EXPERIMENTS ON CLOVER-SOILS FROM BURCOTT LODGE FARM, LEIGHTON BUZZARD.
“The soils for the next experiments, were kindly supplied to me, in
1866, by Robert Valentine, of Burcott Lodge, who also sent me some notes
respecting the growth and yield of clover-hay and seed on this soil.
“Foreign seed, at the rate of 12 lbs. per acre, was sown with a crop of
wheat, which yielded five quarters per acre the previous year.
“The first crop of clover was cut down on the 25th of June, 1866, and
carried on June 30th. The weather was very warm, from the time of
cutting until the clover was carted, the thermometer standing at 80
Fahr. every day. The clover was turned in the swath, on the second day
after it was cut; on the fourth day, it was turned over and put into
small heaps of about 10 lbs. each; and on the fifth day, these were
collected into larger cocks, and then stacked.
“The best part of an 11-acre field, produced nearly three tons of
clover-hay, sun-dried, per acre; the whole field yielding on an average,
2½ tons per acre. This result was obtained by weighing the stack three
months after the clover was carted. The second crop was cut on the 21st
of August, and carried on the 27th, the weight being nearly 30 cwt. of
hay per acre. Thus the two cuttings produced just about four tons of
clover-hay per acre.
“The 11 acres were divided into two parts. About one-half was mown for
hay a second time, and the other part left for seed. The produce of the
second half of the 11-acre field, was cut on the 8th of October, and
carried on the 10th. It yielded in round numbers, 3 cwt. of clover-seed
per acre, the season being very unfavorable for clover-seed. The second
crop of clover, mown for hay, was rather too ripe, and just beginning to
show seed.
“A square foot of soil, 18 inches deep, was dug from the second portion
of the land which produced the clover-hay and clover-seed.
SOIL FROM PART OF 11-ACRE FIELD TWICE MOWN FOR HAY.
“The upper six inches of soil, one foot square, contained all the main
roots of 18 strong plants; the next six inches, only small root fibres,
and in the third section, a six-inch slice cut down at a depth of 12
inches from the surface, no distinct fibres could be found. The soil was
almost completely saturated with rain when it was dug up on the 13th of
September, 1866:
Lbs.
The upper six inches of soil, one foot square, weighed 60
The second ” ” ” 61
The third ” ” ” 63
“These three portions of one foot of soil, 18 inches deep, were dried
nearly completely, and weighed again; when the first six inches weighed
51¼ lbs.; the second six inches, 51 lbs. 5 oz.; and the third section,
54 lbs. 2 oz.
“The first six inches contained 3 lbs. of silicious stones, (flints),
which were rejected in preparing a sample for analysis; in the two
remaining sections there were no large sized stones. The soils were
pounded down, and passed through a wire sieve.
“The three layers of soil, dried and reduced to powder, were mixed
together, and a prepared average sample, when submitted to analysis,
yielded the following results:
Composition of Clover-Soil, 18 Inches Deep, From Part of 11-Acre
Field, Twice Mown for Hay.
{Organic matter 5.86
{Oxides of iron 6.83
{Alumina 7.12
{Carbonate of lime 2.13
Soluble in {Magnesia 2.01
hydrochloric acid. {Potash .67
{Soda .08
{Chloride of sodium .02
{Phosphoric acid .18
{Sulphuric acid .17
{Insoluble silicious matter, 74.61.
{ Consisting of:
{Alumina 4.37
{Lime, (in a state of silicate) 4.07
Insoluble in acid {Magnesia .46
{Potash .19
{Soda .23
{Silica 65.29
-----
99.68
=====
“This soil, it will be seen, contained, in appreciable quantities, not
only potash and phosphoric acid, but all the elements of fertility which
enter into the composition of good arable land. It may be briefly
described as a stiff clay soil, containing a sufficiency of lime,
potash, and phosphoric acid, to meet all the requirements of the
clover-crop. Originally, rather unproductive, it has been much, improved
by deep culture; by being smashed up into rough clods, early in autumn,
and by being exposed in this state to the crumbling effects of the air,
it now yields good corn and forage crops.
“In separate portions of the three layers of soil, the proportions of
nitrogen and phosphoric acid contained in each layer of six inches, were
determined and found to be as follows:
Soil dried at 212 deg. Fahr.
1st six 2d six 3d six
inches. inches. inches.
Percentage of phosphoric acid .249 .134 .172
Nitrogen 1.62 .092 .064
Equal to ammonia .198 .112 .078
“In the upper six inches, as will be seen, the percentage of both
phosphoric acid and nitrogen, was larger than in the two following
layers, while the proportion of nitrogen in the six inches of surface
soil, was much larger than in the next six inches; and in the third
section, containing no visible particles of root-fibres, only very
little nitrogen occurred.
“In their natural state, the three layers of soil contained:
1st six 2d six 3d six
inches. inches. inches.
Moisture 17.16 18.24 16.62
Phosphoric acid .198 .109 .143
Nitrogen .134 .075 .053
Equal to ammonia .162 .091 .064
Lbs. Lbs. Lbs.
Weight of one foot square of soil 60 61 63
“Calculated per acre, the absolute weight of one acre of this land, six
inches deep, weighs:
Lbs.
1st six inches 2,613,600
2d six inches 2,657,160
3d six inches 2,746,280
=========
“No great error, therefore, will be made, if we assume in the subsequent
calculations, that six inches of this soil weighs two and one-half
millions of pounds per acre.
“An acre of land, according to the preceding determinations, contains:
1st six 2d six 3d six
inches, inches, inches,
Lbs. Lbs. Lbs.
Phosphoric acid 4,950 2,725 3,575
Nitrogen 3,350 1,875 1,325
Equal to ammonia 4,050 2,275 1,600
===== ===== =====
“The proportion of phosphoric acid in six inches of surface soil, it
will be seen, amounted to about two-tenths per cent; a proportion of the
whole soil, so small that it may appear insufficient for the production
of a good corn-crop. However, when calculated to the acre, we find that
six inches of surface soil in an acre of land, actually contain over two
tons of phosphoric acid. An average crop of wheat, assumed to be 25
bushels of grain, at 60 lbs. per bushel, and 3,000 lbs. of straw,
removes from the land on which it is grown, 20 lbs. of phosphoric acid.
The clover-soil analyzed by me, consequently contains an amount of
phosphoric acid in a depth of only six inches, which is equal to that
present in 247½ average crops of wheat; or supposing that, by good
cultivation and in favorable seasons, the average yield of wheat could
be doubled, and 50 bushels of grain, at 60 lbs. a bushel, and 6,000 lbs.
of straw could be raised, 124 of such heavy wheat-crops would contain no
more phosphoric acid than actually occurred in six inches of this
clover-soil per acre.
“The mere presence of such an amount of phosphoric acid in a soil,
however, by no means proves its sufficiency for the production of so
many crops of wheat; for, in the first place, it can not be shown that
the whole of the phosphoric acid found by analysis, occurs in the soil
in a readily available combination; and, in the second place, it is
quite certain that the root-fibres of the wheat-plant can not reach and
pick up, so to speak, every particle of phosphoric acid, even supposing
it to occur in the soil in a form most conducive to ‘ready assimilation
by the plant.’
“The calculation is not given in proof of a conclusion which would be
manifestly absurd, but simply as an illustration of the enormous
quantity in an acre of soil six inches deep, of a constituent forming
the smaller proportions of the whole weight of an acre of soil of that
limited depth. It shows the existence of a practically unlimited amount
of the most important mineral constituents of plants, and clearly points
out the propriety of rendering available to plants, the natural
resources of the soil in plant-food; to draw, in fact, up the mineral
wealth of the soil, by thoroughly working the land, and not leaving it
unutilized as so much dead capital.”
“Good,” said the Deacon, “that is the right doctrine.”
“The roots,” continues Dr. Vœlcker, “from one square foot of soil were
cleaned as much as possible, dried completely at 212°, and in that state
weighed 240 grains. An acre consequently contained 1,493½ lbs. of dried
clover-roots.
“The clover-roots contained, dried at 212° Fahr.,
Organic matter* 81.33
Mineral matter,† (ash) 18.67
------
100.00
======
* Yielding nitrogen 1.635
Equal to ammonia 1.985
† Including insoluble silicious
matter, (clay and sand) 11.67
“Accordingly the clover-roots in an acre of land furnished 24½ lbs. of
nitrogen. We have thus:
Lbs. of
nitrogen
In the six inches of surface soil 3,350
In large clover-roots 24½
In second six inches of soil 1,875
---------
Total amount of nitrogen in one acre of
soil 12 inches deep 5,249½
Equal to ammonia 6,374½
=========
Or in round numbers, two tons six cwt. of nitrogen per acre; an enormous
quantity, which must have a powerful influence in encouraging the
luxuriant development of the succeeding wheat-crop, although only a
fraction of the total amount of nitrogen in the clover remains may
become sufficiently decomposed in time to be available to the young
wheat-plants.
CLOVER-SOIL FROM PART OF 11-ACRE FIELD OF BURCOTT LODGE FARM, LEIGHTON
BUZZARD, ONCE MOWN FOR HAY, AND LEFT AFTERWARDS FOR SEED.
“Produce 2½ tons of clover-hay, and 3 cwt. of seed per acre.
“This soil was obtained within a distance of five yards from the part of
the field where the soil was dug up after the two cuttings of hay. After
the seed there was some difficulty in finding a square foot containing
the same number of large clover-roots, as that on the field twice mown;
however, at last, in the beginning of November, a square foot containing
exactly 18 strong roots, was found and dug up to a depth of 18 inches.
The soil dug after the seed was much drier than that dug after the two
cuttings of hay:
The upper six inches deep, one foot square, weighed 56 lbs.
The next ” ” ” 58 ”
The third ” ” ” 60 ”
=======
“After drying by exposure to hot air, the three layers of soil weighed:
The upper six inches, one foot square 49¾ lbs.
The next ” ” 50½ ”
The third ” ” 51¼ ”
===========
“Equal portions of the dried soil from each six-inch section were mixed
together and reduced to a fine powder. An average sample thus prepared,
on analysis, was found to have the following composition:
Composition of Clover-Soil Once Mown for Hay, and Afterwards Left for
Seed. Dried at 212° Fahr.
{ Organic matter 5.34
{ Oxides of iron 6.07
{ Alumina 4.51
{ Carbonate of lime 7.51
Soluble in { Magnesia 1.27
hydrochloric Acid { Potash .52
{ Soda .16
{ Chloride of sodium .03
{ Phosphoric acid .15
{ Sulphuric acid .19
{ Insoluble silicious matter,
{ 73.84. Consisting of:
{ Alumina 4.14
{ Lime (in a state of silicate) 2.69
Insoluble in acid { Magnesia .68
{ Potash .24
{ Soda .21
{ Silica 65.88
-----
99.59
=====
“The soil, it will be seen, in general character, resembles the
preceding sample; it contains a good deal of potash and phosphoric
acid, and may be presumed to be well suited to the growth of clover. It
contains more carbonate of lime, and is somewhat lighter than the sample
from the part of the field twice mown for hay, and may be termed heavy
calcareous clay.
“An acre of this land, 18 inches deep, weighed, when very nearly dry:
Lbs.
Surface, six inches 2,407,900
Next ” 2,444,200
Third ” 2,480,500
“Or in round numbers, every six inches of soil weighed per acre 2½
millions of pounds, which agrees tolerably well with the actual weight
per acre of the preceding soil.
“The amount of phosphoric acid and nitrogen in each six-inch layer was
determined separately, as before, when the following results were
obtained:
In Dried Soil.
First six Second Third six
inches. six inches. inches.
Percentage of phosphoric acid .159 .166 .140
Nitrogen .189 .134 .089
Equal to ammonia .229 .162 .108
“An acre, according to these determinations, contains in the three
separate sections:
First six Second Third six
inches. six inches. inches.
lbs. lbs. lbs.
Phosphoric acid 3,975 4,150 3,500
Nitrogen 4,725 3,350 2,225
Equal to ammonia 5,725 4,050 2,700
“Here, again, as might naturally be expected, the proportion of nitrogen
is largest in the surface, where all the decaying leaves dropped during
the growth of the clover for seed are found, and wherein root-fibres are
more abundant than in the lower strata. The first six inches of soil, it
will be seen, contained in round numbers, 2½ tons of nitrogen per acre,
that is, considerably more than was found in the same section of the
soil where the clover was mown twice for hay; showing plainly, that
during the ripening of the clover seed, the surface is much enriched by
the nitrogenous matter in the dropping leaves of the clover-plant.
“_Clover-roots_.--The roots from one square foot of this soil, freed as
much as possible from adhering soil, were dried at 212°, and when
weighed and reduced to a fine powder, gave, on analysis, the following
results:
Organic matter* 64.76
Mineral matter† 35.24
-------
100.00
=======
* Containing nitrogen 1.702
Equal to ammonia 2.066
† Including clay and sand
(insoluble silicious matter) 26.04
“A square foot of this soil produced 582 grains of dried clover-roots,
consequently an acre yielded 3,622 lbs. of roots, or more than twice the
weight of roots obtained from the soil of the same field where the
clover was twice mown for hay.
“In round numbers, the 3,622 lbs. of clover-roots from the land mown
once, and afterwards left for seed, contained 51½ lbs. of nitrogen.
“The roots from the soil after clover-seed, it will be noticed, were not
so clean as the preceding sample, nevertheless, they yielded more
nitrogen. In 64.76 of organic matter, we have here 1.702 of nitrogen,
whereas, in the case of the roots from the part of the field where the
clover was twice mown for hay, we have in 81.33 parts, that is, much
more organic matter, and 1.635, or rather less of nitrogen. It is
evident, therefore, that the organic matter in the soil after
clover-seed, occurs in a more advanced stage of decomposition, than
found in the clover-roots from the part of the field twice mown. In the
manure, in which the decay of such and similar organic remains proceeds,
much of the non-nitrogenous, or carbonaceous matters, of which these
remains chiefly, though not entirely, consist, is transformed into
gaseous carbonic acid, and what remains behind, becomes richer in
nitrogen and mineral matters. A parallel case, showing the dissipation
of carbonaceous matter, and the increase in the percentage of nitrogen
and mineral matter in what is left behind, is presented to us in fresh
and rotten dung; in long or fresh dung, the percentage of organic
matter, consisting chiefly of very imperfectly decomposed straw, being
larger, and that of nitrogen and mineral matter smaller, than in
well-rotted dung.
“The roots from the field after clover-seed, it will be borne in mind,
were dug up in November, whilst those obtained from the land twice mown,
were dug up in September; the former, therefore, may be expected to be
in a more advanced state of decay than the latter, and richer in
nitrogen.
“In an acre of soil, after clover-seed, we have:
Lbs.
Nitrogen in first six inches of soil 4,725
Nitrogen in roots 51½
Nitrogen in second six inches of soil 3,350
-------
Total amount of nitrogen, per acre, in
twelve inches of soil 8,126½
=======
“Equal to ammonia, 9,867 lbs.: or, in round numbers, 3 tons and 12½
cwts. of nitrogen per acre; equal to 4 tons 8 cwts. of ammonia.
“This is a very much larger amount of nitrogen than occurred in the
other soil, and shows plainly that the total amount of nitrogen
accumulates especially in the surface-soil, when clover is grown for
seed; thus explaining intelligibly, as it appears to me, why wheat, as
stated by many practical men, succeeds better on land where clover is
grown for seed, than where it is mown for hay.
“All the three layers of the soil, after clover-seed, are richer in
nitrogen than the same sections of the soil where the clover was twice
mown, as will be seen by the following comparative statement of results:
--------------+--------------------------+--------------------------
| I. | II.
| Clover-Soil twice | Clover-Soil once mown
| mown. | and then left for seed.
+--------+--------+--------+--------+--------+--------
| | | | | |
| Upper | Second | Third | Upper | Next | Lowest
|6 inches|6 inches|6 inches|6 inches|6 inches|6 inches
--------------+--------+--------+--------+--------+--------+--------
Percentage of | | | | | |
nitrogen in | .168 | .092 | .064 | .189 | .134 | .089
dried soil | | | | | |
Equal to | | | | | |
ammonia | .198 | .112 | .078 | .229 | .162 | .108
--------------+--------+--------+--------+--------+--------+--------
“This difference in the amount of accumulated nitrogen in clover-land,
appears still more strikingly on comparing the total amounts of nitrogen
per acre in the different sections of the two portions of the 11-acre
field.
Percentage of Nitrogen Per Acre.
First six Second Third six
inches. six inches. inches.
Lbs. Lbs. Lbs.
I. In soil, clover twice }
mown* } 3,350 1,875 1,325
II. In soil, clover once }
mown and seeded }
afterwards† } 4,725 3,350 2,225
===== ===== =====
Equal to ammonia:
* I. Clover twice mown } 4,050 2,275 1,600
† II. Clover seeded } 5,725 4,050 2,700
Lbs.
I. Nitrogen in roots of clover twice mown } 24½
II. Nitrogen in clover, once mown, and grown }
for seed afterwards } 51½
I. Weight of dry roots per acre from Soil I } 1,493½
II. Weight of dry roots per acre from Soil II } 3,622
Total amount of nitrogen in 1 acre, 12 inches }
deep of Soil I* } 5,249¼
Total amount of nitrogen in 1 acre, 12 inches }
deep of Soil II† } 8,126¼
Excess of nitrogen in an acre of soil 12 }
inches deep, calculated as ammonia in part }
of field, mown once and then seeded } 3,592½
---------
* Equal to ammonia } 6,374½
† Equal to ammonia } 9,867
“It will be seen that not only was the amount of large clover-roots
greater in the part where clover was grown for seed, but that likewise
the different layers of soil were in every instance richer in nitrogen
after clover-seed, than after clover mown twice for hay.
“Reasons are given in the beginning of this paper which it is hoped will
have convinced the reader, that the fertility of land is not so much
measured by the amount of ash constituents of plants which it contains,
as by the amount of nitrogen, which, together with an excess of such ash
constituents, it contains in an available form. It has been shown
likewise, that the removal from the soil of a large amount of mineral
matter in a good clover-crop, in conformity with many direct field
experiments, is not likely in any degree to affect the wheat-crop, and
that the yield of wheat on soils under ordinary cultivation, according
to the experience of many farmers, and the direct and numerous
experiments of Messrs. Lawes and Gilbert, rises or falls, other
circumstances being equal, with the supply of available nitrogenous food
which is given to the wheat. This being the case, we can not doubt that
the benefits arising from the growth of clover to the succeeding wheat,
are mainly due to the fact that an immense amount of nitrogenous food
accumulates in the soil during the growth of clover.
“This accumulation of nitrogenous plant-food, specially useful to cereal
crops, is, as shown in the preceding experiments, much greater when
clover is grown for seed, than when it is made into hay. This affords an
intelligible explanation of a fact long observed by good practical men,
although denied by others who decline to accept their experience as
resting upon trustworthy evidence, because, as they say, land cannot
become more fertile when a crop is grown upon it for seed, which is
carried off, than when that crop is cut down and the produce consumed on
the land. The chemical points brought forward in the course of this
inquiry, show plainly that mere speculation as to what can take place in
a soil, and what not, do not much advance the true theory of certain
agricultural practices. It is only by carefully investigating subjects
like the one under consideration, that positive proofs are given,
showing the correctness of intelligent observers in the fields. Many
years ago, I made a great many experiments relative to the chemistry of
farm-yard manure, and then showed, amongst other particulars, that
manure, spread at once on the land, need not there and then be plowed
in, inasmuch as neither a broiling sun, nor a sweeping and drying wind
will cause the slightest loss of ammonia; and that, therefore, the
old-fashioned farmer who carts his manure on the land as soon as he can,
and spreads it at once, but who plows it in at his convenience, acts in
perfect accordance with correct chemical principles involved in the
management of farm-yard manure. On the present occasion, my main object
has been to show, not merely by reasoning on the subject, but by actual
experiments, that the larger the amounts of nitrogen, potash, soda,
lime, phosphoric acid, etc., which are removed from the land in a
clover-crop, the better it is, nevertheless, made thereby for producing
in the succeeding year an abundant crop of wheat, other circumstances
being favorable to its growth.
“Indeed, no kind of manure can be compared in point of efficacy for
wheat, to the manuring which the land gets in a really good crop of
clover. The farmer who wishes to derive the full benefit from his
clover-lay, should plow it up for wheat as soon as possible in the
autumn, and leave it in a rough state as long as is admissible, in order
that the air may find free access into the land, and the organic remains
left in so much abundance in a good crop of clover be changed into
plant-food; more especially, in other words, in order that the crude
nitrogenous organic matter in the clover-roots and decaying leaves, may
have time to become transformed into ammoniacal compounds, and these, in
the course of time, into nitrates, which I am strongly inclined to think
is the form in which nitrogen is assimilated, par excellence by cereal
crops, and in which, at all events, it is more efficacious than in any
other state of combination wherein it may be used as a fertilizer.
“When the clover-lay is plowed up early, the decay of the clover is
sufficiently advanced by the time the young wheat-plant stands in need
of readily available nitrogenous food, and this being uniformly
distributed through the whole of the cultivated soil, is ready to
benefit every single plant. This equal and abundant distribution of
food, peculiarly valuable to cereals, is a great advantage, and speaks
strongly in favor of clover as a preparatory crop for wheat.
“Nitrate of soda, an excellent spring top-dressing for wheat and cereals
in general, in some seasons fails to produce as good an effect as in
others. In very dry springs, the rainfall is not sufficient to wash it
properly into the soil and to distribute it equally, and in very wet
seasons it is apt to be washed either into the drains or into a stratum
of the soil not accessible to the roots of the young wheat. As,
therefore, the character of the approaching season can not usually be
predicted, the application of nitrate of soda to wheat is always
attended with more or less uncertainty.
“The case is different, when a good crop of clover-hay has been obtained
from the land on which wheat is intended to be grown afterwards. An
enormous quantity of nitrogenous organic matter, as we have seen, is
left in the land after the removal of the clover-crop; and these remains
gradually decay and furnish ammonia, which at first and during the
colder months of the year, is retained by the well known absorbing
properties which all good wheat-soils possess. In spring, when warmer
weather sets in, and the wheat begins to make a push, these ammonia
compounds in the soil are by degrees oxidized into nitrates; and as this
change into food peculiarly favorable to young cereal plants, proceeds
slowly but steadily, we have in the soil itself, after clover, a source
from which nitrates are continuously produced; so that it does not much
affect the final yield of wheat, whether heavy rains remove some or all
of the nitrate present in the soil. The clover remains thus afford a
more continuous source from which nitrates are produced, and greater
certainty for a good crop of wheat than when recourse is had to
nitrogenous top-dressings in the spring.
SUMMARY.
“The following are some of the chief points of interest which I have
endeavored fully to develope in the preceding pages:
“1. A good crop of clover removes from the soil more potash, phosphoric
acid, lime, and other mineral matters, which enter into the composition
of the ashes of our cultivated crops, than any other crop usually grown
in this country.
“2. There is fully three times as much nitrogen in a crop of clover as
in the average produce of the grain and straw of wheat per acre.
“3. Notwithstanding the large amount of nitrogenous matter and of
ash-constituents of plants, in the produce of an acre, clover is an
excellent preparatory crop for wheat.
“4. During the growth of clover, a large amount of nitrogenous matter
accumulates in the soil.
“5. This accumulation, which is greatest in the surface soil, is due to
decaying leaves dropped during the growth of clover, and to an abundance
of roots, containing, when dry, from one and three-fourths to two per
cent of nitrogen.
“6. The clover-roots are stronger and more numerous, and more leaves
fall on the ground when clover is grown for seed, than when it is mown
for hay; in consequence, more nitrogen is left after clover-seed, than
after hay, which accounts for wheat yielding a better crop after
clover-seed than after hay.
“7. The development of roots being checked, when the produce, in a green
condition, is fed off by sheep, in all probability, leaves still less
nitrogenous matter in the soil than when clover is allowed to get riper
and is mown for hay; thus, no doubt, accounting for the observation made
by practical men, that, notwithstanding the return of the produce in the
sheep excrements, wheat is generally stronger, and yields better, after
clover mown for hay, than when the clover is fed off green by sheep.
“8. The nitrogenous matters in the clover remains, on their gradual
decay, are finally transformed into nitrates, thus affording a
continuous source of food on which cereal crops specially delight to
grow.
“9. There is strong presumptive evidence that the nitrogen which exists
in the air, in shape of ammonia and nitric acid, and descends, in these
combinations, with the rain which falls on the ground, satisfies, under
ordinary circumstances, the requirements of the clover-crop. This crop
causes a large accumulation of nitrogenous matters, which are gradually
changed in the soil into nitrates. The atmosphere thus furnishes
nitrogenous food to the succeeding wheat indirectly, and, so to say,
gratis.
“10. Clover not only provides abundance of nitrogenous food, but
delivers this food in a readily available form (as nitrates), more
gradually and continuously, and, consequently, with more certainty of a
good result, than such food can be applied to the land in the shape of
nitrogenous spring top-dressings.”
“Thank you Charley,” said the Doctor, “_that is the most remarkable
paper I ever listened to_. I do not quite know what to think of it. We
shall have to examine it carefully.”
“The first three propositions in the Summary,” said I, “are
unquestionably true. Proposition No. 4, is equally true, but we must be
careful what meaning we attach to the word ‘accumulate.’ The idea is,
that clover gathers up the nitrogen in the soil. It does not _increase_
the absolute amount of nitrogen. It accumulates it--brings it together.
“Proposition No. 5, will not be disputed; and I think we may accept No.
6, also, though we can not be sure that allowing clover to go to seed,
had anything to do with the increased quantity of clover-roots.
“Proposition No. 7, may or may not be true. We have no proof, only a
‘probability;’ and the same may be said in regard to propositions Nos.
8, 9, and 10.”
The Deacon seemed uneasy. He did not like these remarks. He had got the
impression, while Charley was reading, that much more was proved than
Dr. Vœlcker claims in his Summary.
“I thought,” said he, “that on the part of the field where the clover
was allowed to go to seed, Dr. Vœlcker found a great increase in the
amount of nitrogen.”
“That seems to be the general impression,” said the Doctor, “but in
point of fact, we have no proof that the growth of clover, either for
hay or for seed, had anything to do with the quantity of nitrogen and
phosphoric acid found in the soil. The _facts_ given by Dr. Vœlcker, are
exceedingly interesting. Let us look at them:
“A field of 11 acres was sown to winter-wheat, and seeded down in the
spring, with 13 lbs. per acre of clover. The wheat yielded 40 bushels
per acre. The next year, on the 25th of June, the clover was mown for
hay. We are told that ‘the _best part_ of the field yielded three tons
(6,720 lbs.) of clover-hay per acre; the whole field averaging 2½ tons
(5,600 lbs.) per acre.’
“We are not informed how much land there was of the ‘best part,’ but
assuming that it was half the field, the poorer part must have yielded
only 4,480 lbs. of hay per acre, or only two-thirds as much as the
other. This shows that there was considerable difference in the quality
or condition of the land.
“After the field was mown for hay, it was divided into two parts: one
part was mown again for hay, August 21st, and yielded about 30 cwt.
(3,360 lbs.) of hay per acre; the other half was allowed to grow six or
seven weeks longer, and was then (October 8th), cut for seed. The yield
was a little over 5½ bushels of seed per acre. Whether the clover
allowed to grow for seed, was on the richer or poorer half of the field,
we are not informed.
“Dr. Vœlcker then analyzed the soil. That from the part of the field
mown twice for hay, contained per acre:
First six Second six Third six Total, 18
inches. inches. inches. inches deep.
Phosphoric acid 4,950 2,725 3,575 11,250
Nitrogen 3,350 1,875 1,325 6,550
“The soil _from the part mown once for hay, and then for seed_,
contained per acre:
First six Second six Third six Total, 18
inches. inches. inches. inches deep.
Phosphoric acid 3,975 4,150 3,500 11,625
Nitrogen 4,725 3,350 2,225 10,300
“Dr. Vœlcker also ascertained the amount and composition of the
clover-_roots_ growing in the soil on the two parts of the field. On the
_part mown twice for hay_, the roots contained per acre 24½ lbs. of
nitrogen. On the _part mown once for hay, and then for seed_, the roots
contained 51½ lbs. of nitrogen per acre.”
“Now,” said the Doctor, “these facts are very interesting, _but there is
no sort of evidence tending to show that the clover has anything to do
with increasing or decreasing the quantity of nitrogen or phosphoric
acid found in the soil_.”
“There was more clover-roots per acre, where the clover was allowed to
go to seed. But that may be because the soil happened to be richer on
this part of the field. There was, in the first six inches of the soil,
3,350 lbs. of nitrogen per acre, on one-half of the field, and 4,725
lbs. on the other half; and it is not at all surprising that on the
latter half there should be a greater growth of clover and clover-roots.
To suppose that during the six or seven weeks while the clover was
maturing its seed, the clover-plants could accumulate 1,375 lbs. of
nitrogen, is absurd.”
“But Dr. Vœlcker,” said the Deacon, “states, and states truly, that
‘more leaves fall on the ground when clover is grown for seed, than when
it is mown for hay; and, consequently, more nitrogen is left after
clover-seed than after hay, which accounts for wheat yielding a better
crop after clover-seed than after hay.’”
“This is all true,” said the Doctor, “but we can not accept Dr.
Vœlcker’s analyses as proving it. To account in this way for the 1,375
lbs. of nitrogen, we should have to suppose that the clover-plants, in
going to seed, shed _one hundred tons_ of dry clover-leaves per acre!
The truth of the matter seems to be, that the part of the field on which
the clover was allowed to go to seed, was naturally much richer than the
other part, and consequently produced a greater growth of clover and
clover-roots.”
We can not find anything in these experiments tending to show that we
can make land rich by growing clover and selling the crop. The analyses
of the soil show that in the first eighteen inches of the surface-soil,
there was 6,550 lbs. of nitrogen per acre, on one part of the field, and
10,300 lbs. on the other part. The clover did not create this nitrogen,
or bring it from the atmosphere. The wheat with which the clover was
seeded down, yielded 40 bushels per acre. If the field had been sown to
wheat again, it probably would not have yielded over 25 bushels per
acre--and that for want of available nitrogen. And yet the clover got
nitrogen enough for over four tons of clover-hay; or as much nitrogen as
a crop of wheat of 125 bushels per acre, and 7½ tons of straw would
remove from the land.
Now what does this prove? There was, in 18 inches of the soil on the
poorest part of the field, 6,550 lbs. of nitrogen per acre. A crop of
wheat of 50 bushels per acre, and twice that weight of straw, would
require about 92 lbs. of nitrogen. But the wheat can not get this amount
from the soil, while the clover can get _double the quantity_. And the
only explanation I can give, is, that the clover-roots can take up
nitrogen from a weaker solution in the soil than wheat-roots can.
“These experiments of Dr. Vœlcker,” said I, “give me great
encouragement. Here is a soil, ‘originally rather unproductive, but much
improved by deep culture; by being smashed up into rough clods early in
autumn, and by being exposed in this state to the crumbling effects of
the air.’ It now produces 40 bushels of wheat per acre, and part of the
field yielded three tons of clover-hay, per acre, the first cutting, and
5½ bushels of clover-seed afterwards--and that in a very unfavorable
season for clover-seed.”
You will find that the farmers in England do not expect to make their
land rich, by growing clover and selling the produce. After they have
got their land rich, by good cultivation, and the liberal use of animal
and artificial manures, they may expect a good crop of wheat from the
roots of the clover. But they take good care to feed out the clover
itself on the farm, in connection with turnips and oil-cake, and thus
make rich manure.
And so it is in this country. Much as we hear about the value of clover
for manure, even those who extol it the highest do not depend upon it
alone for bringing up and maintaining the fertility of their farms. The
men who raise the largest crops and make the most money by farming, do
not sell clover-hay. They do not look to the roots of the clover for
making a poor soil rich. They are, to a man, good cultivators. They work
their land thoroughly and kill the weeds. They keep good stock, and feed
liberally, and make good manure. They use lime, ashes, and plaster, and
are glad to draw manure from the cities and villages, and muck from the
swamps, and not a few of them buy artificial manures. In the hands of
such farmers, clover is a grand renovating crop. It gathers up the
fertility of the soil, and the roots alone of a large crop, often
furnish food enough for a good crop of corn, potatoes, or wheat. But if
your land was not in good heart to start with, you would not get the
large crop of clover; and if you depend on the clover-roots alone, the
time is not far distant when your large crops of clover will be things
of the past.
AMOUNT OF ROOTS LEFT IN THE SOIL BY DIFFERENT CROPS.
“We have seen that Dr. Vœlcker made four separate determinations of the
amount of clover-roots left in the soil to the depth of six inches. It
may be well to tabulate the figures obtained:
Clover-Roots, in Six Inches of Soil, Per Acre.
------+--------------------------------+---------+---------+----------
| |Air-dry |Nitrogen |Phosphoric
| |roots, |in roots,|acid in
| |per acre.|per acre.|roots,
| | | |per acre.
------+--------------------------------+---------+---------+----------
|1st Year. | | |
No. 1.| Good Clover from brow | 7705 | 100 |
| of the hill | | |
” 2.| Bad ” ” ” | 3920 | 31 |
| ” ” ” | | |
| | | |
|2d Year. | | |
” 3.| Good Clover from bottom | 7569 | 61 | 27
| of the field | | |
” 4.| Thin ” ” brow | 8064 | 66 |
| ” ” hill | | |
| | | |
” 5.|Heavy crop of first-year clover | | |
| mown twice for hay | | 24½ |
” 6.|Heavy crop of first-year clover | | |
| mown once for hay, | | 51½ |
| and then for seed | | |
” 7.|German experiment, | | |
| 10¼ inches deep | 8921 | 191½ | 74¾
------+--------------------------------+---------+---------+----------
I have not much confidence in experiments of this kind. It is so easy to
make a little mistake; and when you take only a square foot of land, as
was the case with Nos. 5 and 6, the mistake is multiplied by 43,560.
Still, I give the table for what it is worth.
Nos. 1 and 2 are from a one-year-old crop of clover. The field was a
calcareous clay soil. It was somewhat hilly; or, perhaps, what we here,
in Western New York, should call “rolling land.” The soil on the brow of
the hill, “was very stony at a depth of four inches, so that it could
only with difficulty be excavated to six inches, when the bare
limestone-rock made its appearance.”
A square yard was selected on this shallow soil, where the clover was
good; and the roots, air-dried, weighed at the rate of 7,705 lbs. per
acre, and contained 100 lbs. of nitrogen. A few yards distance, on the
same soil, where the clover was bad, the acre of roots contained only 31
lbs. of nitrogen per acre.
So far, so good. We can well understand this result. Chemistry has
little to do with it. There was a good stand of clover on the one plot,
and a poor one on the other. And the conclusion to be drawn from it is,
that it is well worth our while to try to secure a good catch of clover.
“But, suppose,” said the Doctor, “No. 2 had happened to have been
pastured by sheep, and No. 1 allowed to go to seed, what magic there
would have been in the above figures!”
Nos. 3 and 4 are from the same field, the second year. No. 4 is from a
square yard of thin clover on the brow of the hill, and No. 3, from the
richer, deeper land towards the bottom of the hill.
There is very little difference between them. The roots of thin clover
from the brow of the hill, contain five lbs. more nitrogen per acre,
than the roots on the deeper soil.
If we can depend on the figures, we may conclude that on our poor stony
“knolls,” the clover has larger and longer roots than on the richer
parts of the field. We know that roots will run long distances and great
depths in search of food and water.
Nos. 5 and 6 are from a heavy crop of one-year-old clover. No. 5 was
mown twice for hay, producing, in the two cuttings, over four tons of
hay per acre. No. 6 was in the same field, the only difference being
that the clover, instead of being cut the second time for hay, was
allowed to stand a few weeks longer to ripen its seed. You will see that
the latter has more roots than the former.
There are 24½ lbs. of nitrogen per acre in the one case, and 51½ lbs. in
the other. How far this is due to difference in the condition of the
land, or to the difficulties in the way of getting out all the roots
from the square yard, is a matter of conjecture.
Truth to tell, I have very little confidence in any of these figures. It
will be observed that I have put at the bottom of the table, the result
of an examination made in Germany. In this case, the nitrogen in the
roots of an acre of clover, amounted to 191½ lbs. per acre. If we can
depend on the figures, we must conclude that there were nearly eight
times as much clover-roots per acre in the German field, as in the
remarkably heavy crop of clover in the English field No. 5.
“Yes,” said the Deacon, “but the one was 10¼ inches deep, and the other
only six inches deep; and besides, the German experiment includes the
‘stubble’ with the roots.”
The Deacon is right; and it will be well to give the complete table, as
published in the _American Agriculturist_:
Table Showing the Amount of Roots and Stubble Left Per Acre by
Different Crops, and the Amount of Ingredients Which They Contain
Per Acre.
-------------------------+---------------+------------+---------------
|No. of lbs. of | |
|stubble & roots| | No. of lbs.
|(dry) per acre |No. of lbs. | of ash, free
|to a depth of |of Nitrogen | from carbonic
|10¼ inches. | per acre. |acid, per acre.
-------------------------+---------------+------------+---------------
Lucern (4 years old) | 9,678.1 | 136.4 | 1,201.6
Red-Clover (1 year old,) | 8,921.6 | 191.6 | 1,919.9
Esparsette (3 years old) | 5,930.9 | 123.2 | 1,023.4
Rye | 5,264.6 | 65.3 | 1,747.8
Swedish Clover | 5,004.3 | 102.3 | 974.6
Rape | 4,477. | 56.5 | 622.3
Oats | 3,331.9 | 26.6 | 1,444.7
Lupine | 3,520.9 | 62.2 | 550.
Wheat | 3,476. | 23.5 | 1,089.8
Peas | 3,222.5 | 55.6 | 670.7
Serradella | 3,120.1 | 64.8 | 545.6
Buckwheat | 2,195.6 | 47.9 | 465.5
Barley | 1,991.4 | 22.8 | 391.1
-------------------------+---------------+------------+---------------
Contents of the Ashes, in Pounds, Per Acre.
---------------+-------+---------+-------+-------+---------+----------
| Lime. |Magnesia.|Potash.| Soda. |Sulphuric|Phosphoric
| | | | | Acid. | Acid.
---------------+-------+---------+-------+-------+---------+----------
Lucern | 197.7 | 24.2 | 36.7 | 26.4 | 18.7 | 38.5
Red-Clover | 262.9 | 48.4 | 58.3 | 20.0 | 26.1 | 74.8
Esparsette | 132.8 | 28.7 | 42.6 | 13.8 | 20.6 | 29.7
Rye | 73.2 | 14.3 | 31.2 | 43.3 | 11.8 | 24.4
Swedish Clover | 136.1 | 17.6 | 25.9 | 5.7 | 13.2 | 24.2
Rape | 163.9 | 12.9 | 34.7 | 20.9 | 30.8 | 31.9
Oats | 85.5 | 11.2 | 24.8 | 18. | 8.8 | 29.
Lupine | 80.5 | 11.2 | 16.5 | 3.5 | 7. | 13.8
Wheat | 76.7 | 10.1 | 28.4 | 11. | 7.4 | 11.8
Peas | 71.7 | 11. | 11.2 | 7. | 9.4 | 14.3
Serradella | 79.8 | 13.4 | 8.8 | 4.8 | 9. | 18.4
Buckwheat | 80. | 7.2 | 8.8 | 4.2 | 6.6 | 11.
Barley | 42.2 | 5.5 | 9.5 | 3.5 | 5.5 | 11.2
---------------+-------+---------+-------+-------+---------+----------
It may be presumed, that, while these figures are not _absolutely_, they
are _relatively_, correct. In other words, we may conclude, that
red-clover leaves more nitrogen, phosphoric acid, and potash, in the
roots and stubble per acre, than any other of the crops named.
The gross amount of dry substance in the roots, and the gross amount of
ash per acre, are considerably exaggerated, owing to the evidently large
quantity of dirt attached to the roots and stubble. For instance, the
gross amount of ash in Lucern is given as 1,201.6 lbs. per acre; while
the total amount of lime, magnesia, potash, soda, sulphuric and
phosphoric acids, is only 342.2 lbs. per acre, leaving 859.4 lbs. as
sand, clay, iron, etc. Of the 1,919.9 lbs. of ash in the acre of
clover-roots and stubble, there are 1,429.4 lbs. of sand, clay, etc. But
even after deducting this amount of impurities from a gross total of dry
matter per acre, we still have 7,492.2 lbs. of dry roots and stubble per
acre, or nearly 3¼ tons of _dry_ roots per acre. This is a very large
quantity. It is as much dry matter as is contained in 13 tons of
ordinary farm-yard, or stable-manure. And these 3¼ tons of dry
clover-roots contain 191½ lbs. of nitrogen, which is as much as is
contained in 19 tons of ordinary stable-manure. The clover-roots also
contain 74¾ lbs. of phosphoric acid per acre, or as much as is contained
in from 500 to 600 lbs. of No. 1 rectified Peruvian guano.
“But the phosphoric acid,” said the Doctor, “is not soluble in the
roots.” True, but it was soluble when the roots gathered it up out of
the soil.
“These figures,” said the Deacon, “have a very pleasant look. Those of
us who have nearly one-quarter of our land in clover every year, ought
to be making our farms very rich.”
“It would seem, at any rate,” said I, “that those of us who have good,
clean, well-drained, and well-worked land, that is now producing a good
growth of clover, may reasonably expect a fair crop of wheat, barley,
oats, corn, or potatoes, when we break it up and plow under all the
roots, which are equal to 13 or 19 tons of stable-manure per acre.
Whether we can or can not depend on these figures, one thing is clearly
proven, both by the chemist and the farmer, that a good clover-sod, on
well-worked soil, is a good preparation for corn and potatoes.”
MANURES FOR WHEAT.
Probably nine-tenths of all the wheat grown in Western New York, or the
“Genesee country,” from the time the land was first cleared until 1870,
was raised without any manure being directly applied to the land for
this crop. Tillage and clover were what the farmers depended on. There
certainly has been no systematic manuring. The manure made during the
winter, was drawn out in the spring, and plowed under for corn. Any
manure made during the summer, in the yards, was, by the best farmers,
scraped up and spread on portions of the land sown, or to be sown, with
wheat. Even so good a farmer and wheat-grower as John Johnston, rarely
used manure, (except lime, and latterly, a little guano), directly for
wheat. Clover and summer-fallowing were for many years the dependence of
the Western New York wheat-growers.
“One of the oldest and most experienced millers of Western New York,”
remarked the Doctor, “once told me that ‘ever since our farmers began to
_manure their land_, the wheat-crop had deteriorated, not only in the
yield per acre, but in the quality and quantity of the flour obtained
from it.’ It seemed a strange remark to make; but when he explained that
the farmers had given up summer-fallowing and plowing in clover, and now
sow spring crops, to be followed by winter wheat with an occasional
dressing of poor manure, it is easy to see how it may be true.”
“Yes,” said I, “it is not the _manure_ that hurts the wheat, but the
growth of spring crops and weeds that rob the soil of far more
plant-food than the poor, strawy manure can supply. We do not now,
really, furnish the wheat-crop as much manure or plant-food as we
formerly did when little or no manure was used, and when we depended on
summer-fallowing and plowing in clover.”
We must either give up the practice of sowing a spring crop, before
wheat, or we must make more and richer manure, or we must plow in more
clover. The rotation, which many of us now adopt--corn, barley,
wheat--is profitable, provided we can make our land rich enough to
produce 75 bushels of shelled corn, 50 bushels of barley, and 35 bushels
of wheat, per acre, in three years.
This can be done, but we shall either require a number of acres of rich
low land, or irrigated meadow, the produce of which will make manure for
the upland, or we shall have to purchase oil-cake, bran, malt-combs, or
refuse beans, to feed out with our straw and clover-hay, or we must
purchase artificial manures. Unless this is done, we must summer-fallow
more, on the heavier clay soils, sow less oats and barley; or we must,
on the lighter soils, raise and plow under more clover, or feed it out
on the farm, being careful to save and apply the manure.
“Better do both,” said the Doctor.
“How?” asked the Deacon.
“You had better make all the manure you can,” continued the Doctor, “and
buy artificial manures besides.”
“The Doctor is right,” said I, “and in point of fact, our best farmers
are doing this very thing. They are making more manure and buying more
manure than ever before; or, to state the matter correctly, they are
buying artificial manures; and these increase the crops, and the extra
quantity of straw, corn, and clover, so obtained, enables them to make
more manure. They get cheated sometimes in their purchases; but, on the
whole, the movement is a good one, and will result in a higher and
better system of farming.”
I am amused at the interest and enthusiasm manifested by some of our
farmers who have used artificial manures for a year or two. They seem to
regard me as a sad old fogy, because I am now depending almost entirely
on the manures made on the farm. Years ago, I was laughed at because I
used guano and superphosphate. It was only yesterday, that a young
farmer, who is the local agent of this neighborhood, for a manure
manufacturer, remarked to me, “You have never used superphosphate. We
sowed it on our wheat last year, and could see to the very drill mark
how far it went. I would like to take your order for a ton. I am sure it
would pay.”
“We are making manure cheaper than you can sell it to me,” I replied,
“and besides, I do not think superphosphate is a good manure for
wheat.” --“Oh,” he exclaimed, “you would not say so if you had ever used
it.” --“Why, my dear sir,” said I, “I made tons of superphosphate, and
used large quantities of guano before you were born; and if you will
come into the house, I will show you a silver goblet I got for a prize
essay on the use of superphosphate of lime, that I wrote more than a
quarter of a century ago. I sent to New York for two tons of guano, and
published the result of its use on this farm, before you were out of
your cradle. And I had a ton or more of superphosphate made for me in
1856, and some before that. I have also used on this farm, many tons of
superphosphate and other artificial manures from different
manufacturers, and one year I used 15 tons of bone-dust.”
With ready tact, he turned the tables on me by saying: “Now I can
understand why your land is improving. It is because you have used
superphosphate and bone-dust. Order a few tons.”
By employing agents of this kind, the manufacturers have succeeded in
selling the farmers of Western New York thousands of tons of
superphosphate. Some farmers think it pays, and some that it does not.
We are more likely to hear of the successes than of failures. Still
there can be no doubt that superphosphate has, in many instances, proved
a valuable and profitable manure for wheat in Western New York.
From 200 to 300 lbs. are used per acre, and the evidence seems to show
that it is far better to _drill in the manure with the seed_ than to sow
it broadcast.
My own opinion is, that these superphosphates are not the most
economical artificial manures that could be used for wheat. They contain
too little nitrogen. Peruvian guano containing nitrogen equal to 10 per
cent of ammonia, would be, I think, a much more effective and profitable
manure. But before we discuss this question, it will be necessary to
study the results of actual experiments in the use of various
fertilizers for wheat.