BULLETIN OF THE BUSSEY INSTITUTION. 359 
justify the English custom of adding salt to grain-fields to hinder 
the growth of straw, 7. e. to prevent the leafy-part of the crop 
from becoming too rank. All that is really known thus far is the 
empirical fact that the growth of some plants (such as wheat) is 
hindered by saline fertilizers on soils where the growth of other 
plants (like beets and cabbages) is promoted even by tolerably 
heavy dressings of them.* It is not impossible that heavy dress- 
ings of the chlorides of sodium or potassium may exert a germicide 
action in some cases — whether for harm or good depending natu- 
rally on circumstances in each particular instance. It is certain, at 
all events, that in the old European system of making saltpetre in 
beds, the presence of more than a small proportion of salt in the 
earth was found to distinctly hinder nitrification. Some such ac- 
tion as this may have been the original motive of the old Swiss 
practice of adding salt to dung-liquor to improve it. As everybody 
knows, salt has often been employed in heavy doses for clearing 
land from weeds, worms, and insects. 
D. — Potassic manures are specially acceptable to leguminous 
crops. 
Perhaps nowhere else in the world has the merit of potash as a 
manure for clover been more clearly and generally recognized than 
in this country. Indeed it has been accepted as an article of faith 
by many generations of New England farmers that ashes will 
‘¢ bring in” clover, as a matter of course, when applied to pastures 
or mowing-fields — a fact which has been illustrated and, so to say, 
methodized in recent years by Messrs. Lawes and Gilbert in their 
well-known experiments on the effects of different manures on the 
composition of the mixed herbage of meadow-land. Forty or fifty 
years ago, when red clover was frequently or even habitually grown 
in the immediate vicinity of Boston in admixture with Timothy as a 
source of hay, it was a matter of common belief and experience that 
the crop would be certain to succeed if only some wood-ashes could 
be procured to sow with the clover-seed. It is true that clover is no 
longer grown hereabouts, and that no pains are taken to favor it, 
- though there is small reason to believe that this plant has been dis- 
carded by our farmers because they are unable to produce it.{ But 
* Compare J. Lehmann, ‘‘ Hoffmann’s Jahresbericht der Agrikultur-Che- 
mie,” 1862-63, 5. 247. 
+ See ‘‘ Recueil des Mémoires sur la Formation du Saltpétre, in Mémoires 
des Savans Etrangérs,” 1786, vol. XI. passim. 
t The reasons why clover is no longer grown around Boston are no doubt 
