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.