COMMERCIAL FERTILIZERS AND THEIR BASIS OF SALE.

New Zealand Journal of Agriculture, Volume 43, Issue 3, 21 September 1931, Page 183

COMMERCIAL FERTILIZERS AND THEIR BASIS OF SALE.

J. A. BRUCE,

Inspector of Fertilizers, Department of Agriculture, Wellington.

11. PHOSPHATES SOLUBLE IN WATER— continued.

Concentrated Fertilizers.

The present article deals with those fertilizers of the concentrated class now on the market which have a relatively high percentage of quickly soluble phosphoric acid in their composition. Later on in this series the whole group of fundamentally new synthetic fertilizers, made economically possible by the invention and elaboration, of remarkable technological devices for taking nitrogen -out of the atmosphere, will be discussed from the standpoint of their nitrogenous fertilizing constituents.

Although concentrated fertilizers may furnish valuable amounts of water-soluble phosphoric acid, in the broader sense they must be classed apart from the ordinary or standard-strength superphosphate group dealt with in the July issue of this Journal. What may be regarded as the leading feature of a concentrated fertilizer is that it should possess a high content of either one, two, or three of the fertilizing substancesphosphoric acid, nitrogen, and potashin active or chemically pure form, with the minimum amount of what can be arbitrarily termed unessential material or diluent in its make-up. Diammonium phosphate, for example, a typical concentrated salt of German manufacture, contains, roughly speaking, 74 per cent. (1,660 lb. to the ton) of total plant-food (i.e., nitrogen plus phosphoric acid) practically all in water-soluble form ; whereas a mixture made from standard-strength fertilizers such as are in common use, containing nitrogen and phosphoric acid respectively, may only have a total plant-food content of somewhere about 20 per cent. (450 lb. to the ton). The majority of normal-strength fertilizers carry a single fertilizing ingredient, but may have other mineral elements not officially recognized as saleable plant-foods, such as calcium, sulphur, sodium, iron, and manganese, in their composition; for the present, however, these are tentatively considered not to be required for plant-nutrition in larger quantities than most soils can provide.

The principal sources* of phosphoric acid in the concentrated phosphate class of fertilizer comprise double superphosphate, which consists chiefly of monocalcium phosphate, and the two phosphates of ammoniamonoammonium and diammonium phosphates. These latter, as their names imply, combine the fertilizing compounds of ammonia f (or nitrogen) and phosphoric acid. Both these ammonium phosphates also occur in various commercial grades of new-type fertilizer offered for sale under such trade names as Nitrophoska, EnPeKay, Ammophoska, &c., each combining atmospheric nitrogen with potash and phosphoric

acid in certain fixed proportions. Synthetically produced preparations bearing the three chief fertilizing ingredients in an intimately compounded or combined form for promoting vegetative growth are designated commercially as “ complete ” concentrated fertilizers.

Double Superphosphate.

Double superphosphate, now more commonly known as triple or treble superphosphate, is a form of phosphate hitherto usually manufactured by digesting phosphate rock with sulphuric acid to liberate phosphoric acid, and then using this form of phosphoric acid to decompose further batches of rock. The final product resembles normal-strength superphosphatein fact, it may be more or less regarded as ordinary superphosphate with the gypsum (hydrated sulphate of'lime)* removed. The word “double” has evidently been applied because of the double treatment of the phosphate rock with sulphuric and phosphoric acids. The new term' “ triple ” or “treble” is employed in the fertilizer trade of Canada and the United States, possibly because some concentrated .supers have approximately three times as much plant-food as superphosphate produced by only a single treatment of phosphate rock with sulphuric acid. In comparison with the high-grade superphosphate handled here, the general run of double superphosphates yield a little more than twice as much phosphoric acid.

From the viewpoint of W. Waggaman, a noted technologist, there would appear to be at least one notable economic advantage attached to this method of producing high-strength superphosphate—namely, that relatively low-grade phosphate deposits may be utilized to produce a grade high enough for economic application to the land. Apart from this, however, a number of technical and other objections seem to have hindered the expansion of the process, such as (i) installation and maintenance of expensive plant, (2) somewhat high price of the product, and (3) presence of free phosphoric acid in the fertilizer at. times, causing bag-rotting and scorching of vegetation. Nevertheless, it is only fair to add that any such disadvantages connected with the manufacture of double superphosphate may be entirely eliminated in the future. It is now understood, for instance, that new technical processes for making this fertilizer are operating very successfully in certain countries overseas.

Double superphosphate has been prepared by small plants in Europe for many years, but the output has been limited. In America and Canada, more noticeably in . the past two years, double super have gained a firmer footing in the fertilizer —perhaps as a result of new improved methods of manufacture. Nowadays the chief use of the product is for raising the phosphatic strength of proprietary mixtures. Only recently a large works, erected at a cost of £2,000,000, commenced the manufacture of concentrated superphosphate, together with ammonium sulphate and monoammonium phosphate, at Trail, British Columbia. This company apparently has in view the creation of a market for the three products in the Pacific regions as well as in Canada.

Double superphosphate has not as yet found, a regular place on the New Zealand market, but'has been advertised for sale at £l4 per ton, The unit* or commercial value of this article compared with that of the standard grade is as follows :

Superphosphate. Superphosphate. Superphosphate. Superphosphate. Chemical plant-food as phosphoric acid (P 205 0 5 ) .. .. .. .. 20-2 per cent. 40 per cent. Price per ton (quoted Auckland, autumn, 1931) .. ' .. .. .. £4 17s. 6d. (cash) /14 (cash). Price per unit of plant-food (unit value) . . 4s. rod. 7s.

To the purchaser the higher plant-food content of the double superphosphate would appear to permit of some economy in transportation, handling, and distribution costs ; nevertheless, on the face of it, the standard superphosphate, being 2s. 2d. per unit cheaper, is the better proposition, unless exceptionally high carriage costs are involved.

The plant-food content of double superphosphate ranges between 30 and 52 per cent. (672 lb. to 1,165 lb. per ton), but the grades most commonly sold have between 40 .and 50 per cent, phosphoric acid. If the trade custom of expressing the fertilizing strength of normal-strength superphosphate in terms of tricalcium phosphate (e.g., 44-46 per cent.) is adopted for double superphosphate, some rather awkward figures will arise. A double grade with 52 per cent, phosphoric acid in calcium phosphate equivalency gives a figure somewhere about 113 per cent., which admittedly would be a questionable method of describing quality.

Monoammonium Phosphate.

Monoammonium phosphate is a readily soluble salt made by combining a form of pure, free liquid phosphoric acidf (H 3 PO 4 ) with pure ammonia in correct proportions, and evaporating the solution to dryness. The pure salt is white, dry, and crystalline, and provides 12-2 per cent, of nitrogen and 61-7 per cent, of plantfood phosphoric acid (PO S ). The crude salt more adapted for fertilizing purposes is prepared in the same way, except that the free liquid phosphoric acid employed in the process is utilized in an unpurified state.

Two commercial grades, analysing respectively-! 10-7 or 16-5 per cent, nitrogen and 48 or 20 per cent, phosphoric- acid, have been prepared in granular form under the trade name- of Ammo-Phos at large works in New Jersey, U.S.A., for several years. Both grades were at one time produced- largely for • the convenience of manufacturers wishing to raise the plant-food value of proprietary mixtures. However, more recently the makers have developed an export trade with various tropical countries. - ■

The new line offered from the works at Trail, British Columbia, carries a guarantee of 10-7 per cent, nitrogen and 52 per cent, phosphoric acid. The warranted analyses of various qualities of

ammonium phosphates and “ complete fertilizers, including a new series placed on the market recently by the British chemical combination operating an immense modern plant at Billingham, England, are presented in the following table :

Sales of ammonium phosphates, up to comparatively recently at any rate, have not yet attained any extended volume. A. N. Gray, secretary of the International Superphosphate Manufacturers' Association, London, estimates the world’s total consumption (1928) of calcined rock phosphate (basis, 28-5 per cent, phosphoric acid) for manufacture of ammonium phosphates, Nitrophoska, and similar products at 200,000 tons, which is, roughly, only 1-5 per cent, of the total phosphate 1 rock used for all other purposes of fertilizer-manufacture. According to present information, Japan seems to be about the heaviest consumer of ammonium phosphates— . tons having been brought from Germany and the United States for use in the rice-fields of that country during the year 1929.

Diammonium Phosphate.

Diammonium phosphate, although similar to the monoammonium form, contains a higher proportion of nitrogen. The pure salt is produced as a white, finely crystalline compound when a solution of monoammonium phosphate, or of phosphoric acid, is saturated with ammonia. A marketable grade (Diammonphos 1.G.), designed as a

special fertilizer for garden plants and vegetables, is prepared at huge synthetic ammonia works at Leuna and Oppau, Germany. This substance has been registered in the Dominion for the past four years, but seems hardly to have emerged locally from the experimental stages.* A sample analysed in the Department of Agriculture’s Chemical Laboratory yielded 53 per cent, of phosphoric acid and 21 per cent, of nitrogen.

Without going into the question of landed costs compared with other fertilizers produced or imported here, it may be mentioned that the use of diammonium phosphate as a general-purpose fertilizer is limited on account of its extraordinarily high concentration. Moreover, it tends to cake very hard if stored in a moist atmosphere for any length of time. The material in small airtight packets retailed under the name of Floraphos has a good mechanical condition, and from all accounts is very successfully employed in local home gardens.

Other Concentrated Fertilizers carrying Ammonium Phosphate.

Nitrophoska I.G. — This is the proprietary name given to a group of so-called complete fertilizers sold in several commercial grades. The manufacture of this novel type of concentrated compound was first accomplished by the producers of Diammonphos LG. ; briefly, it is the product of the direct combination of diammonium phosphate with ammonium nitrate and potassium chloride or sulphate.

The following represents the quality of the article imported for local consumption : Nitrogen soluble in water, 16-5 per cent. ; phosphoric acid soluble in water, 15-2 per cent. ; phosphoric acid insoluble in water, 1-3 per cent. ; potash (K 2 O) as chloride soluble in water, 20 per cent. Particulars of another grade formerly registered for sale may be seen in the table (opposite page). The analysis of EnPeKay, manufactured in similar fashion to Nitrophoska and registered for sale in the Dominion, is also shown in the table.

Almost all the Nitrophoska brought into the Dominion has been delivered for use in orchards, tobacco-plots, and market gardens; small quantities have also been used for top-dressing pastures and for field experiments. Considerable success has attended the latest efforts of the makers to surmount the caking difficulty by packing this and other crystalline concentrated fertilizers in granular form in special waterproof bags. If the mechanical condition is good, a cyclone seedsower is reported capable of distributing light dressings uniformly on areas of land that are not available to horse-driven distributing machines.

Leunaphos 1.G., another compounded chemical plant-food of German origin, is prepared by mixing 40 parts of diammonium phosphate with 60 parts of sulphate of ammonia,, and contains 20 per cent, of nitrogen and 20 per cent, of phosphoric acid. Leunaphos has been sold here in experimental amounts only, and is registered for sale under our Fertilizers Act.

Potassium Ammonium Phosphate. — The recent development on a semi-commercial basis of this product, bearing nearly 80 per cent.

of plant-food (1,790 lb. to the ton), is credited to the Fixed Nitrogen and Research Laboratory of the. United States Bureau of Soils, and from all accounts success has attended its employment in field trials with potatoes in Maine. The. guaranteed constituents are: Nitrogen, 5-4 per cent. ; available phosphoric acid, 56-0 per cent. potash, 17-0 per cent.

Some further Recent Developments.

Present indications - seem to point to the adoption of dicalcium phosphate as a component of certain high-analysis “ complete ” fertilizers in place of ammonium phosphate, which heretofore has been the' most popular. The introduction of the former, which has the important nutritional element calcium as an ingredient, is considered more advantageous for special soil-types. .

A recent issue of the American Fertilizer Journal states that a new product of somewhat lower concentration, Kalkammon Phosphat, consisting, as the. name suggests, of lime, phosphate, and ammonia, is now on the market. Two grades are sold: (1) 7 per cent, nitrogen and 17 per cent, phosphoric acid. (2) 12 per cent, nitrogen and 12 per cent, phosphoric acid. Yet another addition to the concentrated group on the market is an ammonium magnesium phosphate, produced by a French company, with a guarantee of 22 per cent, phosphoric acid, 5 per cent, of nitrogen, and 13 per cent, of magnesia.

Ammoniation of superphosphate : A process showing considerable promise of expansion is one in which nitrogen, in the form of ammonia is sprayed into superphosphate or a mixture of superphosphate with other fertilizing agents, whereupon the ammonia is fixed by chemical reaction with the superphosphate. Numerous reports confirm the idea that such a method is neither expensive nor complicated in operation, the finished product, which can be manufactured to almost any desired formula, being prepared from the cheapest plant-food materials.

An Overseas Opinion based on Field Tests.

In discussing results obtained from large-scale field tests, controlled by the United States Department of Agriculture, with various concentrated and ordinary strength fertilizers, Maine Experiment Station Bulletin No. 350 puts forward clearly some of the advantages and possible disadvantages of the new concentrated class of fertilizer chemicals as a whole. From the following extract it would almost seem that there is no class of fertilizer being produced to-day which offers as interesting a future as do the concentrated fertilizers.

■ 1 ■ Economic Advantages. —-The economic advantages of concentrated fertilizers deserve serious consideration. Less handling, hauling, and storage are required at the factory or mixing-plant for concentrated fertilizers. Fewer bags are required. A marked. reduction in freight is made possible. After, the fertilizer reaches the farm, less handling, hauling, and storage are involved. At planting-time fewer trips are required to haul the fertilizer to the field, and the bags can be set from two.;to three times farther apart. -

Taking the entire range of costs involved in manufacturing, shipping, and application of the tonnage of concentrated fertilizer referred to as

compared to the greater tonnage of the 'ordinary-strength fertilizer, concentrated fertilizers offer a good chance to effect certain economies. Future developments will depend on the cost of materials common to those of ' ordinary strength.

Possible Disadvantages.— One of the main difficulties likely to be encountered with certain combinations- of concentrated fertilizer salts is that of poor physical condition. • Salts which possess that property of absorbing moisture from the atmosphere are the chief offenders. A moist fertilizer cannot be distributed evenly. A badly caked one calls for extra labour to get it in the proper shape for drilling with fertilizerdrilling machines.

Other reputed objections to the concentrated fertilizers have been that they would be too hard to distribute uniformly with existing fertilizer-distributing machines ; that they would leach from the soil too readily ; that they would tend to leave the soil in a poor condition if used continuously ; that the salts used in their production would be so pure that the absence of certain other elements might prove detrimental to crops ; and that, above all else, they would lower the yield in comparison with ordinary-strength fertilizers.

These objections are not to be taken so seriously now as they once were, and it is reasonable to expect that any awkward physical condition will be taken care of satisfactorily, as will the matter of developing suitable fertilizer-distributing machines for applying concentrated fertilizers uniformly and getting them well mixed with the soil. It is true that some of these objections may be legitimate, but studies under field conditions, involving different types of soils and crops, will be required before definite decisions can be reached. It is quite evident that the use of concentrated fertilizers has opened up new problems alike for the fertilizer-manufacturer, the manufacturer of fertilizerdistributing machines, the fertilizer consumer, and the investigator of soil and fertilizer problems. ...

Commercial Application of Concentrated Fertilizers

The drift in the fertilizer industry' to-day is showing a definite turn toward the higher-grade types of fertilizer that can be economically produced. Continued progress is being made in raising the plant-food value of fertilizers and at the same time lowering their cost. In Europe, where the fertilizer industry had its inception, the production of concentrated fertilizers was showing signs of great expansion until the prevailing general trade depression set in, necessitating a very drastic curtailment of production. Germany, with her enormous industrial plants, may be cited as the home of the synthetic (air) nitrogen industry ; in 1928 she . was the chief fertilizerconsuming country of the world as regards potassic and nitrogenous fertilizers, . and was second only to the United States in phosphate consumption. The chemical industries of Britain have also made notable advances in the fertilizer field of late years.

The New Zealand fertilizer -user has now become ' accustomed to buying standard high-grade- fertilizers ; but it is quite within • the range of probability that in the course of time well-balanced, readily available, concentrated fertilizer combinations may enter a little more into our systems of fertilizer practice—more particularly perhaps for increasing plant-food contents, of. proprietary mixtures and for use in remote inland districts where transport charges are heavy. Concentrated fertilizers are constantly being hailed as the

fertilizers of the future, but before finding increasing acceptance on the Dominion, market accurate information will need to be available as to their economic employment and their effects on plant growth and composition under our manifold variations of soil and climate.

Knowledge of the reactions of plants and seeds to concentrated fertilizer salts is indeed very limited, and despite great' advances in the technology of manufacture, making it practicable for almost any desired concentration of the three main fertilizing elements —phosphorus, nitrogen, and potassium —to be made up, other elements are needed to ensure the nutrition of plants on certain soil-types. Here, again, chemical ingenuity will be. called upon to play a part in deciding what mineral elements should be included in the fertilizerbag or used in conjunction with concentrated fertilizing - agents bearing the three so-called essentials.

Dr. Crowther, of Rothamsted Experimental Station, England, writing on “ Soils and Fertilizers in Reports of the Progress of Applied Chemistry ” (Vol. 15, 1930), draws attention to the fact that in connection with the American tobacco crop there is evidence that the application of the newer highly concentrated fertilizers is leading to symptoms of magnesium and calcium deficiency. Dolomitic limestone, which combines these two important elements, is one of the agents applied as a corrective.

With the advent of numerous and in some cases costly highanalysis chemical fertilizers on the market, an understanding of their fertilizing strengths becomes an imperative necessity. Unless the consumer knows what a fertilizer contains it is difficult for him to attribute results to the real fertilizing cause or to know how to supplement the main fertilizer constituents with other materials that may be essential for maintaining the quality and production of his crops.

In all countries chemical fertilizers are sold on the basis of their content of phosphoric acid, nitrogen, and potash, as the case may be. Practical experience has shown that commercial and agricultural values . assigned to them must be judged with, scientific accuracy. The rate of application per acre, for example, must also be governed by the analysis of the product employed. Therefore it is only by the interpretation of the true analysis' that the relative merit of a fertilizer can be determined before being applied to the land. Now, unfortunately, the “ unitary system ” for evaluating fertilizers* is becoming increasingly difficult and more complicated, as a result of the multiplicity of grades and forms of fertilizers manufactured.

Unless one is assured of the analysis, the buying of fertilizers involves a certain degree of risk. On those occasions, then, when fertilizer is bought, the purchaser should take particular notice of the brand and analysis supplied on the vendor’s invoice certificate, f Should any difficulty be experienced in understanding the nature of the information furnished, the nearest agricultural instructor or adviser should be consulted.

* Sodium and potassium phosphates apparently have not yet been offered on the fertilizer markets, except perhaps in experimental amounts, and are therefore not included. f Ammonia contains 82-25 per cent, nitrogen and 17-75 per cent, hydrogen chemically combined. . . ' ■

* A ton of ordinary superphosphate contains about 10 cwt. of gypsum.

* Unit value is the value of 1 per cent. (22-4 lb.) of nitrogen, phosphoric acid, or potash in their respective forms in 1 ton of fertilizer. f Now produced by the electric-furnace method. • ' ■

* Form in which potash (K2O) occurs not given.

* References : (1) Bell, J. E., Manuring of Early Potatoes: Experiments at Pukekohe in 1930.” N.Z, Journ. Agric., Vol. 42, 1931. (2) Cawthron Institute Pasture Research Publications Nos. 3 and. 5. \ . ■ '. t

* It is intended to devote some attention to the unitary system of valuation of fertilizers in a later contribution to the Journal. ■{■Reference: “The Purchase of Fertilizers,” by F. T. Leighton, in this Journal for June, 1930. ‘ • (Series to be continued.) ■

Name of Fertilizer. Nitrogen soluble in Water. Phosphoric Acid. Potash soluble in ■ Water. Soluble in Water. Insoluble in Water. Per Cent. Per Cent. Per Cent. Per Cent. Double superphosphate Per Cent. Per Cent. 40 to 50 Per Cent. Per Cent. Monoammonium phosphate (a) («) 10’7 IO • 7 48-0 48-0 (Ammo-Phos) Ditto . . .. (6) (&) 16-5 i6-5 20-0 20-0 Diammonium phosphate 20-6 52'5 Leunaphos .. .. ... 20-0 20-0 Nitrophoska. . .. (a) (a) i6-5 i6-5 15'2 15'2 1’3 1’3 20-0 20-0 " „ .. .. (b) (as chloride) ,, 15-5 I 5’5 14-2 14-2 1’3 (as chloride) 1’3 ig-o 19-0 (as sulphate) Potassium ammonium phosphate 5'4 56-0 (as sulphate) 17-0 N.P. ammonium phosphate 5’4 56-0 17-0 Series— Type A . . 14’3 43’0 Type B i8-o 18-o Type C i6-o 32-0 Type D 12'3 56-5 Complete series* — 12-3 56-5 No. i (EnPeKay) . . 12-5 12-5 15-0 No. 2 .. . . • 10-4 10-4 20 • No. 3 io • 4 20'8 10-4 No. 5 8-o 16-0 5 * 5 16-0 No. 6 7 ’ 5 26-0 6-o 7'5 No. 7 6'5 22'5 3'0 13-0

Table showing Plant-food Contents of Typical Concentrated Fertilizers bearing Watersoluble Compounds of Phosphoric Acid.