CHAPTER XVII
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.