Title Page

Group Title: Bulletin ;, 129
Title: How to conduct field experiments with fertilizers
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00071915/00001
 Material Information
Title: How to conduct field experiments with fertilizers
Series Title: Bulletin
Physical Description: p. 142-147 : ; 23 cm.
Language: English
Creator: Caldwell, G. C ( George Chapman ), 1834-1907
Publisher: Cornell University
Place of Publication: Ithaca N.Y
Publication Date: 1897
Subject: Fertilizers   ( lcsh )
Genre: non-fiction   ( marcgt )
Statement of Responsibility: by G.C. Caldwell.
Funding: Bulletin (Cornell University. Agricultural Experiment Station) ;
 Record Information
Bibliographic ID: UF00071915
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 23945011

Table of Contents
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        Page 147
Full Text

Bulletin 129. February, 1897.
Cornell University Agricultural Experiment Station.









Hon. A. D. WHITE,
Hon. B. F. TRACY,
Professor I. P. ROBERTS,
Professor G. C. CALDWELL,
Professor JAMES LAW,
Professor J. H. COMSTOCK,
Professor L. H. BAILEY,
Professor H. H. WING,
Professor G. F. ATKINSON,

S Trustee of the University.
President State Agricultural Society.
S Chemistry.
Veterinary Science.
- Dairy Husbandry.

I. P. ROBERTS, Director.
E. L. WILLIAMS, Treasurer.
E. A. BUTLER, Clerk.
M. V. SLINGERLAND, Entomology.
G. W. CAVANAUGH, Chemistry.
L. A. CLINTON, Agriculture.
B. M. DUGGAR, Cryptogamic Botany.

Office of the Director, 20 Morrill Hall.
The regular bulletins of the Station are sent free to all who request them.

24. The Pistol-Case-Bearer in Western New York.
25. A Disease of Currant Canes.
26. The Currant-Stem Girdler and The Raspberry-Cane Maggot
27. A Second Account of Sweet Peas.
28. A Talk About Dahlias.
29. How to Conduct Field Experiments With Fertilizers.

CORNELL UNIVERSITY, Ithaca, N. Y., Feb. 27, 1897.
Sir : -The very commonest and most urgent question which the
farmers ask of us is how to tell what fertilizer their land needs ; and
this is the very question which cannot be answered save by get-
ting the answer directly from the very soil and the very crop of
which the knowledge is wanted. This means that the farmer
must experiment and observe. How much good he may derive
from this experiment will depend upon how accurate he is, and
especially upon how much he knows about soils and the require-
ments of plants. In all our extension teaching, we have found
no specific need so great amongst the grown-up farmers as the
means of answering the question of how to fertilize the land. This
little paper will put the diligent farmer in the way of finding out;
and it is hopefully submitted as one of the bulletins of the Ex-
periment Station Extension, or Nixon, bill.

Plan of a set of plats upon which the farmer may ask the soil and the plant
what fertilizers are needed :

I S plat.

2 K plat. 20 lbs. muriate of potash.

3 N plat. 20 lbs. nitrate of soda, or 40 lbs. tankage or dried blood.

K N plalt i 20 lbs. muriate of p tash, o 20 lbs. muriate of potash,
S20 lbs. nitrate of soda; 40 lbs. tankage, etc.

5 0 plat. No fertilizer.

6 P plat. 5 40 lbs. plain superphosphate with
1 5 %o phosphoric acid.

7 K P Plat. 20 lbs. muriate of potash,
7 40 lbs. superphosphate.
f20 lbs. nitrate of soda, f40 lbs. tankage, etc.,
8 N K P plat. 20 lbs. muriate of potash, or 20 lbs. muriate of potash,
40 lbs. superphosphate; 40 lbs. superphosphate.
NP plat 20 lbs. nitrate of soda, o 40 lbs. tankage, etc.,
9 N pl. 40 lbs. superphosphate;r I 40 lbs. superphosphate.

Size of plats I-io acre. Upon each plat the same crop is to be grown, care
being taken that the seed is pure and that each plat receives exactly the same
amount of seed.
(S, stable manure; K, potash; N, nitrogen; P, phosphoric acid; 0, no


Water and its constituents hydrogen and oxygen, and carbon,
nitrogen, phosphoric acid, potash and lime are the chief compo-
nents of every crop that the farmer or the horticulturist produces.
If the quantity that the crop can get of any one of them is too
small for the making of a good yield, the yield will not be suf-
ficient no matter how much there may be of all the others. If the
quantity of any one of them is more than enough for a good yield,
it is only foolishness to supply any more of that substance in fer-
tilizers. The supply of water and its constituents, and of carbon,
are practically beyond the control of the crop-grower except in so
far as water may here and there be supplied by irrigation, or
may everywhere be conserved by shallow surface tillage properly
managed. The supply of lime is usually large enough in ordinary
arable soils. Therefore only nitrogen, phosphoric acid and potash
are left to be looked after ; these, as every consumer of commercial
fertilizers knows, are the things that he pays for in whatever of
these fertilizers he buys.
By the introduction of leguminousplants, such as clover, vetch,
lupine, peas, beans and the like, into his rotations, he may save
himself from the necessity of buying so much nitrogen as he might
otherwise have to get in order to preserve the proper balance of
the plant-foods in his soils. These crops, as almost every farmer
knows, can get a part of their nitrogen from the air; and they will
in general get more of it from the air and less from the soil the
poorer the soil is in available nitrogen, and the richer it is within
certain limits in potash and phosphoric acid.
Every ordinary arable soil has far more than enough of nitro-
gen, phosphoric acid and potash for the production of a good
many crops; and yet there are many such soils which will not
yield paying crops unless fertilized with one or more of these very
same plant-foods.
It may be taken for granted that an acre of every such soil con-
tains in the uppermost twelve inches at least 5,600 lbs. of nitro-


gen, 5,000 of potash and 3,800 of phosphoric acid. These quan-
tities are from 50 to 500 times greater than those sold off the farm
in any crop. There is at least 50 times as much nitrogen in such
a soil as is sold in any part of any crop, and much oftener Ioo or
even 200 times as much. There is at least ioo times as much
potash as is carried off the farm in any part of a crop sold, and
oftener 500 times as much. Similar figures might be given for
phosphoric acid. Why, then, must we fertilize our soils, in one
way or another?
The one most important reason is that these plant-foods in the
soil are for the most part in an insoluble, or as very commonly
said, unavailable form, and that they usually become available
only little by little each year. That they do thus become gradu-
ally available, is clearly shown by some of the experiments of
Lawes and Gilbert, of England; some of their plats have yielded
crops of wheat and other cereals now for fifty years and more,
without any manure.
It may be, however, that one of these, foods does become avail-
able year by year in large enough quantities to contribute its
share towards a good yield of some crop, provided that there is
enough of the other two, but that there is in fact not enough of
the other two ; or it may be that enough of two of the foods will
become available fast enough each season fora good crop, but that
the other one will not; there will be only a poor crop in either
There are cases in which it would be only folly, with some thou-
sands of pounds of the one or the two foods in the soil, and in
such a condition that the crop grown on it can get all it needs for
a good yield, (at least for one year, and probably for the next year,
and even for a few years more), to buy these foods in commercial
manure; nor would it be the height of wisdom to keep putting
them on the soil year after year in stable manure, since that also
contains the three foods under consideration, as well as other use-
ful substances.
There are therefore two ways of using manures of any kind,
stable or commercial. One may he called the blind and unbusi-
ness-like way, the other the sharp and business-like way. We
will consider only the second way.


The man who follows this second way, realizes that it may not be
necessary to supply every crop on every soil with all three of the
plant-foods mentioned above. He knows that different crops,
while needing all these foods do not need the same quantities of
all of them; he may suppose that this soil or that soil on
his farm will yield an ample supply of one or two of these foods
for as big a crop of some one kind as he wants to get, and he
realizes that it may be profitable for him to find out what the real
state of the case is.
The only way to get this information is the way by which
pretty much all that we know about agriculture has been learned-
by experiment. The crops that it is most profitable for him to raise
must be fed, on the soil upon which he wants to raise them, with
these three plant-foods, one by one, and with mixtures of them in
the four combinations only that are possible. This is no easy
road to learning; but for an intelligent farmer who has any dis-
position at all to study his business it will be pleasant work, and
will put some variety into his otherwise too monotonous occupa-
I propose, then, to give full and simple directions for making
these experiments in as reliable a manner as possible, and with
the least possible expense and labor.
The selection of the field.-The field should be as uniform in
character throughout as possible, and should have borne the same
crop all over, at least in the preceding year, and should have been
manured alike all over for that crop. If the field has been pretty
well exhausted by a three or four-year rotation, more decisive re-
sults will probably be obtained than if it is in good condition.
If not level or nearly so the slope should be as uniform as prac-
ticable. The underdrainage should be at least fairly efficient and
uniform. The field upon which it may be most desired to make
the experiment may not meet all these requirements; but it is
probable that a fair approach to it can be made in most parts of
this state.
The size, shape and arrangement of the plats.-The size should
depend on the uniformity of the soil; for a very large field, and
not fairly alike in the character of the soil and previous manuring


and cropping, larger plats would be advisable than for a smaller
field of even character. The size of the plat must be determined
also by the kind of crop that is to be experimented with. For a
vineyard it should be larger than for corn; and for corn larger
than for wheat or any similar sowed crop.
Long and narrow plats are generally considered as better than
square ones, or broad and short ones. One advantage gained by
long and narrow plats is that if there is unlikeness in strips across
the field, all the plats can be laid out so as to run across those
unlike strips; all the plats will then gain or lose alike.
The best arrangement, then, is to have plats as narrow as they
can be and still carry a reasonable number of rows of the crop,
and, unless the field is too large, extending from one side to the
other, and across all unlike strips. Such an arrangement would
reduce the labor of planting and tillage to a minimum, besides
securing the probable advantage of greater evenness in results.
SA set of plats seventeen and one-half feet wide would carry
five rows of corn or potatoes, with three and one-half feet
between the rows; there would then be three rows to harvest for
the measurement of the crop, the two outside rows being rejected.
For cereals, as wheat, rye, barley and oats, plats as wide as could
be sown with the drill, with two or three feet vacant spaces
between the plats, would answer. For small fruits, plats carry-
ing three rows should be taken, the fruit of the inner row only
being harvested for the measurement of the crop.
The fertilizers.-For phosphoric acid use what is called plain
superphosphate. Dissolved bone black comes nearest to this of
any fertilizer in the market. One responsible firm guarantees its
dissolved bone black to contain sixteen to eighteen per cent of
available phosphoric acid.
For potash use the high-grade muriate, which is always of good
quality when obtained from reputable dealers. Only in excep-
tional cases would it be better to use the more expensive sulfate.
For nitrogen, wherever the fertilizer can be applied as a top
dressing on the growing crop in early spring and again in early
summer, use nitrate of soda, the cheapest nitrogen fertilizer on the
market. But if for any reason it is impracticable to apply the
nitrogen in this manner, use fine ground tankage or dried and


ground blood and meat; the former is a little cheaper. Either of
them can be mixed with the phosphate and the potash and applied
at the time when the seed is put in the ground, or earlier.
The quantity of the fertilizer to be applied.-A liberal dressing
will be more likely to give a decisive answer to the question put
by the experiment than a scanty dressing will. I would recom-
mend the following quantities per acre : of nitrate of soda, 400
pounds, or of tankage or dried blood used instead of nitrate of soda,
6oo pounds; of plain superphosphate, 800 pounds; of muriate
of potash, 800 pounds. The fertilizers should be dry and finely
powdered, and if applied together should be first very thoroughly
The cultivation of all the plots of the same set should be as nearly
alike as possible. Therefore the whole of that portion of the field
selected for any one set of experiments should be plowed and other-
wise prepared for fertilizing and seeding on the same day ; all the
fertilizer that is to be applied and the seed should be put
in on the same day. If nitrate is to be used as a top dressing
it should be applied on all the plots of a set on the same day
E ach cultivating or hoeing of the plots of one set should be done.
and the crop of all the plots of a set should be harvested, on the
same day. As soon as practicable after every rain, every plat
should be surface stirred to the depth of two or three inches, in
order to conserve the moisture.
All these directions being followed, differences between the
yields of different plats, due to any other causes than differences
in the fertilizing, will be reduced to a minimum, and the results
due to differences in fertilizing will be likely to come out more
The number of plats for one complete set of experiments and
the manner of fertilizing them is shown in the diagram at the
beginning of this bulletin; the size of the plat is supposed to be
one-tenth of an acre. The abbreviations used are K for potash,
P for phosphoric acid, N for nitrogen, O for no fertilizer, and
S for stable manure, if it is desired to have a plat so ferti-
lized in order to show whether there is profit in using any com-
bination of commercial manures instead of the home .made product.
For the sake of economy in cost of fertilizers and labor, the

146 BULLETIN 129.

size of the plats can be reduced to one-twentieth of an acre; if
the field is fairly uniform in character, the results with smaller
plats might be just as reliable as those with larger plats. Of
course only half as much of each fertilizer will be required on
plats half as large as those indicated in the diagram.
The growing crops should be looked over from time to time,
and a record should be kept of any differences observed between
the different plats, of attacks of insect pests or of fungous dis-
eases. A record of the weather should be kept.
The harvesting of the crop.- In carrying out this part of the
work, allowance must be made for the possible growth of the roots
of one row into the feeding-ground of the adjoining rows; thus
the outside row of one plat may steal food from the next plat that
was not intended for it ; hence the directions to exclude the two
outside rows of each plat, one on one side and the other on the
other side, and not to include the crop of those rows in the har-
vest measured, are important. Since this cannot be done conven-
iently with wheat and other small grains, it is recommended to
leave vacant spaces of two feet between the plats.
In measuring the crop, due credit should be given for every
part of it that can be utilized in any way ; if corn, not only the
seed, but the stalks ; if wheat, oats, etc., the straw as well as the
seed ; if potatoes, of course only the tubers.
The results.-In spite of all the care that may be taken in car-
rying out these soil tests, irregularities will appear in the results,
sometimes so great that it is not easy to decide what their real
meaning is; weather, soil, tillage and fertilizer work together
for the making of the crop on each of the plats. All the plats
suffer alike in bad weather and rejoice alike in good weather; the
tillage has been the same for all the plats; all the plats were
planted on the same day; only the fertilizing is different, because
we made it so. The soil we suppose to be at least fairly uniform
throughout; if, however, it does differ seriously from end to end
of the field, all our long and narrow plats run across these irregu-
larities and should be affected alike by them.
There may, however, be differences not easy to detect in the
soil of different plats, by which the growth on one plat may be
specially favored, or by means of which the fertilizer may be bet-


ter utilized. Whatever the reasons may be they will tell upon
the results but will make less trouble for us the more careful we
are as to everything that we can control.
It is possible by a careful study of the results to correct some of
the discrepancies. A few years ago a German agricultural chem-
ist proposed a method for making such corrections by which the
results could be evened up and made to show much more clearly
what the soil and crop experimented upon require in the way of
plant-food. The explanation of this method could not be made
clear without illustrations, and such illustrations would be
more interesting if drawn from actual experiments carried out in
this country.
The writer of this paper will be glad to correspond with any
farmers or horticulturists of this state who are disposed to try this
method of field experiments, and answer any questions about the
matter, go over the results obtained, apply the corrections accord-
ing to the method above mentioned, and finally to issue in
another bulletin early next year an account of all the experiments
reported to him. G. C. CALDWELL.

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