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of t h e m e r c u r y i n t h e p i p e t t e a n d t h a t i n t h e level B y m o v i n g t h e p o i n t of s u p p o r t of t h e s p r i n g o n b u l b . This is ordinarily a c c o m p l i s h e d b y resting t h e lever a r m i t c a n b e so a d j u s t e d t h a t t h e vertical t h e level b u l b o n a pile of blocks which c a n b e r e m o v e d distance t h r o u g h which t h e p a n m o v e s , w h e n t h e s p r i n g or a d d e d t o a s m a y b e necessary. B u t t h e s e blocks is deflected, i s j u s t e q u a l t o t h e h e i g h t of t h e c o l u m n a r e i n c o n v e n i e n t a n d usually t h e y a r e t h i c k e n o u g h of m e r c u r y which h a s left t h e p i p e t t e i n order t o p r o d u c e t o cause considerable difference i n t h e level of t h e t h i s deflection. m e r c u r y . F u r t h e r m o r e , t h e a b r u p t c h a n g i n g of t h e T h e principle is rendered clearer if o n e considers pressure m a y cause l e a k a g e i n t h e r u b b e r connections t h e level b o t t l e s u s p e n d e d directly o n a spring. A a n d m a y l e a d t o explosions i n cases w h e r e t h e r a p i d u n i t weight of m e r c u r y p r o d u c e s a n elongation of lowering of t h e pressure i n t h e p i p e t t e d u r i n g t h e progt h e s p r i n g which is j u s t e q u a l t o t h e height of t h i s ress of a c o m b u s t i o n causes t h e g a s t o e n t e r t h e p i p e t t e ’ a m o u n t of m e r c u r y w h e n i t is confined i n t h e p i p e t t e . too rapidly. T h u s t h e level of t h e m e r c u r y is a u t o m a t i c a l l y k e p t T h e following a p p a r a t u s is designed t o o v e r c o m e constant during t h e entire combustion. t h e s e difficulties b y m a i n t a i n i n g a c o n s t a n t level of T h e a b o v e f o r m of t h e a p p a r a t u s was designed i n t h e mercury during t h e combustion, t h u s insuring o r d e r t o m a k e i t possible t o use different sizes of level constant pressure. T h e device b o t t l e s a n d p i p e t t e s , a n d also t o m a k e i t easy t o reshown in t h e accompanyplace t h e spring b y o t h e r s of different s t r e n g t h s . i n g figure consists of a m e t a l E c o n o m y of space w a s a n o t h e r reason for a d o p t i n g base a n d a n u p r i g h t w h i c h t h i s f o r m . While t h i s f o r m is n o t m a t h e m a t i c a l l y s u p p o r t s parallel lever a r m s . e x a c t , a s is t h e case of t h e freely s u s p e n d e d spring, A t t h e e n d s of t h e s e a r m s is i t m a i n t a i n s a pressure which is c o n s t a n t for all p r a c a t t a c h e d a p a n which m o v e s tical purposes. T h e a p p a r a t u s c a n also b e m a d e t o vertically, b u t a l w a y s r e m a i n s m a i n t a i n a c o n s t a n t pressure e i t h e r a b o v e or below i n a horizontal position. T h e t h a t of t h e a t m o s p h e r e , b y a d j u s t i n g t h e s p r i n g as level b o t t l e is c o n n e c t e d as described before. usual w i t h t h e c o m b u s t i o n T h e principle is c a p a b l e of o t h e r applications t o p i p e t t e b y m e a n s of r u b b e r a p p a r a t u s for handling a n d m e a s u r i n g gases. t u b i n g a n d i t is placed u p o n T h e a p p a r a t u s is m a n u f a c t u r e d b y Greiner a n d t h e p a n . A coil s p r i n g is sus- Friedrichs, S t u t z e r b a c h i n T h u r i n g e n , G e r m a n y , a n d p e n d e d f r o m t h e u p p e r p a r t of t h e f r a m e w o r k a n d is k n o w n a s t h e “ G i l b e r t M a n o s t a t . ” is a t t a c h e d t o a n a d j u s t a b l e point o n t h e lever a r m . CORNELL UNIVERSITY,I T H A C A , h’Ew Y O R g
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ADDRESSES
T H E EXCESSIVE QUANTITIES OF NITRATES IN CERTAIN COLORADO SOILS By W x . P. HEADDEN Received April 21, 1914
The Colorado Experiment Station has issued, up to the present time, eight publications1 pertaining to the occurrence and origin of excessive quantities of nitrates in certain soils. These remarkable occurrences were first definitely recognized about r g o j . The difficulty of accounting for the nitrogen necessary to form these nitrates presented itself from the very first, but no other theory than the fixation of atmospheric nitrogen seemed available and adequate. The above mentioned publications report the occurrence and distribution of the nitrates and their effects upon vegetation, particularly upon apple trees, but also upon the quality of sugar beets. The source of these nitrates is sought in the activity of the bacterial flora of the soils. This view is urged on the ground that there is no known source from which the nitrates may be derived ready formed. The distribution of the nitrates is such as to preclude their derivation from any system of rocks, and they are so widely distributed that some generally prevailing condition must be operative in their production. The direct evidence adduced consists of a series of consistent facts which support this contention; i. e . , these soils have been shown, by direct experiment, to fix nitrogen in a marked degree, and also to change it into nitric acid (nitrates) very much more energetically than do eastern, southern and foreign soils in general. The fixation is attributed to the azotobacter which are found t o
* Bulls. 166, 160, 178, 183 and 186, b y Wm. P. Headden; 179 and 193, by Walter G. Sacliett; 184, b y Walter G . Sackett and W. W. Robbins.
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occur in these soils in great abundance, and whose characteristic pigment constitutes the first most striking character of these niter-areas. The appearance of this color has been recognized very generally by the orchardists and ranchmen as the beginning of serious trouble. It is related throughout these publications that complaints were made t h a t the land turned brown and then the trees died, or that nothing would grow. The very first occurrences examined had been mistaken as exudations of oil. The surface of the ground was black and glistening. The areas involved were small and nearly circular. An analysis of the surface soil showed the presence of 13.4per cent of water-soluble material, of which nearly 42.0 per cent consisted of nitrates. These were largely the calcic and magnesic salts. There was a number of such brown areas, mostly smaller than the one referred to, in this locality. That such areas should be destitute of vegetation would seem a natural and even necessary result of the presence of such quantities of nitrates, in this case j.6 per cent of the air-dried soil. Other and larger areas were observed, which were either devoid of vegetation, or on which the vegetation was suffering without the presence of any evident cause. Examination of such cases showed the presence of unduly large amounts of nitrates. These facts enlarged the question from one of scientific curiosity t o one of very great agricultural importance. Individual orchardists had, in the meantime, taken cognizance of the fact that this was a serious trouble and that there was an intimate connection between the turning brown of the soil and the death of the vegetation, whether orchard trees, alfalfa or vegetables. Complaints of “brown-spots on which nothing will grow” became quite numerous and pointed the way t o new localities for these
T H E JOCRiVAL O F INDL'STRIAL A N D E N G I N E E R I N G CHEMISTRY occurrences. More than thirty cases are presented in detail to establish the fact of the occurrences of nitrates in these soils, and t o give the conditions under which they occur, together with their distribution throughout the State. In regard t o the quantities of nitrates present, they are shown to vary from a few tenths of one per cent t o upwards of six per cent of the air-dried soil. The areas involved vary from a few square feet t o many acres in a single body. The distribuiion of these areas is practically throughout the cultivated sections of the State, but they are much more common in some sections than in others. EFFECT OF KITRATES ON TREES
'6444.5 p. p. m. nitric nitrogen, while a sample taken twenty feet from this, but outside of the brown spot, carried 43 j.2 p. p. m. total and 2.0 p. p. m. nitric nitrogen; the soil was not wet in either place. I n another case the brown spot contained 8,500 p. p . m. total and 7,077 p. p. m. nitric nitrogen while the ordinary soil sixteen feet from the edge of i t carried 591.6 p. p. m. total and 16.0 p. p. m. nitric nitrogen. The brown color is characteristic of these spots and also of old azotobacter colonies. The excessive nitrogen in the soil, especially the excessive nitric nitrogen, is very definitely indicated by the color of the surface soil, and in cases in which the accumulation of nitrates is not too great these soils teem with azotobacter.
These occurrences of' nitrates were not always present in the NITRATES AND COMPOSITION OF SUGAR BEETS localities where they are now found. While some of them were known eighteen and twenty years ago, their real nature was These occurrences are looked upon as exaggerated instances unknown, and they did not become very prevalent till 1908 or of a general condition frequently prevailing in Colorado soil. It is cited as a fact that the quality of the sugar beets grown in 1909 when their effects became so pronounced that they could not be overlooked. These results were disastrous and very the Arkansas Valley from 1893 to 1904 averaged 17.5 per cent noticeable because in 1909 apple trees began t o succumb-at sugar and worked easily in the factory, but from 1904 till 1911 first a few trees here and there, two, four or a dozen-but this the beets averaged much lower in sugar, 14.2 per cent in 1910, was rapidly followed by the dying of hundreds in a body, taking, and worked very badly, yielding as high as 9.5 per cent molasses. During this period there were some excellent beets produced in some cases, the whole of small orchards. The cause seemed evident, but had to be proved, which was done by the application every year, but not enough to maintain the average abore the of sodium nitrate t o comparatively small trees, four-year-old figure given. The fact t h a t fields of most excellent beets, containing 18-23 per cent sugar, were produced annually throughout ones, when i t was found that all the changes observed in the affected trees were reproduced by the nitrate, even t o the killing the \'alley was taken as a refutation of the frequently made claim of the trees. As no data were at hand showing the effects of that it was all due t o climatic conditions. The low general sodium chloride on trees, this too was tried, because this salt average for the sugar content, the bad working qualities, and the is sometimes, but not a t all often, present in considerable quanti- large percentage of molasses produced were interpreted as indities in Colorado soils. Sodium chloride did not produce any of cating some prevalent soil condition which produced this effect. the phenomena observed in the orchards. These results were The prevalent soil condition was believed to be the presence of so conclusive in regard to the cause of the death of the apple too large a supply of nitric nitrogen, i.e . , nitrates, duringtheseason. trees, t h a t no reasonable doubt remained in regard to it. The The whole subject of the deterioration of the quality of these sugar beginning of this serious feature is given as 1908 or 1909. It beets is considered as an illustration of a general effect upon a crop continued t o spread and to increase in virulence until in 1910 due t o an excessive supply of nitrates furnished by the soil itself. Some of the more specific facts adduced in this connection are and 1911 it was so prevalent that the area actually treated of in Bull. 178 is given as four hundred acres and the'affected area as that the beets grown in this Valley contain high percentages of from three to four hundred square miles. I n one district, including nitric nitrogen, or nitrates. It is shown that some samples about fifty square miles, the orchards have been ruined, at least of very poor beets carry from 0.13 t o 0.6 per cent of nitrates calculated as potassic nitrate, whereas the best beets analyzed practically so, as very few healthy orchards survive. h-o statement is anywhere made indicating the minimum contain none. The molasses produced contained large amounts amount of nitrates capable of injuriously affecting apple trees of nitric nitrogen, from 0 . 1 2 to 0.47 per cent, or from 8.64to or other vegetation; it is merely shown that the application of 33.84 per cent of nitrates calculated as potassium nitrate, as five pounds of nitrate, sodium nitrate, to a four-year-old tree compared with 0.046 per cent of potassium nitrate in the best produced some injury. On the other hand, it is shown that the Bohemian molasses analyzed. Starting from these facts and guided by previous field cbserspread of the roots of a medium sized apple tree is not less than forty feet and that in many cases the nitrates occurring within vations, a study of the effects of nitrates upon the compcsition a radius of twenty feet of the tree trunk amount to as much as of the sugar beet and its working qualities established the fact several hundred pounds, quantities very much in excess of those t h a t the composition of beets grown with the application of experimented with and which sufficed to do injury to, and even sodium nitrate in excessive quantity was just such as was actually , found for the general crop including the low percentage of sugar, t o kill, the trees. The progress of the injury to orchards is shown t6 be re- i. e., the presence of nitrates in the beets, the watery-white, markably rapid. -%ti instance is given in which the injury brittle flesh, and the production of thick juices having a low began t o become evident in May and by -4ugust about two coefficient of purity. acres of the orchard had been killed; by the end of .Sovember, The poor quality of the beets during the period mentioned nearly three acres and within a year thirteen acres were in such had often been attributed to the attacks of the fungus Cercospora bad condition as'to be of little or no value. This land had become beticola, or leaf-spot. The attacks of this fungus were so severe mealy and then brown and the amount of nitrates formed and and general that i t had t o be considered. The foliage cn whole brought into the feeding areas of the roots passed the danger fields of beets had often been practically destroyed. In the point and the trees died. absence of any data to show that any further injury than that The amount of total nitrogen present in the brown spots is, of defoliation is ever produced by this fungus, the effects of total as a rule, larger than is commonly present in Colorado soils defoliation were studied. I t was found that total defoliation which does not usually &xed 0.10per cent, and is furthermore as late as September 6th, profoundly affected the composition largely present in the form of nitric nitrogen. It is not uncomand total crop of beets. The changes produced in these beets, mon to find the nitric nitrogen equal t o from 15 per cent up to however, were almost entirely different in kind and degree from even 90 per cent of the total nitrogen. The contrast between those produced by the application of nitrates. These latter the amount of both total and nitric nitrogen in the brown spots changes were much more profound than had been indicated as and the ordinary soil is often very great. An example is given probable by a study of the beets from 1 2 7 fields where the fungus in which the brown spot contained 6629.6 p. p. m. total, and attacks varied in virulence from very light t o the almost total
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destruction of the leaves, The chief points which it was endeavored t o establish, were: (I) Are the changes produced in the composition of the beets by defoliation, whether by knife or leaf-spot, identical in character with those found in the deteriorated crop? (2) Are the changes the same as those produced by the application of large quantities of nitrates? It was found that both defoliation and nitrates produce great changes in the beets and their qualities, but t h a t the beets grown with the application of nitrates show those changes which were found in the deteriorated crops, while the defoliated beets do not. A widely distributed and uniform cause is inferred as producing these results, the immediate expression of which is the presence of nitrates in excessive quantities or at a time when they seriously affect the quality of the crop. The occurrence of very large, exceptionally large quantities of nitrates has been established by direct observation in many localities and by a large number of analyses. The effects of such excessive quantities of nitrates upon apple and other trees, and vegetation in general, have been observed in many localities, and the sufficiency of the nitrates to produce the effects observed in the case of apple trees established by direct experiments made o n young trees. The general and more diffused effects, as well as the wide distribution of the cause itself, have been established by a study of sugar beets, their composition and characteristic deportment in the preparation of sugar from them. The problem just stated presented considerable difficulties because of the many factors’ involved, the most patent of which may be enumerated as the part played by: ( I ) excessive salts in the soil, i. e., alkalis; ( 2 ) excessive water and seepage (generally associated); ( 3 ) the effects of various plant diseases, e. g.. leafspot; (4) insect injuries; and ( 5 ) all of the various effects suggested by t h a t comprehensive term “climatic conditions.” A previous study of the effects of the first two, extending over a period of four years, led to the conclusion that these factors may well be completely eliminated, so far as the questions here presented are concerned. The effects of the leaf-spot have been specifically studied in this connection, and while its seriousness is in no way minimized, it is not considered as the cause of the specific deterioration. Those factors signified by the term “climatic conditions” are in part recognized, b u t the most of them are considered as too general t o admit of definite study under such a designation. Hail, in one case ’was practically fatal t o a crop while in another its effects were inappreciable; the influences of dry weather, hot winds, early or late frosts, etc., were also considered. Conditions for their study were most favorable during the whole of its progress which extended over three seasons. EFFECTS OF COMMON FERTILIZERS Still other factors which had t o be considered pertained t o the soil, its mechanical, and especially its chemical properties; also its supply of plant food, and the ratio of the respective nutrients t o one another. These influences could not be studied satisfactorily by any analytical method, therefore experiments t o determine the effects of the common so-called plant foods, singly and in a variety of combinations, were depended upon for information. Analyses showed an abundance of calcium, magnesium, potassium and phosphorus, together with a fair amount of nitrogen. The plant foods added in the experiments were stockyard manure, calcium as burnt lime and as factory waste lime (which contains both phosphorus and nitrogen) ; nitrogen as sodium nitrate, phosphorus as superphosphate, and potassium as sulfate or muriate. The results were concordant with previous observations made on the effects of fertilizers applied to Colorado soils, i. e., they produced no marked results, such as would reward one for applying them, and what was more significant, no one of them effected so definite a n improvement in the quality of the beets as t o be unquestionable, or even t o indicate a probable line of experimentation for the betterment
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of the quality of the crop. I n one series of experiments the addition of 250 pounds of sodium nitrate per acre increased the crop and improved the quality. All quantities in excess of 250 pounds per acre lowered the yield and depressed the quality. I n these fifty odd experiments, just referred to, not a single positively beneficial result was obtained. It was concluded t h a t there was no lack of available plant food and no disadvantageous ratio which was corrected by any fertilizer or mixture of fertilizers used. Of the elements in question in this connection, potassium and phosphorus are not variable from time t o time, b u t the nitrates have long been known t o be. There are portions of the land on which these experiments were made in which very excessive quantities of nitrates develop a t times. The assumption is tacitly made, though not stated with definiteness, t h a t the disturbing factor in these experiments was the formation of a sufficient quantity of nitrates during the season t o eliminate the differences which one would expect t o be produced by the various mixtures of fertilizers applied, so that the result was the production of very uniformly poor beets. These experiments extended over two years and the results are concordant with those obtained in other experiments. It is stated as a general proposition that the Colorado soils are only moderately well supplied with nitrogen, the average being 0 . 1 0 per cent. On the other hand, it is also stated Gat nitrogen-hunger has not yet been observed; on the contrary there is everywhere evidence of an ample supply, often positive evidence of a n excess, though not to the extent of causing injurious effects, such as the burning and killing of plants. In this connection emphasis is constantly laid upon the high ratio of nitric nitrogen to the total, quite frequently reaching the high figure of 50.0 per cent, or even higher, while the usual maximum for this ratio is given as 5.0 per cent. The amounts of nitric nitrogen which occur in many places, involving large areas, where orchards and other vegetation have been injured or killed outright, have already been given, but the quantities occurring in cultivated lands, apparently in good condition, but which produce sugar beet crops of poor quality were.also studied and compared with those in other soils. The maximum amount of nitric nitrogen occurring in ordinary soils is assumed not t o exceed 8 p. p. m. The average amount found in 71 samples of a Fort Collins soil taken t o depths of z and 3 inches, October 4-8, was 6 p. p. m.; of 28 samples taken.from the third t o the sixth inch inclusive, was 5 p. p. m. The average of 46 samples taken to a depth of 6 inches from different beet fields, October 1-15, was 2 0 p. p. m.; from 5 4 other beet fields, also taken t o a depth of 6 ’nches, January 26-31, was 13 p. p. m. The abundance of nitrates in some of these samples does not appear at all when the results are given as averages which merely show t h a t the first 46 fields sampled contained, in early October, 2 . 5 times as much nitric nitrogen as is usually considered a maximum quantity. Among these 46 samples is a maximum of 160 p. p. m. or twenty times the usual maximum. Others contain 70, 80, IOO and 1 2 0 p. p. m., respectively, and among the 5 4 samples taken in January, a maximum of 140 p. p. m. occurs. SODIUM NITRATE APPLIED TO SOILS I n the experiments with sodium nitrate i t was’ found t h a t all quantities in excess of 2 5 0 pounds per acre produced beets showing the qualities of the crops of deteriorated beets. The time of application or occurrence of the nitrates is evidently of considerable importance, but leaving this out of consideration, the general result was that the deterioration in the beets increased with the increase of the amount of n’itrates added till 1000 pounds per acre was reached, which produced the maximum depression in the quality of the crop obtained. This maximum depression may be indicated by the percentage of sugar, which was depressed from 1 6 . 5 t o 1 1 . 0 per cent, or 5.5 per cent of the beets, and the ratio of proteid t o the total nitrogen which was reduced from‘31 t o 1 6 . 5 . This is a reduction of 43 per cent in
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this ratio, but the ratio of 31 is only a little more than 60 per cent of that of very good beets. The average amount of nitric nitrogen found in the surface 6 inches of these 46 fields corresponded to the presence of 480 pounds of sodium nitrate per acre while the 160 p. p. m. corresponded t o about 1440 pounds. This quantity, however, is still very far from the maximum found in beet fields by systematic sampling. A certain field was chosen and divided into eight sections and sampled seven times during the season. The first samples were taken March 4, and the last August 25. During this period the respective sections into which the field was divided varied greatly in their content of nitric nitrogen not only among themselves but from date t o date of sampling. The maximum variation in any one section was from 6.5 to 333 p. p. m.; another varied from 4.1 t o 2 5 1 p. p. m.; the beets from,this field were poor in quality, 12.6per cent sugar. Another field sampled in like manner showed 130 p. p. m. as the maximum with the next highest sample, 67 p. p. m., but the nitrates throughout the season were low. The samples taken August 2 5 ranged from 2 . j t o 1 2 . 0 p. p. m. and the beets were good-17 per cent sugar. The samples last referred t o were taken to a depth of one foot, and gave a maximum of nitric nitrogen corresponding t o approximately 8000 pounds of sodium nitrate for the surface acre-foot. The question of the origin of these nitrates has been kept in view from the beginning of the work. The presence of the nitrates in many of the Colorado soils in very extraordinary quantities cannot be doubted, neither can it be doubted t h a t the brown-spots with their remarkably large quantities of nitrates are exceptional manifestations of a condition t h a t is met with over large areas and constitutes an important factor in the agriculture of the State. '
WATERS NGT SOURCE OF NITRATES
The first source considered for the nitrates occurring in the brown-spots is a concentration of previously formed nitrates, but this is regarded as inadequate. Some of these spots are described as occurring isolated, or in isolated groups, on soils of lacustrine origin surrounded by granites and mica schists while the deeper waters are of very high purity and acid in quality, The surface waters are, as a rule, charged more or less heavily with the ordmary alkalis of the section, which consist of the sulfates of calcium, magnesium and sodium with relatively small amounts of chloride and carbonates. There is one exception to the absence of carbonates from the deeper waters. Kitrates are ahsent except in such quantities as may be found in waters generally, even in waters entirely free from contamination. The nitrate spots are not points of issue for underground waters. Further, the spots occur on mesas or small plateaus where there are no other streams than irrigating ditches. These irrigating ditches, with no important exceptions, carry water furnished by mountain streams, and such waters have not been found to carry nitrates. The ground waters of many sections of these districts have been examined and found free from nitrates, except in cases where the waters were taken from beneath areas the surfaces of which were rich in nitrates. Drain waters from alkalized areas were also free from nitrates, unless the drains passed beneath nitrated areas. The alkalis, soils and ground waters occurring on or in lands adjacent t o and higher than some niter spots, were examined in detail and no nitrates beyond traces were found, while samples of soil taken to a depth of one foot from the area discussed, showed the presence of two and a quarter tons per acre. This process of elimination of sources sufficient to explain satisfactorily the occurrence of these nitre-spots led t o the rejection of the concentration theory. There was no question.about the presence of the nitrates in sharply defined areas with no apparent and adequate source of the nitrates. Many of these spots occurred on well drained land and the water t h a t flowed from the higher lands in the gravel underlying these general sections contained only 0 .I O L
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p. p. m. of nitric nitrogen. The soils in general do not contain a large supply of nitrogen from which nitrate may be formed; their nitrogen content averages about 0.10 per cent. If this nitrogen were all nitrifiable and were nitrified practically a t one time and converted into sodium nitrate it would give only about 0.60per cent of this salt in the air-dried soil, whereas the brown-spots often contain very much more, so that the question relative to the source of the nitrogen became an insistent one. It seemed evident that as the soils themselves contained a n inadequate supply for the formation of the nitrates found, and these nitrates did not exist ready formed in the alkalis and ground waters of adjacent lands, there was only one other adequate source and that was the atmosphere. But ordinary soil has no marked power, even when alkaline in reaction, to bring about the oxidation of atmospheric nitrogen either directly or indirectly. Certain soils may, as has been suggested, bring this about in a small measure, but not in such a marked degree as is presented in these spots. Some agent was sought which is capable of transferring the atmospheric nitrogen to the soil in some easily nitrifiable form. The predication of some such agent was considered as the only reasonable explanation for the facts, because in the beginning these spots were sharply defined and characterized by a brown color and a n abundance of nitrates. While the limits of these spots were most sharply defined, they were not fixed; on the contrary, they often extended rapidly. The brown color and remarkable quantities of nitrates were always associated. This excessive development was a local one which extended its boundaries and was characterized by the presence of a brown color. These considerations led to the adoption of the theory of fixation, due to microorganisms. The azotobacter were known t o be able t o appropriate the atmospheric nitrogen in the building of the proteid material of their own bodies. Some of them, a t least, were also known t o form brown pigments. Given the presence of such organisms, the brown color of the spots was easily explicable, and with i t the source of the excessive nitrogen, i. e., the atmosphere, through the agency of these azotobacter. The presence of these organisms would account for the nitrogen and the color, but not for the final form of the nitrogen, i. e . , as nitrates. This transformation, however, is very rapidly brought about by other organisms. It was tentatively held t h a t the azotobacter themselves effected this transformation, but this view was abandoned, because the reactions on which it was based were subsequently found t o be due t o the pigments formed by the azotobacter and not to nitrates.' It has quite recently been held by Mr. Dan H. Jones,* that the azotobacter form nitrates in their body tissues. If this were correct it might contribute materially in accounting for the formation of these nitrates. The reactions obtained by Mr. Jones, however, were very probably due to pigments and not t o nitrates. These soils were tested and it was found by experiments that they possessed, in a high degree, the power to fix nitrogen, and that this power is limited only by those conditions obtaining in the soils which limit the growth of the azotobacter themselves. It was also shown that these soils possess a very high power of nitrification. The bacteriological and cognate features are treated of in Bulls. 179 and 193, by Professor Sackett and in Bull. 184, by Sackett and Robbins. Investigation of the soils from these standpoints developed the fact that all of the soils in question gave rise to remarkable developments of azotobacter, heavy films being obtained in a few days. Further, pure cultures of these bacteria fixed notable quantities of nitrogen and produced pigments freely. Some samples collected from the surface of 1 T h e reaction of these pigments with phenolsulfonic acid render this reagent altogether unfit for t h e estimation of nitric nitrogen in some soils. Large quantities of t h e pigments give, with this reagent, a deep brown color which on sufficient dilution appears yellow with a tinge of hrowiAvery easily mistaken for the nitric acid reaction. 2 Trans. R o y . Sac. Can., 3 (1913). Sec. 4.
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the interior of these brown-spots failed to give a development of azotobacter, but samples from the deeper portions of them showed that the azotobacter were still living. They had merely been killed off in the upper portions. The azotobacter-flora of these spots were found to be abundant, and the high nitrogenfixing power of such soils was reasonably explained. No definite attempt to account for the energy needed for the growth of the azotobacter was made. It was simply stated that some of the samples of soil preserved in a moist chamber in the light developed an abundant growth of algae, and this was suggested as a possible source of energy. The ammonifying power and algal flora of some of these soils were subsequently studied by Sackett and Robbins. The results showed t h a t these nitrate soils possessed a very much higher ammonifying power than the ordinary Colorado soilstwo, and in some cases, three times as much. Colorado soils compared with soils from New Jersey, North Carolina, California and Iowa, exceed them in ammonifying power from one and onehalf t o eight times, except in cases in which lime had been added to a New Jersey soil. The results of the study of the algal flora present in the samples examined showed the presence of twentyone different species of algae, nineteen of which belong t o the Cyanophyceae. A few not present in the samples examined in this study have since been met with in other samples. A few samples of raw adobe soil have been found to be devoid of a n algal flora and also of any power of fixation. The subsoils in some of the good cultivated lands are well provided with algal spores, probably through the instrumentality of earthworms, for they develop a strong growth of algae when exposed to sunlight in a moist chamber. The last step taken in this work pertains to the nitrifying power of these soils. Experiments were made with samples of these soils early in the progress of this work in which gains in nitric nitrogen ranging from 19 per cent of the nitric nitrogen present a t the beginning of the experiment to 138 per cent were recorded. The former figure, 19 per cent, was obtained in the original sample kept in the laboratory in its natural, moist condition; the 138 per cent gain was obtained on incubation at 28' C. for 48 days. A systematic study of this subject by Professor Sackett has been but recently completed. The results show that these Colorado soils have a high nitrifying power, especially for ammonic sulfate and carbonate. I n comparison with foreign soils, i. e . , soils from other States, the Colorado soils have a far superior nitrifying power; e . g., the average net gain of the positively reacting Colorado samples in the presence of ammonium sulfate was 672 p. p. m. of nitric nitrogen, while t h a t of the foreign samples was 151 p. p. m. With ammonium carbonate the average net gain for the Colorado samples was 52 I p. p. m., and for the foreign samples 215 p. p. m.; with dried blood this gain was for Colorado samples 432 p. p. m. and for the foreign samples 267 p. p. m. The significance of these results, showing the superiority of the Colorado samples over the foreign samples in nitrifying power, cannot be interpreted in any other way than as strongly supporting the views previously advanced. The series of facts so far established seem conclusive in establishing the correctness of the view that the occurrence of these unusual quantities of nitrates in the Colorado soils is primarily due to fixation of atmospheric nitrogen by azotobacter. It is held t h a t these conditions suggest an explanation for the formation of the Chile-saltpeter beds, but the economic beneficiation of these soils as a source of nitrates t o be used as a fertilizer is held t o be wholly impracticable. SUMMARY
The basal facts in these investigations are: I-The presence of very large amounts of nitrates in certain areas. a-These areas are characterized by a brown color.
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3-The quantity of nitrates in the areas is frequently sufficient t o exterminate all vegetation and render the land barren 4-The identity of the action of sodium nitrate upon apple trees with the action of the salts in these areas was established by direct experiment. 5-The general distribution of this occurrence has been recognized by its effects upon the composition and qualities of the sugar beet crop 6-It has been established by extended field experiments that the composition and character of these crops are identical with those produced by the application of Chile saltpeter. 7-It has been shown that any theory of concentration of previously existing, ready formed nitrates by the agency of water is not adequate to explain the facts found, as the nitrates do not exist in the alkalis, soils or waters of these sections. 8-It has been established t h a t these soils possess a high nitrogen fixing power. 9-Azotobacter occur very abundantly in these soils. Io-The azotobacter form a brown pigment which accounts for the characteristic color of the spots or areas. I I-The ammonifying power of these soils is very much higher than that of the ordinary soils. 12-Their nitrifying efficiency has been shown to be exceedingly high. 13-The algal flora of the soils has been found to be abundant and may furnish the energy necessary for the growth of azotobacter. STATE AGRICULTURAL COLLEGE FORT COLLIBS, COLORADO
THE WORKINGS OF THE CALIFORNIA INSECTICIDE LAW1 By GEO. P. GRAY
We have in successful operation the National and State Food and Drug laws, intended t o safeguard against fraud and imposition, the millions of human stomachs of the nation. The stomachs of domestic animals are protected in a like manner by the operation in many states of feeding-stuffs laws. Other states have been equally solicitous of the welfare of the automobile by passing oil inspection laws. Even the food of plants has not been overlcoked and is regulated by many state fertilizer laws. And lastly, but not least (certainly in respect t o the number of individuals affected), the crawling and creeping things of the earth have been the subject of National and State legislation t o insure that they shall receive their full and unadulterated measure of the potent poisons which are dealt out t o them so lavishly by the hand of man. Inasmuch as the scientific study and application of insecticides and fungicides are of very recent development and the attempt to control the materials used for that purpose by legislation dates from the year of 1898, this matter has only recently come t o the serious attention of chemists. Agricultural literature is full of information on the subject of insecticides but most of the work reported has been that of the entomologist whose training has been along other lines than chemistry. The rapid development of this line of work on a more scientific basis, the more intimate study of the action of poisons on insect and fungous life, has shown the need of chemical advice. The passage of control measures has also necessarily added t o this need, there being a t present not less than twelve states which have passed laws regulating the manufacture and sale of insecticides and fungicides and possibly other states not known t o the writer. Other states will doubtless follow. The examination of materials incident t o the administration of these laws is largely a chemical problem. This, then, has opened up no inconsiderable field for chemists and will more and 1 Presented before the California Section of the American Chemical Society, San Francisco, December 13, 1913.
