IpM U^ Issued January 17, 1917. AWAII AGRICULTURAL EXPERIMENT STATION, J. M. WESTGATE, Agronomist in Charge. Bulletin No. 42 COMPOSITION OF HAWAIIAN SOIL PARTICLES. jm ofT~~p — BY WM. T. McGEORGE, Former Chemist, Hawaii Agricultural Experiment Station. UNDER THE SUPERVISION OP STATES RELATIONS SERVICE, Office of Experiment Stations, U. S. DEPARTMENT OF AGRICULTURE. WASHINGTON: GOVERNMENT PRINTING OFFICE. Issued January 17, 1917. HAWAII AGRICULTURAL EXPERIMENT STATION, J. M. WESTGATE, Agronomist in Charge. Bulletin No. 42. COMPOSITION OF HAWAIIAN SOIL PARTICLES. BY WM. T. McGEORGE, Former Chemist, Hawaii Agricultural Experiment Station. UNDER THE SUPERVISION OF STATES RELATIONS SERVICE, Office of Experiment Stations, U. S. DEPARTMENT OF AGRICULTURE. WASHINGTON: GOVERNMENT PRINTING OFFICE. 1917 HAWAII AGRICULTURAL EXPERIMENT STATION, HONOLULU. [Under the supervision of A. C. True, Director of the States Relations Service, United States Department of Agriculture.] E. W. Allen, Chief of Office of Experiment Stations. Waltee H. Evans, Chief of Division of Insular Stations, Office of Experiment Stations. STATION STAFF. J. M. Westgate, Agronomist in Charge. J. Edgar Higgins, Horticulturist. M. O. Johnson, 1 Chemist. F. G. Kratjss, Superintendent of Extension Work. J. B. Thompson, Assistant Agronomist, in Charge of Glenwood Substation. Alice R. Thompson, Assistant Chemist. V. S. Holt, Assistant Horticulturist. C. A. Sahr, Assistant Agronomist. A. T. Longley, In Charge of Cooperative Marketing Investigations. LETTER OF TRANSMITTAL Hawaii Agricultural Experiment Station. Honolulu, Hawaii, December 14, 1915. Sir : I have the honor to submit herewith, and recommend for publication as Bulletin No. 42 of the Hawaii Agricultural Experiment Station, a manuscript entitled "The Composition of Hawaiian Soil Particles," by Wm. T. McGeorge, formerly chemist of this station. The variations in Hawaiian soils as compared with the soils of the mainland of the United States are so great and unusual as to make it of economic importance to determine as many as possible of the fundamental causes of the variations. As pointed out in the accompanying manuscript, the size of the particles of different Hawaiian soils bears a distinct relation to their composition. Respectfully, J. M. Westgate, Agronomist in Charge. Dr. A. C. True, Director States Relations Service, U. S. Department of Agriculture, Washington, D. C. Publication recommended. A. C. True, Director. Publication authorized. D. F. Houston, Secretary of Agriculture. 1 Appointed July 25, 1915, to succeed Wm. T. McGeorge, transferred to U. S. Depart- ment of Agriculture, Bureau of Chemistry. (2) COMPOSITION OF HAWAIIAN SOIL PARTICLES. CONTENTS. Page. Introduction 1 Origin of Hawaiian soils 1 Changes during disintegration 5 Selection of soil types 6 Page. Composition of the soil particles 8 Properties of the soil particles 10 Conclusions 12 INTRODUCTION. One of the primary characteristics of Hawaiian soils is the wide diversity of types which makes difficult their classification according to the usual methods employed in soil surveys. A wide variation in chemical composition, as well as in physical properties, is found within very short distances. During a recent investigation in this laboratory upon the determination of humus, the character of the clay in Hawaiian soils, as regards certain of its properties, was found to be radically different from that in mainland soils. Chief among these abnormal properties is the incomplete coagulation when coag- ulants are added. This is especially true in case of addition of ammonium carbonate, which has been successfully used on mainland soils for the coagulation of clay in humus extracts. This peculiarity of the clay has led to a study of the composition of the coagulable and noncoagulable grains and a further investiga- tion upon the composition of the clay, fine silt, silt, fine sand, and coarse sand separates in the important Hawaiian types of soil differ- ing in color, chemical composition, and physical properties. ORIGIN OF HAWAIIAN SOILS. In order to understand clearly the composition of the soil separates, it is necessary to know something of the origin of Hawaiian soils, at least the three possible sources from which they may be derived, namely, volcanic lava, volcanic ash, and coral sand. As, with the exception of small areas near the sea. coral sand need not be con- sidered a- a factor in soil format ion in the islands, and as there is -16 (3) little material difference in the composition of the lava and ash, the source of Hawaiian soils narrows down to volcanic basalts of a more or less uniform composition. Analyses of lava, volcanic ash, and coral sand are given in the following table : Analyses of lava, volcanic ash, and coral sand. Constituents. Lava. From Oahu. Sample B. Sample E. Sample F. From Hawaii. Sample No. 501. Sample No. 502. Sample No. 503. Silica (Si0 2 ) Alumina (AI2O3) Ferric oxid (Fe 2 3 ) Ferrous oxid (FeO) Manganese oxid (M^O^ Lime(CaO) Magnesia (MgO) Potash(K 2 0) Soda(Na 2 0) Sulphur trioxid (S0 3 ) Phosphorus pentoxid (P2O5) Titanic oxid (Ti 2 ) Moisture Per cent. 52.45 11.49 3.66 6.90 .36 10.32 5.81 .89 2.44 .20 .38 4.07 1.02 Per cent. 52.15 12.57 3.36 7.07 .50 8.54 6.51 .84 2.64 .61 .28 4.07 .94 Per cent. 51. 98 15.85 2.90 6.84 .92 9.57 5.61 .97 2.70 .51 .22 1.50 1.04 Per cent. 52.24 16.00 3.73 5.89 .68 9.54 5.90 .86 2.65 .53 .11 1.50 .54 Per cent. 48.88 12.84 .30 8.52 .31 9.55 10.29 .75 1.44 .33 .21 2.54 4.45 Per cent. 48.55 14.83 2.44 6.07 .66 8.56 14.22 .72 1.56 .19 .22 2.15 .09 Per cent. 52.07 14.12 2.64 -7.01 .72 10.71 7.51 .74 1.93 .35 .24 2.42 Constituents. Lava. From II awaii. Sample Sample No. 504. No. 505. Per cent. Per cent. 51.25 49.94 14.36 14.42 3.30 1.04 6.43 8.01 .44 .20 10.65 11.59 9.12 9.08 .64 .80 1.96 1.79 .33 .33 .17 .26 2.35 2.86 Sample No. 519. Volcanic ash. From Maui. Sample No. 506. Sample No. 507. From Oahu. Sample No. 132. Coral sand. From Oahu. Sample No. 227. Silica (Si0 2 ) Alumina (A1 2 3 ) Ferric oxid (Fe 2 3 ) Ferrous oxid (FeO) Manganese oxid (Mn 2 04) — Lime(CaO) Magnesia (MgO) Potash(K 2 0) , Soda (Na 2 0; Sulphur trioxid (S0 3 ) Phosphorus pentoxid (P 2 5 ) Titanic oxid (Ti0 2 ) Moisture Per cent. 50.69 15.62 .49 4.65 .28 11.14 6.55 .90 2.56 .78 .34 5.53 .10 Per cent. 45.54 17.42 8.60 Per cent. 46.98 16.62 7.08 1.17 8.90 6.14 1.82 2.92 .36 .63 6.00 .74 .18 7.16 5.58 1.32 2.62 .46 .59 6.60 1.55 Per cent. 36.82 18.08 10.40 4.32 .46 9.52 .54 5.62 10.20 .18 .70 5.50 .09 Per cent. 2.60 .21 92.40 2.90 .31 .46 .55 .21 j0 Samples A, B, E, and F are from unaltered lava in the Wahiawa district of Oahu. Nos. 501 to 505, inclusive, are from the different flows of Mauna Loa on the Island of Hawaii. No. 501 was taken from the flow of 1823 and had undergone a slight decomposition; No. 502 was taken from the flow of 1868 and showed slight changes in appearance, due probably to hydration and leaching; No. 503 came from the flow of 1883; No. 504 from that of 1907; and No. 505 from the small overflow of 1910 at Kilauea. No. 519 is a sample of " Pele's Hair." a term that is used to describe the hair-like threads of lava formed at Kilauea by explosions in the molten lava. Nos. 506 and 507 are black ash from Haleakala Crater on Maui, while Xo. 132 is a sample of black ash from Oahu which had been sub- merged at one time by the sea. Xo. 227 is a sample of coral sand from the island of Oahu. There is a marked similarity in the composition of the lavas from both islands. xV slight variation in the content of soda and magnesia is the only perceptible difference. The same is also true of the volcanic ash from different sources, except that potash should be included as one of the variable constituents. The coral sand contains 92.4 per cent of carbonate of lime. The impor- tant silicates occurring in the lavas include the pyroxenes, amphi- boles, and soda-lime feldspars, while the ash contains more or less magnetic iron oxid. The primary agent of disintegration in Hawaii is weathering. However, the climatic factors influencing decomposition vary so widely even in adjacent districts that the soils formed are far from uniform in composition or properties. Eainfall varies from a frac- tion of an inch to over 200 inches per annum, hence there are humid, dry, and even arid districts. Temperature changes, while not rapid, vary from the tropical heat to temperate conditions, with snow at times in the higher mountains. Again there must be included as an agent of disintegration the trade winds which play no small part in the transportation of soil grains. The process of lava disintegra- tion is generally referred to as laterisation, but in certain of the districts submersion by the sea following their formation has ma- terially influenced the disintegration of the laterite and the com- position of the soil. Since practically all the known weathering agents are concerned in the formation of Hawaiian soils, acting either separately or in different combinations, it is not surprising that the types vary so greatly in closely situated districts. CHANGES DURING DISINTEGRATION. In a previous publication of this station 1 analyses are given show- ing the effects of disintegration on the composition of lava during the process of soil formation. These analyses are reproduced here in order to show more clearly the relation between the composition of the soil particles and the original lava. 1 Hawaii Sta. Bui. 2G (1912). Analyses of lava and adjacent lava disintegration products. Constituents. C. D. G. A. Disinte- B. Disinte- E. Disinte- F. Lava. gration products. Lava. gration products. Lava. gration products. Lava. Per cent. Per cent. Per cent. Per cent. Per cent. Per cent. Per cent. 52.45 20.29 52.15 24.01 51.98 26.82 52.24 11.49 37.97 12.57 36.27 15.85 30.13 16.00 3.66 15.01 3.36 14.29 2.90 16.86 3.73 6.90 3.22 7.07 3.31 6.84 3.03 5.89 .36 .19 .50 .43 .92 .06 .68 10.32 .33 8.54 .17 9.57 .22 9.54 '5.81 .20 6.51 .09 5.61 .11 5.90 .89 .25 .84 .24 .97 .46 .86 2.44 .27 2.64 .31 2.70 .57 2.65 .20 .78 .61 .49 .51 .74 .53 .38 .23 .28 .34 .22 .19 .11 4.07 4.69 4.07 4. 84 1.50 2.21 1.50 1.02 16.84 .94 15.61 1.04 18.34 .54 H. Disinte- gration products. Silica (Si0 2 ) Alumina (Al 2 3 ) Ferric oxid (Fe 2 03> Ferrousoxid (FeO) Manganese oxid (M113O4) — Lime(CaO) Magnesia (MgO) Potash (K 2 0) Soda(Na 2 0) Sulphur trioxid (S0 3 ) Phosphorus pentoxid (P2O5) Titanic oxid (Ti0 2 ) Combined water (H 2 0) Per cent. 32.00 35.28 11.80 1.53 .08 .22 .14 .30 .61 .70 .04 2.13 15.06 Samples A, B, E, and F are the unaltered lava, while C, D, G, and H are the adjacent weathered products or soil formed from the respective lava samples. These samples were taken by W. P. Kelley from gulches on Oahu, where large exposed lava bowlders have undergone weathering to such an extent that samples may be taken showing all stages of disintegration from the unaltered lava rock to the soil. The alkalis and silica are the most soluble constituents, and the former are almost entirely leached away in the process of disintegration. The iron is rapidly oxidized to the ferric condition, accompanied by a change to red, yellow, or brown soil, depending on the state of hydration. SELECTION OF SOIL TYPES. In selecting soils for this investigation, the policy of selecting all the more important soil types, adopted in previous soil studies in this laboratory, was pursued. The impossibility of drawing con- clusions from results obtained from one type of Hawaiian soil has been brought out in previous bulletins of this station. The mechan- ical and chemical composition of the soils used are given in the fol- lowing tables : Mechanical analyses of the soils. Soil particles. Soil No. 164. Soil No. 291. Soil No. 292. Soil No. 339. Soil No. 392. Soil No. 428. Soil No. 448. Soil No. 474. Soil No. 547. Clay Per cent. 21.10 51.70 19.50 3.79 } ■» Per cent. 59. 35 12.13 7.28 7.46 / .39 1 Per cent. 7.23 12.41 8.69 22.04 18.75 20.91 Per cent. 19.19 22.37 20.42 18.13 .22 .13 Per cent. 7.87 19.36 13.93 35. 71 10.22 Per cent. 0.69 1.76 5.38 15.83 32.82 13.81 Per cent. 6.85 20.00 13.45 16.31 8.60 1.94 Per cent. 5.24 24.20 18.00 30.70 } 3.43 Per cent. 9.33 Fine silt 35.00 Silt 30. 15 Fine sand 10.75 Coarse sand 1.57 Chemical composition of the soils. Constituents. Soil Soil Soil Soil Soil Soil Soil Soil No. 104. No. 291. No. 292. No. 339. No. 392. No. 428. No. 448. No. 474. Per ct. Pit ct. Per ct. Per ct. Per ct. Per ct. Per ct. Per ct. 1.22 9. 33 7.65 8.90 5. 51 14.94 L6.00 13.59 48.11 41.21 38.49 33.75 29. (14 34.99 15. 10 33.77 37.47 15.89 16.63 22. 69 15. 72 8.24 19.20 7.00 3.05 15.39 12. 85 11.60 24. 78 10.73 lti. 64 16. 79 1.72 1.25 2.00 2.66 1.80 3.20 4.20 1.80 .10 .18 .24 .07 2.26 .20 .0(1 .07 .12 .67 1.84 .39 .52 1.91 .50 3.80 1.22 1.41 8.47 .24 .50 2.24 1.80 .85 .48 .17 .39 .13 .40 .24 .15 .72 1.46 .40 1.36 .40 .21 1.40 .68 .10 .07 .20 .57 .26 .28 .22 .29 2.78 .44 .09 .08 .18 .31 .45 .53 . 45 3.56 12.77 8.42 19.15 19.00 22. 24 25.58 20.01 Soil No. 547. Moisture Insoluble matter Ferric oxid ( Fe2C>3) Alumina ( A1 2 3 ) Titanic oxid ( Ti0 2 ) Manganese oxid (M113O4) Lime(CaO) Magnesia (MgO) Potash(K 2 0) Soda(Na 2 0) Phosphorus pentoxid (P2O5) . Sulphur trioxid (S0 3 ) Volatile matter Per ct. 3.12 34. 54 30.84 10.68 6.20 .40 1.25 .19 .13 .43 .10 12.20 The above analyses were made by extraction with hydrochloric acid. On fusion with sodium carbonate the analysis of soil No. 164 gave 18.9 per cent titanic oxid. Soil No. 164 is a peculiar, fine-grained, gray, silty soil, evidently of residual formation. It has an unusually high specific gravity (2.8) and resembles more a mineral deposit than a soil. Soil No. 291 is very unlike the normal clay soils of the islands. It is brown in color and is very similar in physical properties to the adobe soils of the mainland. Drainage is very poor and plowing difficult, and when the soil dries it becomes almost as hard as cement. It is probably a transported soil, as it occurs in the valleys or gulches extending back into the mountains. No. 292 is a sandy soil formed from the disintegration and decom- position of volcanic ash. It is highly productive, owing to its excel- lent physical and chemical composition. No. 339, a silty soil from windward Oahu, is very productive and is devoted primarily to rice culture. No. 392 is representative of the types of red silty soils found in the islands. No. 428, a sandy soil from the Olaa district of Hawaii, has been formed from the disintegration of lava under very humid conditions, and hence is very high in organic matter. No. 448 represents a yellow clay silt found more or less widely dis- tributed throughout the islands. It contains a notably high content of combined moisture. Xo. 474 is a highly organic sandy silt from the Waimea district of Hawaii. It has an extremely loose structure, making it very dusty, but it is highly productive. No. 547 was chosen as representing the brown clay silts of the islands and as belonging to the class of clays in which the iron con- tent is greater than the alumina. There is another class in which the alumina predominates. 8 COMPOSITION OF THE SOIL PARTICLES. Analyses of the soil particles were made by fusion with sodium car- bonate. The results are given in the following table: Composition of the soil particles. SILICA CONTENT. Soil particles. Clay Fine silt — Silt Fine sand . . Coarse sand. Soil No. 164. Per cent. 32.70 30.10 1.72 2.33 Soil No. 291. Per cent. 47.75 42.80 35.50 32.50 29.90 Soil No. 292. Per cent, 44.25 44.75 38.00 43.95 33.25 Soil No. 339. Per cent. 38. 10 37.90 34.50 31.70 31.75 Soil No. 392. Per cent. 32.50 28.10 20.60 25.60 22.80 Soil No. 428. Per cent. 20.35 31.70 34.30 38.10 36.15 Soil No. 448. Per cent. 12.48 20.70 16.30 19.05 27.28 Soil No. 474. Per cent, 34.30 42. 40 36.50 39.40 33.45 Soil No. 547. Per cent. 32.10 24.80 6.37 7.36 10.92 IRON CONTENT. Clay 19.21 15.30 45.80 39.25 15.30 18.98 26.60 32.15 23.92 11.53 13.36 18.28 29.05 17.10 15.85 15. 81 20.90 30.60 20.95 16.80 16.42 18.90 18.92 18.05 12.86 18.05 16.70 17.98 16.60 25.16 30.50 31.60 24.95 22.70 10.01 9.61 10.56 15. 96 14.96 22 35 Fine silt Silt 23.70 43.90 Fine sand 41.70 39 10 ALUMINA CONTENT. Clay.. Fine silt Silt Fine sand . . Coarse sand. 32.29 28.95 13.72 30.82 27.53 26.52 23.93 22.48 33.37 30.86 29.51 26.64 10.94 13.60 40.39 37.95 34. 24 26.05 34.75 42.92 39.05 40.91 38.93 49.13 47.95 26.68 24.16 20.72 23.87 48.42 36.44 34.71 41.14 20.42 30.15 29.60 32.50 30.02 27.26 32.40 35.22 17.19 30.50 36.41 TITANIUM CONTENT. Clay 8.91 15.29 26.50 21.45 3.45 4.72 6.40 4.38 2.99 3.16 3.31 5.47 5.68 1.79 2.92 4.52 7.22 8.37 2.94 2.77 3.70 5.79 5.4£ 3.34 3.62 3.89 5.87 4.36 3.35 4.52 5.92 7.48 7.68 3.54 2.19 2.59 7.41 2.21 3.39 6.31 Fine silt 10.19 Silt 17.23 Fine sand 14.32 12.01 PHOSPHORIC ACID CONTENT. Clay 0.39 1.76 .25 .68 0.47 1.53 .57 .66 .95 1.70 2.22 .81 .53 .61 0.84 1.02 .54 .54 .61 0.91 2.08 .15 .41 .38 1.32 1.58 .67 .63 .38 1.65 1.74 .81 .65 .56 4.47 4.45 1.83 1.51 1.19 1.24 Fine silt 1.64 Silt .58 .38 .88 MANGANESE CONTENT. Clay 0.20 .29 .60 .40 0.54 .55 1.30 .68 2.60 0.11 .39 .97 .61 1.24 0.04 .45 .54 .41 1.88 0.34 2.43 3.18 5.12 8.75 0.11 1.08 1.41 .49 1.17 0.18 .31 .57 .42 .68 0.46 .53 .66 .67 .95 0.15 Fine silt .33 Silt .46 Fine sand .60 Coarse sand 4.35 LIME CONTENT. Clav 0.72 .96 .30 1.04 1.09 1.73 1.47 3.50 1.33 1.56 3.29 .83 1.10 4.37 1.11 .97 .92 .98 1.79 1.25 1.63 1.66 .90 1.24 2.46 6.43 5.90 8.28 7.63 1.32 1.29 1.13 2.08 3.05 3.04 6.50 6.46 6.77 6.92 1.16 Fine silt .87 Silt .69 Fine sand 1.02 Coarse sand 2.23 Composition of the soil particles — Continued. MAGNESIA CONTENT. Soil particles. Clay Fine silt — Silt Fine sand. . Coarse sand. Soil No. 164. Per cent. 0.76 2.74 2.05 2.65 Soil No. 291 Per cent. 0.99 2.14 1.59 2.27 2.35 Soil No. 292. Per cent 1.18 2.73 3.27 2.27 23.49 Soil No. 339. Per cent. 1.27 .96 1.04 1.26 3.22 Soil No. 392. Per cent. Per cent Soil No. 428. 0.85 1.22 .95 1.59 1.57 1.67 5.98 4.95 9.18 10.38 Soil No. 448. Soil Soil No. 471. No. 547. Per cent. P