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sphere to leguminous plants, it will be easy for us to profit by this 
newly acquired knowledge in order better than before to preserve 
our lands in a state of suitable fertility. Suppose, for example, that 
clover, let us say, has been sown with any cereal and that it is left to 
erow freely, after the harvest; this clover will take a certain quan-_ 
tity of nitrogen from the air, by the help of the nodules on its roots. 
If this clover is plowed under before the next time of sowing, in the 
spring or autumn, so as to serve as a green fertilizer, we shall have 
obtained, with no other expense than the price of the seed, a manure 
derived wholly from the air of the atmosphere. 
This practice, first recommended by Ville, has been recently shown 
by Deherain to have another advantage quite as important. By keep- 
ing the surface of the soil in a state of constant evaporation the inter- 
polated cultivation of the clover diminishes the drainage to a notable 
extent; all the nitrates, which then are formed in large quantities and 
which would be lost if the earth remained uncovered, are held and 
assimilated, being rendered insoluble by the vegetation, and when 
plowed under will augment by so much the more the natural reserves 
of the soil. 
This method, whether we consider it as the cultivation of a fallow 
field or whether we call it “sidération,”’” as proposed by Ville, 
affords two advantages of primary importance—it prevents in a great 
measure the losses due to excessive nitrification of the soil in autumn, 
and restores to the earth a certain quantity of nitrogen which has 
passed from a gaseous state to the state of organic matter. I do not 
think it an exaggeration when I say that the gain from this practice 
alone is equivalent to a strong artificial manuring of the soil, and it 
may sometimes even attain a value of many hundred franes per hec- 
tare, which will be realized in subsequent crops. 
Finally, among other examples of the application of this new 
knowledge there is a most curious fact which has just been pointed 
out by Salfeld, in Ger many, and which, if proved, will be a further 
confirmation of the immortal doctrines of Pasteur. After clearing 
a peat bog situated on the banks of the Ems, on the frontier of Hol- 
land, horse beans and vetches were sown. The soil was everywhere 
enriched with mineral fertilizers, but on one part only of the field a 
small quantity of good arable earth was spread, in the proportion of 
about 40 kilograms to the are.” 
The effect of the addition of this latter element was, as it appears, 
most surprising; under its influence the crop was doubled. This 
result is, in Salfeld’s opinion, similar to the results obtained by 
Hellriegel and Wilfarth in their laboratory experiments; if this 1s 
really so—and it is possible—there will be in ‘the near future a new era, 
a sort of revolution, so to speak, in practical agriculture. 
Perhaps the time is not far distant when our farmers will add to 
the fertilizers of commerce |the so-called soil improvers and complete 
manures, ete.—C. A.] true culture broths, prepared according to the 
methods in use in microbic researches, and which will furnish to 
plants the germs of organisms capable of fixing nitrogen [the nitro- 
gen fixers], or, perhaps, others still, favorable also to their develop- 
aThis medical term for atrophy or roncineation "does not seena quite appro- 
priate in this case.—C. A. 
vb The are is about 119 square yards, or 100 square meters, or 1,071 square feet. 
