266 LIME IN COMPOST HEAPS. 



temperate regions, the production of nitric acid is rapid in propor- 

 tion. " (Johnston, p. 161.) 



Thus, and in other modes, by the presence and agency of calca- 

 reous earth, it may be supposed that nitrogen (or azote), which is 

 the essential element of all rich putrescent manures, is continually 

 produced from the atmosphere ; and that the results, in nitrates, 

 are given to growing plants, by which they obtain and assimilate 

 the necessary nitrogen, which could not be otherwise obtained, ex- 

 cept from large supplies of rich animal manures. 



If these views are sound, they lead to most- important conse- 

 quences, and suggest the existence of before unknown enriching 

 and fructifying agencies of lime, continually at work, in drawing 

 rich manure from the air, and giving the supplies to each successive 

 crop of growing plants, so long as the lime and organic matter re- 

 main together in the soil. 



These views also serve to throw much light on some opinions 

 and facts in reference to the benefits of lime, which I formerly 

 brought before the public, because of their interest, but of which 

 the causes were then left in all their obscurity. One class of facts 

 were presented in the very light limings of La Sarthe, in France, 

 of about 11 bushels only to the acre (though repeated in every 

 round of four crops), and showing undoubted good effects. This 

 was stated in Puvis 7 " Essay on Lime/'* which I translated and 

 published in the third volume of the " Farmers' Register." The 

 other facts referred to, doubtless were produced by that publication. 

 Mr. Peter Mellett, of Sumpter, S. C., pursued a similar course of 

 liming, and even with still lighter though more frequent dressings, 

 giving but 2J bushels to the acre, annually, and yet with satisfac- 

 tory results, and manifest and progressively increasing improve- 

 ment of both land and crops. f The process in both cases was to 

 form compost heaps of alternate layers of earth, putrescent manures, 

 and lime in very small proportion. In both cases, the evidences of 

 the results seemed unquestionable. Yet to me, the reported effects 

 then seemed to exceed the operation of all the then known causes, 

 in enormous disproportion. But the difficulties of comprehension- 

 will be removed by explanations suggested by the passages quoted 

 above. These compost heaps were in fact nitre-beds ; and the lime 

 acted much less by its quantity, and directly, as manure, than by 

 inducing the formation of nitrates, and thereby furnishing supplies 

 of nitrogen to the crops. Another circumstance strengthens this 

 conjecture. Puvis states of this practice, which was extensively 



* " Des differens mojjens d'amender le sol," in the " AnnaUs d? Agriculture 

 Fran$aise," for 1835-6. 



f These facts were more fully stated in my "Report of the Agricultural 

 Survey of South Carolina," made in 1843, under the order and appoint- 

 ment of the government of that State. 



