum. The 

 line of division between the two marls, was through a clay loam. The 



