BULLETIN OF THE BUSSEY INSTITUTION. 271 
amount of nitrogen thus retained is usually exceedingly minute, and 
the experiments with carbonate of potash, and with sulphate of potash 
just alluded to, make it evident that the nitrogen which is so freely 
taken up by plants that have been manured with wood-ashes, cannot all 
have come from the paltry store within the ashes, but must have been 
derived for the most part from some other source. JZven the ashes 
produced in the process known as paring and burning, doubtless act 
_ like ordinary wood-ashes upon the organic matters in the unburnt soil, 
and in that which has been half burnt or merely charred. 
A specially noteworthy instance of the class now in question is 
found in the use of the so-called cendres:de marais, or ashes of 
stable-manure, upon a rich tract of marsh land on the southwestern 
sea-board of France (Bobierre, op. cit.. pp. 122, 510). In default 
of other supplies of fuel, the inhabitants of that district burn the dung 
and litter of their farm animals, after it has been formed into cakes 
and thoroughly dried; and although little. or no care is taken to 
protect the ashes from rain during the winter months, the fertility of 
the rich alluvial soil of the marshes is nevertheless kept up by means 
of heavy dressings of these ashes. ‘The marsh lands in question are 
particularly rich in humus, and the fact that they yield an abundant 
supply of nitrogen to crops when manured, as has just been stated, 
with nothing but the ashes of dung, is really little more remarkable 
than the facility with which such soils naturally supply the nitrogen 
necessary for the support of wild plants when no manure of any kind 
has been applied to them. There can be no doubt, for instance, but 
that the fertility of the famous “black earth” of Southern Russia is 
largely dependent upon the nitrogenous matters that are contained in 
it, and the same remark is true of many soils in our own country. In 
several samples of prairie soils from Illinois, Dr. Vcelcker found note- 
worthy amounts of nitrogen ;* and specimens of soil from the famous 
bottom lands of the Scioto River,t on which heavy crops of grain had 
been grown without interruption for a long term of years, were found 
to contain from 2 to 11% of organic matter. “The amount of nitro- 
genous compounds contained in this organic matter is undoubtedly 
* See Caird, James, “ Prairie Farming in America,” New York, Appleton 
& Co., 1859, Appendix. 
Tt Reported upon by D. A. Wells, “American Journal of Science,’ 1852, 
14. 11. 
