INDUSTRIAL AND ENGINEERING CHEMISTRY
1112
gators no attempts have apparently been made to establish complete equilibrium. It is noteworthy, however, that there is such close agreement between the results from the inde-
Vol. 20, No. 10
pendent laboratories, notwithstanding the differences in types of catalysts, in the probable purity of the reactant gases, the types of apparatus used, and other working conditions.
The Second International Nitrogen Conference‘ Firman E. Bear THEOHIOSTATE UNIVERSITY, COLUMBUS, OHIO
T
HE first international nitrogen conference, held a t Biar-
ritz, Spain, in 1926, having proved worth while, a second conference was called for 1928. This second conference, sponsored by the nitrogen syndicates of France, Italy, Norway, England, and Germany, was held on board the 5’. 5’. Lutzow sailing from Venice and cruising the Adriatic Sea from April 30 to May 8. Altogether fifteen countries were represented, including the United States and Canada. About one hundred and fifty people were in attendance. A number of delegates having brought their wives and daughters along, the conference was, in part, a social affair including dinner parties and dances on board and excursions over the cities and out into the country a t the ports of call, which included the Island of Corfu, Greece, and Cattaro, Ragusa, Spalato, Sebenico, and Brioni on the Jugoslavian Coast. From time to time during the trip, the ship’s bugler called the delegates to conference where consideration was given t o various matters relating t o the production and utilization of nitrogen fertilizers. The first address, given by Julius Bueb, of the Stickstoff Syndikat of Berlin, Germany, dealt with the problem of nitrogen economics.
Nitrogen Economics In this address it was pointed out that world prices for nitrogen have been decreasing since the spring of 1923 while average prices for the products of the farm have been on the increase during this same period. I n Germany, for example, assuming that 1 pound of nitrogen will produce 20 pounds of grain, as the experimental work with this element indicates, a dollar invested in nitrogen in 1923-24 and applied to the cereal crops produced a return above the cost of the fertilizer of $1.82. In 1926-27 this return amounted to $3.81. As a result there was a marked increase in consumption of nitrogen in Germany which, duing.the year 1926-27, reached a total of 400,000 metric tons of the element. The world total for that year was 1,339,000 metric tons. This is equivalent t o nearly 6.5 million tons of sulfate of ammonia or over 9 million tons of nitrate of soda. In satisfying this demand for nitrogen the air-nitrogen industry has enjoyed tremendous growth. Of the world total production of over 1,600,000 tons of nitrogen estimated for 192728, considerably less than half had its origin in Chile and in byproduct coke ovens. The development of the air-nitrogen industry, therefore, not only resulted in reducing the cost of nitrogen to the farmer, but made it possible to meet the increased demand for this element resulting therefrom. As Doctor Bueb said, “the synthetic nitrogen industry saved the world from high prices and famine” following the World War. A further important contribution has been the production of a considerable variety of nitrogen compounds such as are needed best t o meet the requirements of the several crops when grown under the wide variety of soil and climatic conditions that obtain in the different parts of the world. In this connection particular mention was made of the reception given to nitrate of lime, which must be regarded as being at least equal in value to nitrate of soda and even superior for those soils that are deficient in lime. 1
Presented at fertilizer conference held at Wooster, Ohio, July 2 , 1928.
The synthetic nitrogen industry may also be credited with stimulating investigation of the possibilities of the commercial production of very concentrated fertilizer compounds. Particular mention was made of Nitrophoska, a complete fertilizer containing as high as 60 per cent of nitrogen, phosphoric acid, and potash combined. Five types of Nitrophoska, having different formulas and analyses, are being sold in Germany and are being used by farmers with good results. , In commenting on Doctor Bueb‘s paper, the writer called attention to several questions raised which appeared to him to be of considerable significance t o the agriculture of the United States. The first was the fact that nitrate of lime, in contrast to nitrate of soda, would seem t o be well suited t o the needs of crops that are, being grown on alkali soils as well as on those that are deficient in lime. The production of highly concentrated complete fertilizers, of which Nitrophoska is an ideal type, merits all possible encouragement. The ultimate economy in freight and handling charges is apparent. But there are equally important reasons for inueasing the concentration of fertilizers. With high concentration is associated high solubility and availability. Constituents having harmful or, a t least, unnecessary effects are eliminated. The tendency on the part of the farmer toward a one-sided fertilizer program is avoided. The quantities of actual nutrients applied per acre are quite likely to be larger if concentrated fertilizers are used. The net effect of their use is a considerable increase in agricultural efficiency. There is now a marked tendency in central United States toward a larger use of complete fertilizers carrying more nitrogen and potash. The using up of the store of virgin fertility in the soils of this country; the growing intensity of our agriculture; the lower cost of fertilizer nitrogen; and the tendency toward row applications of fertilizers for such crops as corn all operate to move the practice in that direction. In Ohio, for example, the consumption of nitrogen increased from 1729 tons in 1924 to 2893 tons in 1927. Likewise potash consumption increased from 7502 to 8963 tons, while the quantity of phosphoric acid used during the same period decreased from 51,983 tons t o 41,181 tons. In the adjustment that has been taking place between the country and the city in the United States during the last eight years, over three million people have been lost from the farm. Economic pressure has caused in part a reversion of poor cultivated land to pasture, waste, and forest, and in part a more efficient use of both land and labor. I n the latter case the acre consumption of fertilizer is increased and more power machinery is used with each reduction in the cost of these commodities. Tractors and combines are substituted for horse and man labor. Other similar adjustments are being made. There is still abundant opportunity for choice between increasing the acreage under cultivation and farming more intensively the land already under the plow. Cheaper nitrogen would seem to Favor the latter, since it offers distinct possibilities as to increased yields of the cereal and other field crops and a t the same time permits of more effective utilization of pasture land than has hitherto been possible. In fact, if abundant supplies of cheap nitrogen become available and the response to propaganda in
October, 1928
1 N D USTRIAL AND ENGINEERING CHEMISTRY
favor of its use in much larger quantities is as rapid as one might expect, a still larger acreage of land than has been under cultivation may revert to pasture and forest, notwithstanding the fact that the population of the Lnited States is increasing at the rate of about two million annually. Several points in connection with the possible uses of nitrogen in the United States merit considerable investigation. For example, 100 bushel-per-acre corn crops often follow the plowing under of a green crop of sweet clover which frequently contains as much nitrogen per acre as is found in 1000 pounds of nitrate of soda. In those areas or under those conditions in which it is not feasible to plow under sweet clover, heavy applications of nitrogen to this crop might prove worth while. Drought injury, commonly recognized by “dying” of grasses and “firing” of corn, is probably due to nitrogen starvation as a result of the stopping of microorganic activities in the dry surface soil. There is considerable evidence that these effects can be overcome by applying nitrogen fertilizers. A given amount of water will produce much increased yields if the crop is abundantly supplied with nitrogen and mineral nutrients. If the fertilizers a t first applied are so chosen as to cause the development of extensive root systems, the plant should continue t o grow when the period of drought has arrived, if attention is paid to applying large amounts of available nitrogen before the time of greatest need for this element has arrived. American experiment procedure in the use of nitrogen fertilizers leaves much to be desired. The belief that legume crops must be depended on for practically all the nitrogen required in extensive farming has prevented adequate consideration of the possibilities in the use of commercial nitrogen. The time of application of nitrogen, as well as the quantity t o be applied, is a distinctly different problem, depending upon whether the plant is an annual, a biennial, or a perennial; the period of the year in which growth takes place; the climatic and seasonal factors involved; and the part of the plant or the quality which is of greatest economic importance. Abundant supplies of cheap nitrogen are resulting in forcing highly important adjustments among the several agricultural regions of the world. They guarantee the capacity of the world to produce adequate supplies of food for its growing population for many years to come. They have again set aside the hope of the farmer of securing materially higher prices for the products of his farm through limitation of supply. Problems Involved in Increased Production a n d Cons u m p t i o n of Nitrogen Fertilizers The next paper was presented by F. C. Speyer, representing h-itram, Limited, of London. Consideration was given to some of the problems involved in the production and consumption of rapidly increasing amounts of nitrogen fertilizers. The world production of nitrogen by 1930-31 was estimated a t 2.5 million tons of the element, equivalent to nearly 12.5 million tons of sulfate of ammonia. In considering the question as to whether the consumption of this large amount of nitrogen would result in the production of an excess of food, notwithstanding the growth in world population, Speyer concluded that there was reason to expect that this might occur, with rather serious economic disturbances both t o the nitrogen industry and t o agriculture. It was pointed out that, in view of the possibility of such difficulties, the prosperity of the farmer must be the primary concern of organized industries dependent upon farming, of which the nitrogen industry is one of the best examples. This requires not only that the credit facilities of farmers be improved but that every assistance be rendered them in securing economic prices for their products. Carl Bosch, chemist for the German synthetic nitrogen industry, commenting on this subject, said that it must not be expected that nitrogen prices would continue to decrease indefin-
1113
itely. Furthermore, cheaper nitrogen would not solve the farmer’s economic problems. An increased efliciency in production was demanded of agriculture as well as of industry. In his opinion industry might well take such steps as would help relieve the farmer of all his tasks save that of production so that he might give his undivided attention t o doing it more economically. Cultivation of Soil in Relation t o Nitrogen Fertilizers 1,ucien BretigniCre, of the &ole Nationale d’Agriculture de Grignon, gave a very interesting address on “Cultivation of the Soil in Relation to Nitrogenous Fertilizers,” a significant feature of which was the comparison of the nitrogen needs of northern France with those of her colonies on the coast of Africa. In the former region, where the advantages of thorough cultivation are well known and the various tillage operations are carefully and systematically done, not only are large amounts of manure applied to the soil and green-manuring crops of alfalfa and clover plowed under, but heavy dressings of nitrogen fertilizers, in a great variety of forms, are applied as well. One factor is lacking. The temperature is not high enough. There is no evidence of microorganic activity before April. This is too late to insure the assimilation of adequate amounts of nitrogenous food by winter cereals which, because the soil is deep and the rainfall relatively high and well distributed, produce a dense growth of strong plants. Nitrogen fertilizers in readily available form must be supplied. In the case of oats the necessary nitrogen is applied before seeding. For sugar beets part is applied before the seeds are planted and part later. In Tunis, Algeria, and iMorocco cultivation is also thoroughly done by modern machinery. However, i t is much more superficial, since it has for its primary purpose the accumulating and conserving of water, Only one harvest can be gathered every two years. Yet when the plants are started, rapid growth takes place. Nitrification is early apparent. Nitrogen fixation is probably relatively active. Fertilizer nitrogen is not only unnecessary, but produces injurious effects. Bretigniere raised the questions, “How can North African agriculture carry a biennial cereal crop without the use of organic substances, without livestock, and without green-manures? Why do yields not decrease? Why is it that they sometimes increase?” He pointed out that this problem had not been adequately studied and indicated the belief that a change in the system would ultimately become necessary. The time of application of nitrogen fertilizers as well as the nature of the material to be applied should receive consideration in this connection. Whereas it was shown that systematic cultivation of the soil does not necessarily set aside the necessity of the use of nitrogen fertilizers, yet it is evident that some relationship exists in any given region, between the amount of working the soil receives and the amount of nitrogen it may be necessary to apply for OPtimum yields. It seems probable that the number of tillage operations might be reduced and the amount of nitrogen applied increased, or vice versa, depending upon the relative costs of these two means of meeting the needs of the crop for nitrogen. There is, of course, a lower limit of tillage below which one cannot go and keep the soil clean and free of undesirable weeds and soil organisms. As BrCtigniere indicated, there is no incompatability between the use of nitrogenous fertilizers and soil cultivation, however perfect. Irrespective of cultivation, “nitrogen fertilizers are invaluable whenever there are symptoms of nitrogen starvation such as occur as a result of crop rotation, the tillering of cereals, the vegetative growth of beets and potatoes and the development of all kinds of meadow herbage.” Agricultural Education Sir Frederick Keeble, director of agricultural research for Nitram, Ltd., presented a paper dealing with the question of agricultural education, in which he pointed out that, in his opin-
1114
I-VDUSTRIAL A V D ENGINEERIXG CHEMISTRY
ion, the present system “errs first by excess of ambition and second by lack of persistence.” It aims too high and fails to recognize the persistence of ignorance and indifference. Proceeding on this assumption, Keeble would use practice as the basis. Science would be employed only after practice was thoroughly understood. All students in agricultural schoolsexcept perhaps certain peculiar investigational type-would first be required to become competent farmers, and only after efficiency in this had been acquired would they be taught any science a t al! in their agricultural curriculum. A farmer would be taught t o grow one crop well. From this he might then quickly learn to grow other crops well. Achieving these successes, he might be in a mood to learn something of the sciences which underlie successful crop production. The extension program should be one of “reiteration and diversification.” Having exhausted all one’s ingenuity in devising means of bringing home the truth t o farmers, one must set about to devise new methods. The publication of an important fact that science has discovered does not assure that those who could use this fact to advantage are aware of it. Economic Principles of Fertilizer Use A carefully prepared paper on the natural economic principles governing the use of fertilizers was read by Hermann Warmbold, formerly professor of agricultural economics a t Hohenheim College, Germany, and now associated with the I. G. Farbenindustrie of Berlin. He pointed out that as a result of scientific approach to this problem, lower costs of fertilizers and much increased concentration had resulted which permitted considerable economies in their use. Figured in terms of potatoes, and for the fertilizers that are normally applied t o this crop, the cost of this fertilizer today, in Germany, is only about 50 per cent of what it was in 1913. As a result fertilizer consumption has been very considerably increased. Progress in the scientific manufacture of fertilizers had been greater than the progress in the science‘of their use. In this connection certain problems present themselves for solution t o agricultural scientists. Among these was mentioned the fact that “soil fertility” is measured in terms of harvest yields without knowing the relation of the different factors, one to another, which determines these yields. Since one or another of the climatic factors has a predominating influence in different regions, it is desirable to know whether it is this factor as such or some relationship existing between this factor and the other climatic factors which is responsible for fluctuations in yield. For one crop it may be rainfall alone. For another crop the relationship of rainfall to the other climatic factors may be of greater significance. The first theoretical investigations of this problem are at hand. With further development they should attain practical importance. This problem is particularly important in connection with the use of fertilizers. We need to know to what extent deviations from the normal weather influence the effectiveness of fertilizers. The question of the form of chemical compounds that should be used for any given soil, climate, or crop arises anew because of the present possibilities of producing a great variety of compounds for fertilizer purposes. Experience has shown that under some conditions one form is preferable and under other conditions another. These conditions need to be more closely defined. The effect on the soil and crop of the simultaneous introduction of other elements which accompany the essential nutrients must receive further consideration. If it were possible to formulate an equation which would express the effects of fertilizer nutrients in terms of crop yields, then positive or negative values might be introduced into these equations for additional elements that are added in combination with these nutrients. Thus Warmbold suggests, for example, that for certain districts and certain cereal crops:
+
T-01. 20, >io. 10
+
1 kg. N 1 kg. P203 1.25 kg. K2O = 25 kg. grain The ratios in which the several nutrients are recommended to be applied in practice vary markedly from country to country without adequate explanation. Thus, for cereals the recommended ratios in Belgium and Holland are: Belgium, N : P20j: K 2 0 = 1 : 1.4-2.2 : 1.2-2.0 Holland, N : PnOs : K 2 0 = 1 : 2.5-4.0 : 2 . 4 3 . 5 Another important question is that of the relationship between easily and not easily soluble nutrients in plant nutrition. The farmer is today the only producer of slowly available fertilizers in the form of plant residues, green-manures, and animal manures. It is conceivable that industry may sometime be called upon to produce similar material, if it is ultimately shown that these two types of materials have correlated functions. In connection with plant genetics, Warmbold called attention to the necessity of developing new races of plants that will meet the requirements under conditions in which much higher quantities of artificial fertilizers are applied than a t present. Plant breeders should take into consideration the intensity of the soil practices that may obtain when the strains with which they are now working are subsequently put t o practical test. Progress in this sphere offers possibilities of great economic significance. Dealing next with the economic aspects of the problem, a comparkon was made of industrial and agricultural production in which significant differences were pointed out. In the former, complete mastery of the physical processes are obtained. In the latter, life processes are concerned which do not permit of complete control. Human labor cannot be economized to such an extent in agriculture as in industry. Agricultural machinery deteriorates as much through non-use as through use, since it cannot be used continuously. Advance in factory production may mean use of entirely new process. In agriculture progress is secured only by better adaptation to the unchanging processes of life. In pre-war times it was generally accepted that the net value of one year’s output of industry was about equivalent to the capital investment. On this basis, 6 per cent had to be deducted for interest. Agriculture usually succeeds in recovering not more than 20 per cent of its capital in the course of a year. The interest charges on the proceeds are therefore five times as high as in industry. It follows that agriculture is affected to a much greater extent by changes in interest rates. As compared with pre-war years, building costs in Germany have advanced from 100 to 180; machinery to 125-130; concentrated feeds to 140; and fertilizers have fallen to 82 (assuming that complete fertilizers of the 1:1:1.25 are used). If the amounts invested in these various commodities before the war were economically adjusted, it follows that the opportunity for a profit is now greater on fertilizers than on any of the others, particularly buildings. This is especially true when one considers the speed of recovery of capital costs in fertilizers and the high rate of return which they normally yield on the investment. An interesting fact developed by Warmbold was that, because of much improved facilities for world transportation, price fluctuations in agricultural commodities have materially increased. Formerly poor crops tended to synchronize with high prices, . b u t this no longer holds. It was pointed out that the fundamental importance of a proper balance of agriculture and industry in any country was such that it was economically sound to give the farmer an advantage in interest rates and in taxation in order that he might enjoy adequate prosperity. Crop Intensification in Relation to Plant Breeding A very stimulating address was given by Erwin Baur, director of the Institute of Plant Research of Berlin, on crop intensification in relation to plant breeding. In this address the progress in the science of plant breeding was reviewed and some interesting
’
October, 1928
ISDCSTRIAL AA’D E-VGINEERING CHEIIIISTRY
suggestions of particular significance to the fertilizer industry were made. Plant breeders have the power of creating new races of plants possessing nothing but good characters, and given a race of plant having only one good character, that character can be isolated and the rest discarded. This being the case, it is evident that one cannot answer the question as t o whether higher intensification is profitable by conducting experiments with the class of races available today. New races can be bred which are capable of responding to a further degree of intensification. “Of old when higher intensification took place, varieties adapted to it sprang up, as it were, of their own accord”-i. e , by the process of natural selection. But this process takes place only with “extraordinary variable and plastic local varieties ” hlodern advances are made with “pure line strains of uniform heredity and little plasticity.” We can, therefore, not be sure that varieties suited to higher intensification will emerge of their own accord. Furthermore, the process of natural selection is entirely too slow. However, by crossing, multiform and very plastic starting material is provided. These crossing mixtures a r e submitted for a number of years t o the conditions of soil, cultivation, fertilizer treatment, and climate for which it is desired t o breed a suitable type. The process of natural selection is again given free rein. If types that are suitable for very high intensification are desired, these conditions must be provided “right from the start.” Here the difficulty begins. The plant breeder and the soil technologist underestimate each other’s capacity and progress is retarded. For example, the depth t o which the soil is worked might be considerably increased. Manure, fertilizer, and cultivation might be applied corresponding to this increased depth. But before it would pay, new races of plants might have to be bred that would respond to this technic. One of the interesting possibilities suggested, which indicates something of the usefulness of the science of plant breeding, was that of cultivating and improving the Jerusalem artichoke. Plant-breeding processes have never been applied to the inulincontaining plants. As a possible source of sugar, they possess considerable importance. They also contain a number of carbohydrates other than inulin. The plant breeder can produce a material increase in any desired carbohydrate naturally present in any plant. “But he must first know exactly what object chemical industry has in view in regard to the particular case.” For example, in the breeding of lupins two choices are presented. They can be bred with the idea of developing races that contain no poisonous or bitter qualities. But it has been discovered that the alkaloid contained in them has a value for technical purposes and that its value is such as t o pay for the cost of removing it from the seed. It may therefore be advisable to proceed in the direction of breeding races that contain even greater quantities of alkaloid. The whole matter depends upon the demand for this constituent. Other similar examples were given, such as breeding apples and potatoes for cold storage and the seeking out of early forcing varieties of vegetables. The cucumber is able t o bear fruit under a small intensity of light. Artificial light and manuring with carbon dioxide applied t o the production of this crop in glasshouse culture calls for breeding which can take advantage of the better facilities thus provided. Here again in calculating the economic potentialities we must take as the basis, not the yields of varieties hitherto employed, but those to be expected from the new races that are developed. Relatively small improvements may, when applied in a large way in practice, pile up an enormous increase in total production of any given crop. C h e m i s t r y of Intensively Treated Grassland -4 highly significant paper by H. J. Page, formerly chemist a t Rothamsted and now employed by Nitram, Limited, of London,
1115
dealt with the question of the chemistry of intensively treated grassland. The system employed in the intensification of grassland farming is that of making use of successive dressings of nitrogenous fertilizers, controlled rotational grazing, and systematic mechanical treatment of the land. Demonstrations carried out a t about eighty different centers showed that, on the average, 0.72 acre of pasture was all that was required per cow as compared with 2 or 3 acres required before. In one case the amount of milk produced per acre during a season amounted to 710 gallons. I n another case an acre of grassland produced 756 pounds of beef in a season. Chemical control a t nine British centers showed an acre production of intensively treated grassland of 379 pounds of digestible protein and 2676 pounds of starch equivalent, thus the extra amount of the latter required to do the work of grazing. A t the best of these nine centers these figures reached 557 pounds of digestible protein and 3887 pounds of starch equivalent per acre. The effect of this intensive system of grassland management is t o lengthen the grazing season both in the spring and fall, t o prevent such marked fluctuations of pasture during the season by raising the level of production, to produce a larger bulk of material, and t o improve its protein content. The chemical composition of grass depends upon its stage of growth. Grass cut repeatedly throughout the season has a composition closely resembling that of a concentrate. At Cambridge the average percentage of crude protein in young grass was found to be 25.03 as compared with 28.3 in linseed cake. Nitrogenous fertilizers not only increase the protein content of the glass, but very considerably increase the quantity of grass as well. This improved quality and increased quantity was maintained throughout the season. Of equal importance in many ways is the fact that the intensive system of management, employing regularly phosphate, potash, and lime treatments as well as nitrogenous top-dressings provides grass that is also very high in its mineral content. The phosphoric acid content remained a t a nearly constant level of about 1 per cent. The lime content was subject t o greater fluctuation from place t o place and from month to month. Considering Kellner’s and Henneberg’s estimates of 0.233 and 0.164 pound as being the amounts of lime and phosphoric acid, respectively, required daily by a cow giving 3 gallons of milk, it was found that these requirements were more than fulfilled in the case of phosphoric acid and just fulfilled in the case of lime. Contrary t o what was originally expected, nitrogenous fertilizers do not reduce the percentage of clover in the pasture mixtures. Close grazing prevents shading. It appears that shading is usually the cause of clover disappearance when grass is allowed to grow to some height. Another interesting feature is the fact that the supplementary ration for nitrogen-fertilized pastures is not protein concentrates but those which are high in their carbohydrate content. A full realization of the value of the pasture cannot be secured until means of keeping the ration in proper balance have been worked out. Comparison of Ammoniacal a n d N i t r a t e Nitrogen as Fertilizers A. Demolon, inspector general of thestation a t Laboratoires du Ministere de 1’Agriculture of France, gave an interesting survey of the problem of determining the comparative effectiveness of ammoniacal and nitrate nitrogen as fertilizers. While the efficiency of ammoniacal nitrogen in terms of nitrate nitrogen is usually set at 90, in some cases it is lower than this, in others the effects of the two are equal, and in still others the efficiency of ammonia fertilizers is more than 100. This coefficient varies with the crop, the method of application of the fertilizer, the amount of nitrogen applied, and the nature of the soil. It has been demonstrated that plants are able t o assimilate ammoniacal nitrogen directly. If it be assumed that the two
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I N D U S T R I A L A N D ENGINEERING CHEMISTRY
forms are equivalent for nutritional purposes, this does not guarantee that they will produce equal effects when applied to the soil. The soil hqs certain absorptive effects on ammonia which reduce its mobility. Furthermore, consideration must also be given to the other ions and elements that are introduced in association with the ammonium and nitrate radicals, respectively. A series of experimental tests as carried out in which ammonia salts and nitrates were in part competitors and in part associates. I n these tests nitrate nitrogen was usually somewhat more effective than ammoniacal nitrogen, but a mixture of the two forms gave crop increases that were greater than would be expected from the results secured by separate tests of the two. I n concluding his remarks, Demolon pointed out that French investigations of this problem indicated the general superiority of nitrate nitrogen for sugar beets, maize, and turnips, but not for potatoes and tobacco. For cereals the effects of the two were much the same. Crops growing best on soils that are neutral or slightly alkaline use nitrate nitrogen to better advantage, while those which are adapted to acid soils respond best t o ammonia salts. For crops requiring nitrate nitrogen, the slowing down of the process of nitrification by drought prevents the utilization of ammonia salts. Under such conditions nitrate nitrogen, both because of its form and ability may have a special function to perform.
Irrigation a n d Liming in Relation t o Use of Nitrogenous Fertilizers
J. Galland, agricultural engineer of Paris, presented a paper on irrigation and liming in relation to the use of nitrogenous fertilizers. The mobility of nitrates is such that following periods of heavy rainfall they may be carried below the reach of the roots of plants. If this happens t o be at a time of critical need of nitrogen by the plant, nitrogen starvation may result if only nitrate nitrogen has been applied. Recalling some data of Wilfarth’s, Galland showed that increasing quantities of nitrogen reduced the water requirement of sugar beets from 569, when 0.42 gram of nitrogen was applied, to 383, when nine times as much nitrogen had been used. Irrigation makes it possible t o use ammoniacal salts where without irrigation only nitrates can be employed. Under irrigation, the former may even be superior. Irrigation also changes the time of application of nitrogen fertilizers, delaying that of ammonia salts. Losses by leaching are much reduced if ammonia salts are employed. Under conditions of irrigation, earlier growth of alfalfa can be secured by the use of nitrogen fertilizers, in conjunction with phosphoric acid and potash. I n connection with the use of lime, Galland pointed out that it was not logical to ban the use of ammoniacal fertilizers simply because they tend to make the soil acid. It happens that, while some plants grow best in soils having a pH value greater than 7sugar beets, for example-others prefer a slightly acid soil. BY proper adjustment of acid fertilizers and lime, better results can be secured than if only the alkaline salts are available. Attempts to produce fertilizers containing both lime and ammoniacal salts did not seem a satisfactory answer t o this problem since some plants do not require the addition of the lime.
Fertilizer Problems of I n d i a A suggestive paper was presented by T. H. J. Carroll, assistant director of Agricultural Research of Nitram, Limited, of London. This dealt with fertilizer problems of India and prospects as to fertilizer consumption in that country. Poverty and ignorance both stand in the way of rapid increase in consumption of fertilizers in India. In addition, it is recognized that much investigational work must be done before sufficient information is a t hand as to how to use fertilizers under the great variety of climatic conditions that obtain. It was pointed out that under conditions of drought, small
Vol. 20, No. 10
applications, repeated a t intervals depending upon the weather, are better than single heavy applications. On the other hand, fertilizers properly used “may sometimes be equivalent to a shower of rain,” since less water is required to produce a pound of dry matter when the crop is well fed. Adequate use of fertilizers may reduce the number of irrigations required. They may serve in part as substitutes for organic manures of which the supply is limited. In general, ammonia salts give better results than nitrates in India. This is true for cotton, sugar cane, rice and tobacco, although in some cases nitrates are preferred for the tobacco. There is reason to believe that concentrated fertilizers, such as ammonium phosphate, have certain economic and crop advantages in India. The evidence in favor of including potash in the fertilizer in India is, according to Carroll, still wanting, although trials are being made with various potash salts in the belief that they may prove helpful in aiding the plant to resist disease and t o prolong its period of vegetative growth. The potentialities of fertilizer consumption in India are enormous. About 250 million acres of land are under cultivation with a possible ultimate consumption of 2 million tons or more of pure nitrogen per year. The problem is one of the ability of the nitrogen industry to supply this element to the farmers a t a price that permits of an economic return, assuming that these farmers can be induced t o follow the practices which experiment station results suggest to be feasible. Concentrated Nitric Acid by A m m o n i a Oxidation u n d e r
Pressure
A technical paper of considerable interest to the producers of nitric acid was read by G. Fauser, engineer of “Montecatini,” SocietO Generale per 1’Industria Mineraria ed Agricola of Milano, Italy. This paper dealt with the production of concentrated nitric acid by the oxidation of ammonia under pressure. It was shown that the rate of oxidation increases very rapidly with an increase in pressure and that absorption is much more readily accomplished with the result that the volume of the absorptions towers can be very materially reduced.
Extension of Tariff on Chemicals in Britain Further extension of the British import duty t o a considerable range of chemicals and allied products is considered likely as the result of the recent decision, which went into effect June 4, making calcium biphosphate of baking powder quality dutiable a t 33.5 per cent, according t o information received a t the Department of Commerce. The finance act places a tax on light hydrocarbon oils, including turpentine, and affects materials entering into the manufacture of various chemical and allied products, such as paints and varnishes, polishes, synthetic camphor, and terpineol, as well as the rubber and other industries. The decision making calcium biphosphate of baking powder quality dutiable a t 33.5 per cent, under the Safeguarding of Industries Act, upon importation into the United Kingdom, was the most conspicuous of the official decisions recently made. Additions to the list of chemicals exempted from duty until the end of the year, however, have been made: among others, lactic acid, metaldehyde, and methyl chloride.
Correction In the article entitled “Abrasion Tests of Rubber Stocks-Containing Various Types of Carbon Black,” by W. B. Plummer and D. J. Beaver, on page 895 of the September, 1928, issue the formula used in Series 2 was omitted from Table I1 on page 897. The formula for this series of compounds was 100 pale crepe, 5 zinc oxide, 4 sulfur, 1 stearic acid, 0.75 D. P. G., 25 black, by weight.
