434 AGRICULTURAL REPORT. 
Extended analyses of American food crops are needed, for those made 
in one country cannot be made arule for another country, where lati- 
tude, solar heat, and meteorologic influences are very different. The 
plant differs from the animal in this: the animal heat is developed by 
changes within the animal, and the latter is nourished and developed 
in proportion to that internal temperature, the sources of which are 
within; in plants the sources are without. The chemical changes which 
are continually going on in the growing plant are of that smaller 
amount which is not sufficient to increase the temperature of the plant ; 
the energy displayed in the growing plant is expended in the formation 
of lignine, starch, gum, sugar, and proteine bodies, and in the evolution 
of carbonic acid ‘and other gases, and thus none of it appears to warm 
the plant, except in those rare instances of infloreseence in a few spe- 
cies. It is the external temperature which warms the plant; and, as 
the solar heat augments or lessens, so do the physical processes of os- 
mose absorption, selection, &c., proceed with more or less energy as the 
external heat varies. Hence, before we can give a formula for what plants 
need, it will be necessary that a large number of chemical analyses 
should be made. The teachings of Liebig have been carried intu ex- 
perimental practice in France, by Ville, who started with the idea that 
the mineral elements of the soil are the true and only food of plants; 
and, if these minerals are not present or in sufficient quantity, they 
must be added; and that manures, therefore, must be chiefly mineral. 
To explain this practice a few preliminary observations should here be 
presented. The elementary forms of matter which plants require are 
narrowed down to fourteen, four of which are organic, and ten mineral 
or inorganic, viz, carbon, hydrogen, oxygen, and nitrogen, organic ele- 
ments which represent ninety-five parts ina hundred of the composition of 
plants; phosphorus, sulphur, chlorine, silicium, iron, manganese, lime, 
magnesia, soda, and potassa, minerai elements, rarely exceeding five 
per cent., but they are necessary and must be present. The organic 
elements are supplied, as follows: the carbon chiefly by carbonic ‘acid, 
partly by humus in the soil; the hydrogen and oxygen by water, (rain,) 
and the nitrogen by the nitrogen and the ammonia in the air, and by 
ammonia and nitrates in the soil. 
The inorganic elements, ten in number, are not equally absorbed by 
plants; some of them in’ so very small proportion that all soils are 
amply supplied with them; such are sulphur, silicium, manganese, and 
iron. In fact, of the whole series of elements, organic and inorganic, 
only four need to be added in quantity as a manure, namely, nitrogen, 
phosphoric acid, (phosphorus,) potassa, and lime. The phosphorie acid 
may be supplied by bones, apatite, phosphorite, coprolites, fossils, marls 
and remains, and greensand. The potassa from the primary or crystal- 
line rocks, as the granites and feldspathic rocks, which constitute chains 
of mountains, and yield 10 to 15 per cent. of potassa; from sea water, 
which, in detect of other sources, may, by Balard’s process, have its po- 
tassa extracted ; and from saline deposits rich in potassa, such as those 
at Stassfurth in Prussia. The lime from the usual sources of gypsum, 
marls, limestones, and other calcareous substances. Out of compounds 
containing these four elements, Ville forms his manure, which, because 
it supplies all that is needed, is termed by him the “ complete manure,” 
(engrais complet.) The proportions in the complete manure are: 
Pounds. Ounces, 
e 
Saperphosphate of lime iii 0 tks en ebe eee seeks ote wale ou veer 8 14 
Nitrate of potassa....-...---...--- 2 prensa) TE aE Sa eee aaa Ae 4 if 
