The world's consumption of fertilizers guano, MAIZIÈRES (L'Engrais, 10 (1895), No. 19, pp. 443, 444).—The following are given as the amounts of guano imported into Europe, 1889-'94:

Tennessee phosphate rocks, J. M. SAFFORD (Tennessee Bureau of Agr. Rpt. 1893-'94, pp. 211-224, fig. 1).-This article contains a somewhat popular account of the composition, characteristics, and geological relations of the Tennessee phosphates in general, with a more technical discussion of the origin of material and other theoretical considerations by the State geologist, and a note on the white phosphates of Tennessee by G. W. Hayes, of the United States Geological Survey. The phosphate rocks of Tennessee are closely associated with a persistent, approximately horizontal formation, the Black Shale or Black Slate. There are two chief beds of phosphate, one immediately above the shale, the other immediately below it.

"The phosphate beds are, geologically, a thousand feet below the lowest of the coal beds. This shows that Tennessee phosphates are very different in age from the beds of South Carolina and Florida. The latter are far younger than the coal, and are, indeed, among the latest of geological formations.

"The rocks of the limestone floor are, in the language of geologists, of Silurian age. The formations above the Black Shale group are sub-Carboniferous; or, in later language, Mississippian. Sandwiched between these, or say, between the limestone floor and the Harpeth Shale, lie, in comparatively thin layers, the four members of the Black Shale Group."

These, commencing with the lowest, are sandstone, main phosphate bed, Black Shale, and kidney phosphate.

"The main phosphate has a wide distribution. In all the counties west of the meridian of Nashville, and between that and the Tennessee River, the rock, in its proper geological horizon, is to be found. It even extends beyond the river into Decatur and Benton counties. It lies, as we have seen, below the Black Shale, and everywhere, in the region indicated, goes with it. . . . But it must not be understood that it has practical importance in all this wide territory; not by any means. As a rule, it is generally too thin or too sandy or limey to be of value. The best of it, the thickest and purest, is found in a comparatively limited area or belt of country lying chiefly in Lewis and Hickman counties."

Good workable phosphate is found throughout Swan Creek Valley in these counties, and here the most active mining operations are carried

on.

"The rock ranges from 6 to 40 in. in thickness and contains from 60 to 75 per cent of phosphate. . . . The length of the Swan Creek belt holding phosphate is 20 miles; say its width is 3 miles, then we have an area of 60 square miles. Suppose but one-third of the phosphate of this area to be available, with these liberal limitations, our belt gives us more than 123,000,000 tons."

"[The phosphate of this bed] is sometimes dark-colored and fine-grained, as if it might be compressed gunpowder. This variety oxidizes on exposure, so as to form a yellowish crust or layer, giving the rock very much the appearance of a sandstone. But it lacks the hard grit of sandstone, and this leads to its recognition.

"Then again it is light-colored, or gray, and made up chiefly of small seed-like or grain-like bodies, or of a multitude of minute spiral shells. Sometimes thin layers are met with that ring like pot-metal when thrown down or when struck with a hammer. Locally it is found thoroughly disintegrated, oxidized, whitened, and resembling clay. The coloring matter of the darker kinds is organic, derived either from plants or animals, or both. Hence such kinds oxidize and burn white, or to a much lighter color. Several species of the minute shells occur, and also worn teeth, and sometimes fragments of fish bones.

...

"The bed of Kidney Phosphate, thick, thin or in traces, is well nigh universally found in its place above the Black Shale. It is a stratum of roundish, solid, phosphatic concretions, from the size of marbles to masses as large as one's head, or to flattish, cake-like, kidney-like, gourd-like forms of larger size. At certain localities they are to be seen, with a little shale, tightly packed together, as if so many cannon balls, in a layer 8 to 12 in., or exceptionally 18 in., in thickness; or else loosely disposed and embedded in greenish shale. The latter is itself more or less phosphatic, and is quite generally found in association with the balls. . . .

"When long exposed the kidneys weather externally to a grayish or whitish coat. When broken they show a brownish gray color, with a center, often of open, granular structure, somewhat oölitic. They contain from 60 to 65 per cent of calcium phosphate, and yield an approved fertilizer. When the balls and the lower phosphate are separated by only a few inches or a foot of Black Shale they may be mined together, making it profitable, where the mining of one alone would not be."

The theoretical considerations are presented which lead to the conclusion that these deposits have been derived from the remains of fish and other marine animals deposited during the Devonian age.

Two varieties of white phosphate (1) breccia phosphate and (2) white bedded phosphate "resembling more or less closely the Florida rock" have been found in Perry County, but their content of phosphate of lime (27 to 33 per cent) is too low for them to be of much commercial importance.

The marls and phosphates of North Carolina, F. B. CARPENTER (North Carolina Sta. Bul. 110, pp. 455-504, map 1).-A summary of information on the location and extent of the marl and phosphate deposits of North Carolina and tables of analyses of many hundred samples compiled from the station records, with a description of the geological features of the formations, and notes on distribution, varieties, and uses, including a chapter on the manufacture of superphosphates.

"Of North Carolina's mineral resources there is none which is of so much interest to the agricultural community as her beds of marls and phosphates. These deposits are distributed throughout the eastern portion of the State, and belong to one of the largest formations of the kind in the world. The portions of the Cenozoic and Mesozoic eras, which include these deposits, may broadly be said to extend along the coast of the Atlantic Ocean and the Gulf of Mexico from New Jersey to Texas. While the marls are not as rich in some fertilizing ingredients as the famous green sand marls of New Jersey, and the deposits of phosphates thus far discovered are less valuable than those of South Carolina, the supply is very extensive, and if properly utilized will prove of material value to the farming community, especially in the eastern portion of the State. These deposits of phosphates and marls are in many cases so closely connected that there is seen a great variety of material, ranging from a nearly pure carbonate of lime containing a trace of phosphate to that of a high-grade phosphate with only a small content of carbonate of lime. In addition to phospate of lime and carbonate of lime, the green sand varieties contain an appreciable percentage of potash. The value of all the different deposits is largely affected by the varying percentages of sand or other worthless material which they may contain. . . .

"Coprolites have been known for many years to occur in the marl deposits of the East and in the Triassic regions in Rockingham, Stokes, Chatham, and Moore counties, but it was not known that phosphates existed in sufficient quantities to be of agricultural value until the deposits at Castle Hayne were discovered in 1883 through the means of this station. . . . Since that year the station has assisted landowners who were interested in the development of these natural resources upon their property. . . .

"The most important phosphate deposits in North Carolina thus far investigated lie in a belt 15 to 20 miles wide, extending from the South Carolina line northeastward with a trend of the coast to the Neuse River. It runs through the counties of Columbus, Bladen, Sampson, Duplin, and includes a small part of Pender, Lenoir, Jones, and Onslow. A conglomerate of phosphatic nodules and marl, less rich in phosphate than the preceding, lies just below this and extends southward through Pender and New Hanover counties nearly to the coast.

"For home consumption the North Carolina phosphates are beginning to be considerably used and might be more extensively utilized, especially in the vicinity of the deposits...

"For convenience the products of these deposits can be divided into two classes, those which contain sufficient phosphoric acid for the profitable manufacture of acid phosphate for commercial use, and the lower grades, which can only be profitably used in the vicinity of the production. The manufacture of North Carolina acid phosphate is now being carried on to a considerable extent compared with former years. It has been found that an article containing from 10 to 13 per cent available phosphoric acid can be made at comparatively small cost. While the rock is not quite as high grade as that from South Carolina, it grinds readily and takes about one-third less acid, thus reducing the cost of manufacture, at the same time retaining a good percentage of phosphoric acid. . . .

...

"The lower grades of rock and the marls containing phosphoric acid, while they can not be profitably used in the manufacture of acid phosphate, will prove valuable for home use. The small cost at which they can be procured will doubtless make it profitable to ship them a considerable distance."

The action of lime and magnesia on the soluble phosphoric acid of the soil, C. SCHREIBER (Rev. Agron. Louvain, 4 (1895), No. 1, pp. 66-69).—Two complete fertilizers, one containing dicalcium phosphate mixed with sulphate of lime and carbonate of magnesia, and the other phosphate of soda with carbonates of lime and magnesia, were compared in experiments with oats and turnips on sandy, humus, and loam soils. The fertilizers were applied to the oats, which were followed by the turnips without further addition of fertilizers.

In every case the yield was much lower with the second fertilizer, the difference being particularly marked in case of turnips. This result was apparently due to the action of the carbonates of lime and magnesia in rendering the phosphoric acid of the phosphate of soda insoluble. The differences were more marked in case of the turnips because the retrograde action had become more complete.

The results of experiments on the humus soil confirmed the conclusions drawn by the author from previous experiments' that the phosphoric acid combined with the humus of moor soils which is readily soluble in alkaline ammonium citrate is almost useless for vegetation. Under certain circumstances, therefore, humus exerts on assimilable phosphoric acid an influence analogous to carbonate of lime.

The assimilation of the plant food of soils by plants, J. KÖNIG and E. HASELHOFF (Landw. Jahrb., 23 (1894), No. 6, pp. 1009-1030, pls. 3).—After a brief review of the work of other investigators in this line the authors report experiments made by them with barley and horse beans on 2 artificial soils. These soil mixtures had the following composition:

Artificial soil mixtures.

The absorptive power of these mixtures was tested by 2 methods with solutions of chlorid and nitrate of calcium, sulphate of potash, sulphate of magnesia, chlorid of ammonia, nitrate of soda, and superphosphate, each in 2 different degrees of concentration. In general from one-seventh to one-fourth of the lime, zero to one-third of the

Monographie agricole des terrains des Linbourg, 1893, part 1.

2 A notable omission in this review is the work of Dyer on Rothamsted soils (E. S. R., 5, p. 1013).

magnesia, one-fifth to one-half of the potash, and only traces of soda and sulphuric acid were absorbed, while phosphoric acid was completely retained. The addition of zeolite increased the amounts, especially of lime, magnesia, and potash absorbed, practically the same amounts being absorbed from the two solutions.

For the experiments with barley, glazed earthernware pots holding about 6 kg. were filled to a height of 8 cm. with sand (about 2 kg.) then to a height of 21.5 cm. with the soil mixtures (4 kg.). Six series of pots with each mixture were prepared, 1 series in each case receiving no fertilizer, while 5 were fertilized as shown in the following table:

Fertilizers used in pot experiments with barley.

The moisture was kept at 60 per cent of that required for complete saturation in pots filled with mixture 1, and 75 per cent in those filled with mixture 2.

The growth of barley was very poor on the check pots receiving no fertilizer, showing that the soil mixture contained little food assimilable by this plant. It was slightly better, however, on mixture 1 than on mixture 2, due probably to the fact that the former had been mixed about 6 months before the beginning of the experiment and had weathered to some extent, while the latter was mixed just prior to use in the experiments.

Although the results in the different series were somewhat irregular on account of the unfavorable physical properties of the soil they agree in general in showing that the yields increased with the increase of soluble fertilizing constituents present.

From analyses of the crop the following table is calculated, showing the extent to which the leading fertilizing constituents in the soluble and insoluble forms were assimilated:

Amounts of soluble and insoluble fertilizing constituents absorbed by barley.