256 SOURCES OF SUPPLY OP AZOTE. 



of the importance of the sources of supplies of azote which will be 

 indicated.* 



Azote is mostly derived by plants from the soil and through 

 their roots. This is made evident by the obvious effects of all 

 putrescent manures, and the superior effects of those known to be 

 richest in azote. But it seems from some delicate and careful ex- 

 periments of Boussiugault's, that some particular plants, and, as 

 far as known, those belonging to the leguminous or pod-bearing 

 kind only, possess the power of also deriving azote from the atmo- 

 sphere. This power, if certain, would be enough to explain the 

 reason of the well known and peculiar value of leguminous plants 

 as manuring crops. * 



This eminent chemist and practical agriculturist sowed known 

 quantities of the seeds of different kinds of plants in artificial soils, 

 composed of either burnt clay or silicious sand, which had been 

 deprived of all azotic and other alimentary manuring principles by 

 sufficient exposure to a high degree of heat. In other cases, young 

 plants were removed from natural soils to such artificial soil, after 

 being completely cleared of all adhering earth. The vessels con- 

 taining the soils and plants were protected from receiving dust, or 

 anything else from without, and the seeds and plants therein were 

 duly moistened with distilled water. The plants, in some cases, 

 stood until mature; in others, for shorter terms. Finally, the 

 several kinds were analyzed, as had been done of the like kinds of 

 seeds, or transplanted plants, from which they grew, and the differ- 

 ences of contents noted (omitting the ashes, or inorganic parts), 

 as shown in the following summary of the results : 



* Ordinary barn-yard manure, which has been heaped, partially fer- 

 mented, and is half rotted, is the kind which M. Boussingault used on his 

 farm and in his analyses. Such manure was considerably richer than ours, 

 made with fewer and worse-fed cattle, compared to the large proportion of 

 litter, and used without being heaped or fermented. His manure, also, in 

 a heap, would necessarily have less water. Yet he estimates the water alone 

 at from 75 to 80 per cent, of his manure. Of course, when dried, as stated 

 in the preceding table, 100 parts of such manure is equal to at least 400 

 parts in the heap ; and, therefore, these 400 parts in ordinary condition 

 contain only 1.95 parts of azote or less than the half of one per cent, 

 serving to constitute the principal enriching value of the manure. 



