FERTILIZERS FROM WASTES
Nourishment is as essential to the land as it is to the animal kingdom.
This is particularly so in countries, such as the British Isles,
where the land has been worked assiduously, year after year, for
centuries. The co-relation between fertilizers and crop yields is too
obvious to demand other than mere mention. The main problem, in such
circumstances, is to secure sufficient quantities of the nutritive
constituents necessary, and at a price which shall render their
utilization profitable to the farmer, and enable the resultant food
products to be brought within the reach of the public at an attractive
figure.
The worship of hygiene and the introduction of practices conducing
to the enhanced health and welfare of the community have served to
deprive the land of a heavy proportion of that food which, under
primitive conditions, it freely receives. Furthermore, the contemporary
agriculturist is not content with receiving from the land just what
Nature, if left to herself, is disposed to contribute. He practises
forced or intensive measures, and in so doing naturally accelerates and
accentuates the exhaustion of the soil.
In so far as these islands are concerned--it was equally applicable to
other countries similarly affected--the stringency in natural manures
was aggravated by the acquisition of all available horse-power for
the battle-fronts as well as the need to husband straw for military
foraging purposes. So, to ensure the safety and yield of his crops, the
farmer has been compelled to fall back upon divers substances, natural
as well as chemical, or as they are more popularly termed, artificial
manures, although the word “artificial” in this interpretation is
somewhat ambiguous, seeing that the materials employed, for the most
part, enter into the scheme of Nature.
Under normal conditions British soil was liberally fed with these
chemical fertilizers, especially of superphosphate, nitrate of soda,
and potash. And for all of these three indispensable soil-foods
we were dependent upon foreign sources of supply, which naturally
suffered interruption more or less as a result of the outbreak of
hostilities. During 1913 we imported 970,185 tons of these manuring
agents, for which we paid £3,333,612--$16,668,060. These figures do
not include potash, appreciable quantities of which, drawn from the
German mines, were used. But, taking the other two materials, phosphate
occupied first place in point of quantity with 539,016 tons valued
at £874,166--$4,370,830--while the Chilian nitrate claimed premier
position in value at £1,490,669--$7,453,345--for which we received
140,926 tons.
Owing to the availability of the foreign manures there was a tendency
to turn a blind eye to our own producing capacity in regard to
plant-foods of the chemical order. But such an attitude was quite in
keeping with the British character; we preferred to pay compliments, in
the form of money, to other countries at the expense of our own. With
war we learned the folly of our ways and received an awakening, rude
but fruitful.
Of the artificial fertilizers essential to plant life we can supply all
with the possible exception of the superphosphate, although in this
instance we are striving to develop our home resources. Chilian nitrate
may be superseded by the atmospheric nitrates: we can derive all the
potash we desire by the observance of the necessary care and the
lessons which science in its various phases is able to extend. Possibly
the results may not be so prolific as when the imported articles are
utilized, but this is merely a matter of opinion, and one upon which
even experts agree to differ.
Of the domestic contributions to the artificial fertilizer issue, those
which have attracted the greatest measure of attention are sulphate of
ammonia and basic slag. So far as the first named, of the nitrogenous
group, is concerned, a remarkable reversion of opinion is to be
recorded. Prior to the war the British farmer, despite the fact that
sulphate of ammonia was obtainable in relatively large quantities from
home sources, was not deeply impressed with its plant-feeding value.
At all events the domestic consumption was relatively low, 60,000 tons
being the maximum amount used in any pre-war year. But what the British
yeoman disdained, his foreign contemporary seized with avidity. During
1913 our exports of this waste, or by-product from our gas-works and
coking-ovens, totalled 323,054 tons worth £4,390,547--$21,952,735--out
of a total export of 704,071 tons of fertilizers valued at
£5,745,484--$28,727,420. France and Spain, as well as our sugar-growing
Dominions, were our largest customers, the farmers of which were
prepared to pay more for this soil stimulator than were their
contemporaries at home. But, as a result of experience gained under the
stress imposed by war, sulphate of ammonia found greater favour in the
eyes of our husbandmen. During 1916 the home consumption increased by
15,000 tons, a further 15,000 tons’ improvement was recorded during the
first three months of 1917, while for the 1917 season the figure rose
to 150,000 tons.
Under normal conditions, in accordance with the law of supply
and demand, prices tend to rise coincidentally with the enhanced
manifestation of request, but the country took steps to protect the
consumer, and at the same time to remunerate the producers adequately.
Whereas the pre-war price for this fertilizing agent ranged from £12
10s. to £14--$62.50 to $70--per ton, the war price was officially fixed
at £16--$80--per ton. Inasmuch, however, as the controlled quotation
included transport and delivery charges, the actual increase in the
cost was not appreciable.
But it was the 1917-18 season which revealed the circumstance that
the virtues of sulphate of ammonia at last had really gripped the
British farmer. From the estimates which were carefully prepared the
requirements were set down at 220,000 tons. As a matter of fact they
notched 230,000 tons. Thus, in two short years, the consumption of
sulphate of ammonia by the hungry soil of Britain was quadrupled, a
really startling achievement. The total output of this commodity,
both in the solid and liquid forms, reached a round 400,000 tons,
and to-day stands at about 460,000 tons. Approximately, one-half of
this aggregate is forthcoming from our gas-works and the other half
from our coking-ovens and blast-furnaces. During the war the balance
remaining after the needs of agriculture had been met, namely 170,000
tons, was absorbed in the manufacture of munitions. But under restored
peace conditions this latter volume will be rendered available for home
consumption or export.
Seeing that our pre-war export figure was 323,054 tons a year, it would
seem as if we are destined to lose some of our revenue from this trade.
Obviously only about 170,000, or at the utmost, 230,000 tons will be
available for our foreign customers. It would seem as if we are certain
to fall a round 100,000 tons short of their actual needs, which will
certainly be equal to the ante-bellum figure. As a matter of fact
the demand will probably be much heavier, considering that the land
of these customers has been denied this food for nearly five years;
at least supplies have only been forthcoming in small and totally
inadequate quantities. Moreover, the home demand is rising still, which
must tend to attenuate the quantities available for export.
But there is no need for us to grow apprehensive. In another chapter
I deal with the benzol question, and illustrate how we might increase
our supplies of a home-produced fuel to displace imported petrol. In
meeting our domestic benzol requirements we can increase our output
of sulphate of ammonia at the same time. The ammonia is the substance
which so worried gas engineers during the early days of gas-lighting.
Then it was an unmitigated curse: to-day it is a blessing. The actual
yield of sulphate of ammonia from a ton of first-class gas-distilling
coal may be set down at 18 lb. However, seeing that this varies
according to the quality of the coal, I will set this figure at 15 lb.,
which is distinctly conservative. On this basis, if the whole of the
coal burned to sheer waste in the private grates of the country, and
which may be set down at 100,000,000 tons under normal conditions, were
first carbonized, it would be possible to add at least 700,000 tons to
our present output of sulphate of ammonia, which would thus be brought
up to approximately 1,160,000 tons a year. This would be quite enough
to satisfy the needs of all our customers. But, at the present moment,
owing to our supineness, the ammonia and the benzol are being allowed
to fly up the chimney. Consequently every person who adheres to the
consumption of coal instead of coke, in the open grate, just because
a blaze is appreciated, is doing his or her bit towards the loss,
assuming the value of the fertilizing agent at the modest figure of £10
per ton, of £7,000,000--$35,000,000--per annum. Truly we are paying
dearly for the gratification of a whim.
Second in popularity among the artificial fertilizers comes basic slag.
This is another waste product, being the refuse from our steel-works.
It has been allowed to pile up in the vicinity of our blast-furnaces to
the detriment and disfigurement of our countryside. But an observant
and persevering individual probed these unsightly heaps to discover
that they contained a valuable food for plants, and in sufficient
quantity to render it remunerative to pulverize the rock-like mass into
a fine powder. Forthwith, where phosphatic content was sufficiently
favourable, the dumps were taken in hand to be ground up into a flour
to be distributed over the soil.
But the story related of sulphate of ammonia was destined to be
repeated in connection with basic slag. It found greater favour in
the eyes of the foreign farmer than it did with the native yeoman,
although in this instance the circumstance that a mistake was being
committed was discovered possibly more promptly. In 1913 our exports of
phosphatic refuse from our blast-furnaces were 165,100 tons, for which
we received £633,034--$3,165,170. The consumption upon our home lands
was about the same, so that the total output was a round 330,000 tons a
year. Here again, once the possibilities of the fertilizer were driven
home, an increased demand set in. From an attitude of indifference
British farmers turned to one of clamour. Fortunately, the first rush
was met by placing an embargo upon the export of this article, and, in
this way, double the quantity was at once secured for native needs.
The demand soon absorbed this extra quantity, and then it became
necessary to increase the output of the article. But in this instance
the problem was not so readily solved. In the first place the farmer
was not disposed to accept this fertilizer when its phosphatic content
fell below 25 per cent. But the proportion of phosphate varies widely
according to the district whence the ore is forthcoming, as well as the
actual smelting process followed. It may range up to as high as 44 per
cent. or more; on the other hand it may fall to as low as 12 per cent.
or less.
Owing to the comparatively limited demand which prevailed for this
article before the war, only comparatively few firms essayed the
necessary grinding of the rock-like waste from the blast-furnaces.
Again it was by no means an easy matter to maintain the slag to the
desired phosphate quality. Another disturbing factor was that the
smelting of steel, in common with other industrial process, is in a
constant state of transition and improvement. This evolution was found
to be affecting the slag very adversely, because the tendency was
towards lowering of the phosphoric acid content.
However, it was discovered that, while the available dumps showing a
phosphatic content of 25 per cent. or more were severely limited, there
were an appreciable number of slag heaps carrying a lower percentage,
ranging down to 17 per cent. of the necessary constituent. These were
taken in hand to be passed through the grinding mills. Even this
contribution proved insufficient. The demand was met only by working
heaps of inferior phosphate quality and adjusting the price according
to the percentage of the phosphoric acid present, the figure naturally
rising as the proportion improved.
The increase in the consumption of basic slag was remarkable. The
1916 figure was double that of 1913, the whole of the 165,000 tons
formerly exported being absorbed. Increased producing facilities and
the exploitation of a lower grade waste, as already mentioned, served
to increase the consumption for 1917 a further 150,000 tons to 500,000
tons, which represented the maximum capacity of the works specializing
in this product. But although the latter could not be extended to
meet the still rising demand, owing to the difficulties encountered
in connection with the provision of machinery, every effort was made
to keep supply astride of demand. Many cement works throughout the
country had been compelled to cease operations owing to the stoppage
of constructional activity and were lying dormant. As these possessed
machinery excellently adapted to the preparation and grinding of the
slag they were pressed into service, especially for dealing with the
lower-grade waste from the blast-furnaces. In this way provision was
made for lifting the output to 600,000 tons or more a year.
So far as the superphosphates are concerned the deficiency experienced
in this connection has not been so easy of solution. Our resources in
the essential material, so far as is known, are somewhat sparse, while
a further problem arose in connection with the sulphuric acid, which
was in keen request for other purposes. The issue was met by continuing
the importation of the crude rock from the northern coast of Africa,
and in this manner we contrived to satisfy our needs. But, during this
period, the opportunity was taken to ascertain whether or no there did
happen to be any suitable rock or other waste which we were neglecting,
inasmuch as the moment war ceased immense quantities of sulphuric acid,
then being absorbed for the production of munitions and other military
requirements, would be released. Investigation was directed once again
to the coprolite beds in the Eastern Counties which were formerly
worked to yield artificial manures of this character, but which had
been abandoned. They were again taken up, and a domestic superphosphate
production industry resuscitated upon a limited scale. But whether
under normal trading conditions it will prove remunerative to continue
this phase of native activity time alone can prove.
The only remaining fertilizer which was a source of perturbation to
the British agricultural industry was potash, which is absolutely
essential to certain lands and specific crops. Germany was in the
position to dominate this industry throughout the world, and she did
not hesitate to wield the power she possessed to her own advantage. In
pre-war days we imported about 240,000 tons of this chemical, but the
greater part was absorbed by other industries, such as glass-making, to
which it is vital. Only about 22,000 tons found their way to the land.
Nevertheless, the demand in this, as in other directions, was upwards
and prices rose by leaps and bounds, even touching about £60--$300--per
ton at one time.
Yet we have virtually solved our potash difficulty, and certainly will
be able to meet all farming requirements in connection therewith if we
only sustain our initiative. We have an abundance of waste materials
whence we might obtain all that we need, but for the most part we
have spurned them with disdain. It has been so much easier to procure
our requirements from the country across the North Sea, although,
in expending money in this direction, we materially contributed
towards the construction of the much-vaunted High Seas Fleet. But when
necessity compelled us to cast around to work out our own salvation we
encountered many surprises. Germany will doubtless be equally surprised
in future when she discovers how little dependence we need place upon
her vast resources. During the war potash was in urgent request for
munitions, but the demand in this connection will no longer prevail,
or, at least, only to a limited extent, thereby allowing commercial and
industrial fields to acquire what they need, and at a fair price. We
shall be foolish if we allow ourselves to abandon the exploitation of
our potash-yielding wastes merely by slavishly clinging to the pre-war
price for this commodity, which was about £10--$50--per ton. To do so
will be to sacrifice our national security and wealth upon the altar of
cheapness.
The wastes capable of being persuaded to yield potash are far more
numerous than may possibly be conceived. And this chemical is derivable
from some of the least-expected founts. A Yorkshire gentleman, Mr. E.
E. Lawson, threw a bundle of banana stalks upon his polished office
chair and allowed them to remain there for some time. When he removed
the stalks he noticed that the juice exuding from the stalks had played
sad havoc with the finish to the furniture. This action pointed to the
presence of potash in the juice, and apparently in material quantity to
remove the polish so effectively. So he suggested to a chemical friend,
Mr. R. H. Ellis, that it might be profitable to analyse the contents
of the stalk to ascertain just how much potash it carried. This was
done, and the result was somewhat startling, indicating 45·9 per cent.
of potash and practically no soda. The subject was then investigated
by Dr. A. J. Hanley, of the Agricultural Department of the Leeds
University, and his analysis confirmed the former finding. The dried
matter of the original banana stalk was found to be as rich in potash
as kainit, the popular fertilizer of this class. These investigations
sufficed to establish the possibility of extracting 188 lb. of dried
matter from a ton of banana stalk containing 13·7 per cent. of potash,
or 54 lb. of ash containing 47·5 per cent., or 25 lb. of pure potash.
The yield from the individual ton may seem to be too small to be worth
considering. But reflect upon the normal consumption of bananas in
this country! The annual importation ranges from 7,000,000 to 8,000,000
bunches, which represents an equal number of stalks--mere refuse.
According to Mr. Ellis, under normal conditions the stalks average a
round 4,000 in number weekly in Leeds alone. When stripped, the average
weight of the stalk is 4 lb., so that there are 16,000 lb. of stalk
wasted every week in the Yorkshire city. Properly treated, about 1,340
lb. of dried matter, rich in potash, could be secured therefrom to feed
the land.
Applying the reclamation process to the whole of the country, it
should be possible to secure from 28,000,000 to 32,000,000 lb. of
banana stalk, giving from 2,350,000 to 2,700,000 lb. of dried matter
containing 13·7 per cent. of potash--from 321,000 to 370,000 lb. of
potash--during the year. If the stalks were carbonized they would
yield from 675,000 to 771,428 lb. of ash containing from 320,000 to
366,000 lb. of pure potash. This may represent but a small fraction of
the total agricultural consumption of 22,000 tons per annum, but it
would be a contribution from a waste product which now has to suffer
destruction with the total loss of all beneficial values. The primary
difficulty, of course, would be in connection with the recovery of
the stalks, but a reorganization of our selling methods, such as the
compulsory return of the denuded stalks to the fruit markets for
ultimate bulk collection, would go a long way towards the solution of
this problem. The question arises as to whether we should not find it
advisable to dispose of all vegetable and fruit waste along individual
lines, inasmuch as other refuse of this character contains potash in
varying proportions. By the establishment of a small, inexpensive and
suitable furnace in the markets for the treatment of all waste it
would be possible to recover valuable fertilizing ash in sufficient
quantities to allow bagging and sale upon the spot. Such treatment
would be no more expensive than that in operation to-day, involving
transport to, and combustion in, the destructor.
Tobacco is another product rich in potash, particularly the ash. Here
recovery would prove an exceptionally difficult task, but it has been
suggested that the conservation of ash and the discarded ends of
cigars and cigarettes from clubs, hotels, and other centres possessing
smoking-room amenities might be encouraged. The total during the year
would be impressive. Certainly collection from such quarters would not
be attended with difficulty, while the price payable for the residue
might be made sufficiently attractive as to induce the attendants to
garner this residue.
So far as the exploitation of waste for potash content in this country
is concerned only one established practice, which is extremely
precarious, has ever met with recognition upon a limited scale. This
is the extraction of the precious substance from kelp, or _vraic_, to
mention two of the names under which the familiar seaweed is known.
The treatment of this waste is conducted along crude lines, but it is
doubtful whether our available knowledge could suggest a more skilled
method. British seaweed does not resemble that recovered off the
coasts of Japan and the Pacific seaboard of the United States, where
the recovery of potash from this residue from the sea has become an
established industry.
Yet Britain need not pay a further penny tribute to Germany. We
are able to free ourselves entirely from the German yoke, and can
confidently look forward to such a happy state of affairs so long as
the steel age reigns. The raw material dumped into the blast-furnaces
carries a certain proportion of potash. But it has always been
permitted to escape. Being associated with the fine dust it was borne
through the flues, a certain proportion being deposited therein, but at
least 90 per cent. was irretrievably lost. Threatened famine compelled
us to devote attention to the possibility of arresting this fugitive
potash, and our efforts have met with success. The furnace flue dust
is trapped to be passed through a special plant for further treatment.
Previous to the war the economical and fiscal conditions would not
have permitted such a practice with profit. The requisite plant is
necessarily somewhat costly to install and to operate. Had we decided
upon such a course of action the Germans would promptly have forced the
process into bankruptcy by resort to price-cutting tactics. The Potash
Syndicate was exceedingly powerful, and it never hesitated to wield its
power, as the United States of America have every occasion to remember
when, a few years ago, it came into conflict with the German Government
in regard to inter-trading, and was brought full tilt against the
potash ace of trumps. Had we ventured to dispute the German monopoly
by any attempt to exploit our flue-dust we should have upset a pretty
kettle of fish and should have been bludgeoned into surrender. It is
to be hoped that the authorities will hesitate to play so completely
into the enemy’s hands again, although this is fortunately very
unlikely because the Teuton monopoly has been broken effectively by the
restoration of Alsace-Lorraine to France which carries, among other
numerous advantages in raw materials, the immense potash deposits
which the Germans worked so profitably to their own ends. Still, even
this achievement should not dissuade us from continuing to exploit the
waste dust recovered from our blast-furnaces. Immense quantities of
the essential material are forthcoming, the potash content of which
varies from 3 to 13 per cent. As output increases it should be capable
of recovery at a decreasing figure and at one which should enable the
indispensable product to be placed upon the market at a competitive
figure.
The foregoing does not exhaust the list of potash-yielding wastes
possible of exploitation. It is recoverable from wool in the washing
process; feldspar also contains potash; farmyard manure will yield
it in attractive proportions--from 9 to 15 lb. per ton; while liquid
manure also carries it to the extent of 40 to 45 lb. per 1,000 gallons.
Thus it will be seen that we need never suffer from an actual famine in
potash if we but resolve to exploit our wastes to the utmost.
I have referred in a previous chapter to the value of leather waste
as a fertilizer. Five years ago we did not pursue this problem
along determined lines, mainly because we did not really understand
its preparation, while our farmers did not regard the product then
marketed with favour. But to-day there is a welcome change both in
productive methods and the agricultural attitude. Some large plants
for the treatment of the leather waste have been laid down and are
being brought into operation. Two distinctive treatments are being
followed. In the one instance the curried leather--sheer residue from
the boot factories possessing no other possible use--is being submitted
to treatment for the extraction of the greases and fats used in the
dressing processes. In the second system these fats, owing to their low
grade and as yet absence of possible industrial use, are being ignored,
although they disappear for the most part from the product in the
course of treatment. Otherwise the two methods are broadly identical.
The leather is carbonized and then reduced to a dark greyish powder. In
this form it meets with the full approval of the farmer, and, as its
nitrogen content is said to range up to 9 per cent., it is meeting with
ready disposal, the demand at the present moment being far in excess
of supply. At one works an output of 60 tons a week is being recorded,
which incidentally indicates the quantity of leather waste incurred in
our boot-producing factories.
I have also drawn attention to the extent to which fish scrap is now
being treated, and here again highly satisfactory developments are
to be narrated, the trade, especially in regard to the production
of fertilizer, being in a flourishing condition. Fish guano appeals
to the farmer, owing to its high content of ammonia and phosphate
which aggregate approximately 20 per cent. At one fish waste reducing
factory the output is 20 tons every 24 hours, the plant being run on
continuous lines, but arrangements are being completed to double the
capacity to secure an output of 40 tons during the 24 hours. Hitherto
the farmer has not been completely enamoured of fish manure because
in certain instances, notably in the treatment of the oily fish, such
as the herring, the grease content, which was as anathema to him,
was somewhat heavy. But the perfection of the solvent extraction
process which I have described, and whereby the oil contained in the
finished fertilizing meal can be reduced to as low as 1 per cent., has
completely removed this disability.
As is well known, bone-meal is a popular fertilizer. In this
instance, although the fatty content of the crude bones may be high,
the processes of degreasing have been advanced to such a stage of
perfection as to bring about virtually the total elimination of this
objectionable constituent. The fertilizer, if properly prepared,
will not carry more than 1 per cent. of grease. The bones undergo a
very thorough treatment, because this waste is able to feed several
industries.
Sewage is also coming more widely into favour as a fertilizer, as
I explain in another chapter, while residues incurred in other
ramifications of industry are now being carefully collected instead
of being permitted to dissipate into the air or to pass to the
furnaces for combustion. The dust arising from the reduction of
woollen rags into shoddy forms an excellent hop manure. Dried blood
is another first-class fertilizer--in fact it would be difficult to
enumerate all the wastes which can now be profitably exploited for
their soil-nourishing values. Speaking broadly, it may be stated that
any refuse which, upon investigation, is able to yield 3 or more per
cent. of nitrogen demands further examination for the discovery of
the cheapest ways and means to reduce it to a fertilizer for sale
at an attractive figure. If price be right no apprehensions need be
entertained concerning disposal; the farmer will absorb the plant food,
to nourish his crops, with eagerness.