Evening public ledger. [volume] (Philadelphia [Pa.]) 1914-1942, 1917-11-12
USE OF POTASH
FOR PLANT FOOD
Account of Tests Made at Agri-
cultural Experiment
Station
To The Editor Of the Evening Ledger:


Sir-My attention has been called to an
| article published in the EVENING LEDGER
| by william II. Johnston, in which he dis
cusses the possibility of the utilization of
| finely ground potash feldspar as a direct
| source of potash for plant food.
In this connection he calls attention to
| Bulletin No. 104 of the Bureau of Plant
| Industry, United States Department Of
Agriculture, by DR.. A. $. Cushman. In the
course of his remarks Mr. Johnston says:
THE experiments as a whole showed that
under the conditions of the tests the potash
| of finely ground feldspar appeared to be
virtually as available for plant food the
| ordinary soluble salts ordinarily used" He
also mentions that "a large proportion of
| the rock underlying the American continent
consists OF feldspar. much of which con-
| tains potash In varying proportions up to
lG.S per cent
'Thls latter statement. while unquestion-
ably made in good faith, is likely to lead
| a casual reader to form an utterly exag-
gerated idea to the amount of potash in
ordinary rocks and the ease with which it
can be secured. AS n matter of fact, ii is
| only here and there that fedspar can be
separated readily. in considerable guam
titles, from the associated rock minerals
and even then II usually requires a good
deal Of cobbling and much cost for labor
In order to effect sufficiently satisfactory
separation. One Is fortunate even then IL
| he secures a feldspar containing as much as
from 10 to II per cent OF potash. Further
more, much of this material must obviously
be transported long distances, and II must
| be finely ground, but when ground in this
| manner is II available to a practical ex-
| tent? This Is the important question in
volved.
This bulletin of the Bureau of Plant In
dustry Of the United States Department of
Agriculture was published while ! was still
| director of the Rhode Island Agricultural
Experiment Station. Upon its appearance
with other published matter from the de-
partment bearing upon the subject of the
Agricultural value of finely ground feldspar
| began to receive letters from farmers in
Rhode Island asking II they could not grind
the feldspathic rocks on their farms and
| use them advantageously and economically
as a source of potash. The inference that
this could be done was drawn from these
Government bulletins.
II seemed TO me. therefore, of the utmost
inonortance that the matter be put to a
crucial test as soon as possible, Accord
inly Dr. b. l.. Hartwell. chemist of the
| station. and +. r. Pember, one of his as
sistants, were detailed to conduct care
| full experiment with finely ground feldspar
This feldspar was fine that all of II
readily passed through sieve having 200
| meshes to the linear inch In other words, It
was an impalpable powder. Early European
| experiments had shown the practical worth
|
| AGRICULTURAL purposes. The assertion had
| nevertheless been made that feldspar ground
| with modern machinery such as that used
| I'm nroducing the material which passed
| throueh the 200-mesh sieve would be read
iiv available to plants even though the
coarser European product would not.
II seemed, therefore. important to usa
| ,ba enest material obtainable. The experi
ments were conducted with wheat, followed
| hw Tananese millet and finally by beans
| Jss,ting 90 represent the yield of the wbaat ;
| .,han neither feldspar nor potash salts ,va q
| wsad the Yields from the use of feldsna p
| j., ,he three tests made were log, IO8 ana
| ms. whereas, when the same amount ~
| notash in the German potash salts WA
psed the corresponding yields were lao
| Iae and l4s. In the case Of the japanese
,,,,,s, n,acing the yield without feldspar or
,n.ash at 100, the yields with three az.
| 49,, amounts Of, feldspar were Io4 IIs
| "a i,4: whereas where a corresponding
anno,,nt Of potash in sulphate Of potash was
sssS the Yields were 212. 20s and 24s. Con.
Srmatory results were also secured with
beans.
The following are the conclusions drawn
,rom this work by Doctor Hartwell and
| Mr.. Pember'
The finely ground feldspathic rock.
| which was used In the experiments -.
corded in this connection. was Of -
siieht value - = ee3rc, q rsedilx avpiI-
W g Z I. l q ~ III Az ~. q 4. ~: = y.