CALCAREOUS MANURES— THEORY. 43 



smoothly with a knife, and some of it is in appearance and texture more 

 like the chalk of Europe, than any other earth that I have seen in this 

 country. 



22. A specimen of the very rich " cane brake" lands in Marengo county, 

 Alabama, contained" sixteen per cent, of carbonate of lime. This is a kind 

 of prairie, of a wetter nature, from the winter rains not being able to run 

 off from the level surface, nor to sink through the tenacious clay soil, and 

 the solid stratum of lime-stone below. 



23. A specimen from the very extensive " Choctaw Prairie" in Missis- 

 sippi, of celebrated fertility, yielded thirteen per cent, of carbonate of lime. 



Several other specimens of different, but all of very fertile soils from 

 southern Alabama, and all lying over the substratum of soft lime-stone, 

 were found to be neutral, containing not a particle of lime in the form of 

 carbonate. These specimens were as follows— 



24. One from the valley cane land— " very wet through the winter, but 

 always dry in summer— and after being ditched is dry enough to be culti- 

 vated in cotton, which will grow from eight to twelve feet high." 



25. Another from what is called the best "post-oak land," on which trees 

 of that kind grow to the size of from two to four feet in diameter— having 

 but little underwood, and no cane growth — » thought to be nearly as rich 

 as the best cane land, and will produce 1500 lbs., or more, of seed cotton, 

 or fifty bushels of corn to the acre." 



26. Another from what is termed " palmetto land, having on it that plant 

 as well as a heavy cover of large trees growing luxuriantly. It is a cold 

 and wet soil before being brought into good tilth ; but afterwards is soft 

 and easy to till, and produces corn and cotton finely. The cane on it is 

 generally small : the soil from four to ten feet deep."* 



One more prairie soil only will be adduc^ed, from many analyses which 

 have furnished general results like the foregoing, (20 to 26) ; and this one is 

 given because it serves as a fair specimen of a very large class of the 

 prairie lands. It was selected by Dr. R. W. Withers, in 1835, and de- 

 scribed by him as follows : {Farmers' Register, vol. Hi., p. 498.) 



Soil of Greene county, Alabama, " from our open or bald prairie, [i. e., 

 totally without trees,] which has been cultivated for seven or eight years — 

 produces corn very well — nearly fifty bushels to the acre are now stand- 

 ing on the ground ; but cotton does not produce so well on it as on poor 

 . sandy soil. I feel very confident that this specimen is highly calcareous, as 

 there are many fragments of shells mixed with the soil, and the rock is not 

 two feet from the surface. Of all the specimens hitherto sent, this is the 

 one which will give the nearest approach to the general character of our 

 open prairie land in this part of the country." — This specimen was found 

 to contain 33 per cent, of carbonate of lime. 



The foregoing details, respecting lime-stone lands, may perhaps be consi- 

 dered an unnecessary digression, in a treatise on the soils of the tide-water 

 district. But the analysis of lime-stone soils furnishes the strongest evi- 



* It is proper to mention a circumstance which may have had some effect in remov- 

 ing the carbonate of lime from these Alabama soils, besides the more general causes 

 which will be traced in the next chapter. With these specimens of soil was sent a 

 collection of the small stones and gravel which were stated to be found generally through 

 these soils, and particularly in the clay sub-soil beneath. Among these there were se- 

 veral fragments of sulphuret of iron. This mineral, when decomposing in the earth in 

 contact with carbonate of lime, also decomposes the latter substance, and forms sulphate 

 of lime, (gypsum,) instead. It is well worth inquiry whether sulphuret of iron is gene- 

 rally found in these soils. It may be known by its great weight, and metallic lustre 

 when broken, (which has caused it often to be mistaken for silver ore,) and by giving 

 out fumes of burning sulphur when subjected to strong heat under a blow pipe. 



