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Home , Caroline Islands, Koror, Palau

Soils and of the '

A.J. VESSEL and Roy W. SIMONSON2

SOILS OF THE PALAU ISLANDS range from shown in Figure 1. Lying 7° north of the deeply weathered Latosols- to shallow, rocky equator, the are in the same latitude as Lithosols, and include Regosols, Alluvial Colombia and Venezuela. Soils, and Organic Soils. Most extensive in The Palau chain stretches appro ximately 50 the islands are the Larosols, ofgeneral interest miles, from at the north to because of their wide distribution in the at the south. From east to west, the dimen ­ humid tropics . Associated soils are much less sions of the chain range from 3 to 25 miles, extensive but are more impo rtant to local as measured to the outer barrier reefs. food production . The latter also illustrate The total land of the group, which effects of local factors in soil formation . Data consists of some 350 closely spaced islands on characteristics, distribution, and utilization and islets, is 175 square miles. Babelthuap, of the soils and a preliminary evaluation of largest in the group, has an area of al­ their agricultural potentialities are given in most 140 square miles. The bulk of the re­ this paper. More complete descriptions of the maining land area is distributed among eight soils are part of a comprehensive report on additional islands. Most of the 350 islands the geology and soils ofthe islands now being and islets of the chain are tiny reefs or bars, prepared for publication as a professional barely above sea level. paper of the U. S. Geological Survey. Physiography and Topography GEOGRAPHIC SETTING The four types ofislands in the Palau group Locationand Extent are reef and islands, platform islands, high limestone islands, and volcanic islands Most western group ofthe , (Tayama, 1953). The reef and atoll islands, the Palau chain is almost directly south of by far the most numerous, are Rat land sur­ Tokyo and due east of .Location faces only a few feet above sea level. Ex­ of the group in the western Pacific is amples of this type are Kayangel atoll at the north end of the chain and the many small 1 A reconnaissance soil survey of the islands was unnamed reefs and north of . made in 1948 as a parr of a cooperative program of soil and geo logi cal mapping of islands in the western The platform islands, also mainly Rat, are a carried ou r cooperarively by rhe Corps of little higher than the reefs and atolls. Angaur Eng ineers, U.S. Army, and U. S. Geological Survey, and Peleliu are chiefly of this type, though Deparrment of the Intetior. M anuscripr received June 12, 1957. part of each consists of limestone ridges. The 2 Soil Scientisrs, Soil Survey, Soil Cons ervarion high limeston e islands rise steeply out of the Service, U. S. D epartment of Agriculture. Th e aurhors sea and are mostly narrow and elongated in were on assignment to rhe U. S. Geological Survey and rhe Corps of Engin eers for rhe mapping of rhe Palau shape . A few have the form of mushrooms. Islands. The principal high limestone islands are 3 Larosol is a term proposed within the past few Urukth apel and Eil Malk; these and the nu­ to include zonal soils formerly called Laterites, Reddis h-Brown Lateritic soils, and Yellowish-Brown merous small ones all lie between Ko ror and Lateriti c soils (K ellogg, 1949). Peleliu, approximately 25 miles apart. Parts of

281 282 PACIFIC SCIENCE, Vol. XII, October, 1958

l OS' 150 0 165 0 YOKO HAMA

30·

.Bonin Is

10 " r- Marianas

~ G : : m 15 0 MAOILn;~.. e . 010/ Jj: ~~~ 0 /0 1. 1''/ .P.?j ~.. <; /YoPC . .r- J. ~· ~'/.H n d a n a o ~,/ " a ..r. 9 J i, n ,~ ~ ~1J" 525 PA LAU IS. e d " I s,

0'

Di stances in nautical miles

10 50 120 0 150'

FIG. 1. Map showing the location of the Palau Island s in the western Pacific Ocean.

Peleliu, Angaur, and and mu ch of one ofthe ridges in northwestern Babelthuap. Auluptagel are also high limestone ridges. The volcanic islands (Babelthuap, Arakabe­ The maximum elevation of the high limestone san, M alakal, Auluptagel , and K oror) are all islands is 686 feet above sea level on Uruk­ closely grouped in the northern part of the thapel, Slopes of these islands are generally chain. As mentioned earlier, Auluptagel and steep or very steep though a few have small K oror are partly volcanic rock and partly central depressions with mild relief. limestone. The volcanic islands, so named because of Soil Parent M aterials the un derlying basement rock, are generally hilly to rolling with local relief commonly The variety of rocks from which soils have measurable in tens of feet .Slopes and ridge been derived is relatively small in the Palaus . crests are rounded and sub dued. Babelthuap The platform and high limestone islands con­ has three prominent ridges running roughly sist of former reefs. The present surface parallel to the long north-south axis of the of the high limestone islands is largely a mass island . Th e highest elevation in the Palau of rubble of assorted sizes. Much of the land Islands is that of 794 feet above sea level on surface of the platform islands also consists So ils of P alau - VESSEL AND SIMONSON 283

of rubble, commonly small in size. The princi­ vananon is about ten degrees. Prevailing pal volcanic rocks range from olivine-augite winds are from the northeast and east from basalts to silicic hornblende dacites (Corwin, November to June and from the south and 1951) identified as andesitic agglomerates by southwest for the remainder of the . J apanese geologists (Tayama, 1953) and also known as basaltic and andesitic volcanic brec­ cias. Associated with the flow rocks and ag­ The native vegetation (Fosberg, 1946) in glomerates on Babelth uap are some basic vol­ the Palau Islands was , which re­ canic tuffs. Interbedded sedimentary clays mains in only a few places on Babelthuap. and lignite comprise the surface formations in The rain forest consists of large trees, includ­ a few places in western and southeastern ing Parinarium, Campnosperma, Couthovia, Babelthuap. Cynometra, , Ficus, Semecurpus, Ran­ The distribution of rocks on the Palau dia, Fagraea, Pittosporum, Schelftera, Horsfieldia, Islands is strongly reflected in the distribution and many others. Growing also in the rain of soils (Fig. 2). Rocks of volcanic origin are forest are such palms as Pseudopinanga and parent materials for most of the Latosols. Exorrhiza; an occasional slender ; Some latosolic soils have also been formed such climbers as Preycinetia, Canavalia, Piper, from interbedded sedimentary clays. Deep aroids, and Ipomoea; also ferns, orchids, and soils with distinct horizons have' not been other epiph ytes. On both the low and high formed from limestones, most of which have limestone islands, vegetative cover consists rubble surfaces. Where the volcanic rocks are mainly of small to medium-sized trees and exposed on steep or moderately steep slopes, shrubs because moisture condition s are un­ shallow rocky Lithosols have been formed. favorable for plant growth. Deep unconsolidated materials of recent ori­ The most extensive vegetative type today gin have given rise to Regosols, Alluvial Soils, is anth ropic savanna consisting of coarse and Organic Soils. grasses, weeds, and occasional shrubs. Com­ mon genera in the savanna are Ischaemum, Climate Paspalum, Digitaria, Miscanthus, Lycopodium, Nepenthes, and Pandanus (Fosberg, 1946). Typical of the hum id tropics, the islands Soils of extremely low fertility support almost have heavy annual rainfall and high mean pure stands of a fern, Gleichenia linearis. with small seasonal differences (U. S. Dept. ofCommerce, 1953). The islands SOILS also have rather steady winds, lying as they do in the trade-wind belt. The mean annual The general character and distribution of is 148 inches, with a maximum soils were determined through a reconnais­ of about 19 inches in July and a minimum of sance survey, according to procedures already nearly 8 inches in March. On the average, at described (Simonson, 1953; Soil Survey Staff, least 15 days of each month have 0.04 inch 1951). This reconnaissance survey was part or more of rain, whereas 7 days in July have 1 of a program of soil and geologic investiga­ inch or more. The average relative hum idity tions in the western Pacific Ocean (Simonson, is 82 per cent, with a low of 79 per cent in 1953). How the soils were being used was March and a high of 83 per cent in July, No ­ observed during the field mapping from vember, and December. The mean annual March through August, 1948. temp erature is 810 F. The maximum and mini­ Distribution of the soils and land types of mum mean monthly temperatures are but one the islands is shown in Figure 2. The map degree higher and lower, whereas the diurnal units are either soil associations or miscel- 284 PACIFIC SCIENCE, Vol. XII, October, 1958

BAB£LTHUAP

t 'i' ANGAVR

Legend

Soils and Land Types of Palau Islands

Latasols and Latosolic Soils E3 Latosols from Brecc ias ITIIIIID Bauxitic Latosols f rom Breccias ~ Lalos ols from Tuffs f2222:l Lctosolic Soils from Cloys

Regosols, A'lIuvial Salls , and Organic Soils

l2!JQ0J Shioya (:=::J All uvial soils

~ Muck and Peat

Llthosols, Stony L and, Roc k Land,and Swamp . [=::::J Lithosols f rom Volcanic Rocks ! ARAKABESAN _ 1:'''':'';:''·.1 Smoot h St ony Land IIllllIIIIIIIJI limestone Outcrop -~~~~~:~~;g. - -~-- ~, f""""""l Mangrove swamp

5Ml LES '---'---'-----'--'----', o ~VL Vp rAGEL

FIG. 2. Map showing the distributio n of major soil associa tions and miscellaneous lan d types of the Palau Islands. High limestone islands and others that are not inh abited and consist of a sing le miscellaneous land type are not shown. Anga ur and Peleliu, which ate at the south end of the chain, are shown by inset maps .

laneous land types, with one exception ­ into great soil groups or sub orders.' Each Shioya sand, a soil type. associatio n is then named for the dominant Each soil association consists of one or great soil group or suborder. Th e associations more geographic areas with a restricted com­ are described by' listing the component soils bination of soil types occurring together in a 4 The classification system followed in th is paper is characteristic and repeating pattern. The in­ the one outlined by Baldw in, Kellogg, and Th orp dividual soil types in each association have (1938) as modified in a group of papers in Soil Science, not been described and identified, however, as Vol. 67, N o.2, Febru ary 1949, with two excepti on s. The term and co ncept of "Larosol" as pro posed by they would be in detailed surveys. The com­ Kell og g (1949) are used . The term " Organic Soils " is ponent soils in each association are classified used as a substitute for "Bog Soils." Soils of Palau- VESSEL AND SIMONSON 285 and their approximate proportions. Patterns The Latosols ofthe Palaus are well drained, of occurrence of component soils also may red to yellowish, friable, strongly acid, deep. be indicated. The component soils are de­ and ferruginous or bauxitic soils derived scribed either by giving full morphological mainly from volcanic rocks. The regoliths details for representative profiles together from volcanic rocks are weathered to great with data on topography and other features depths, but the soils do not seem to have or by comparisons with soils that have been correspondingly deep solums . The few lato­ fully described. solic soils formed from sedimentary clays are Miscellaneous land types are geographic less deeply weathered and have shallower units without classifiable soils or with low solums than do those derived from volcanic proportions of such soils. Examples in the rocks . Palau Islands are smooth stony land and These soils occur in moderately dissected limestone outcrop. Stray patches of classifia­ uplands with a dendritic pattern of drainage­ ble soils occur in each of these units but ways. Ridge crests are generally narrow, as are comprise a negligible portion of the total area. the valleys, and the intervening rounded The profile descriptions use horizon con­ slopes are relatively long. Local relief, i.e., cepts and terminology as given in the Soil differences in elevation within a unit area of Survey Manual (Soil Survey Staff, 1951), un­ approximately 160 acres (one-fourth square less otherwise stated. The identification of mile), are measurable in tens of feet, for the field textures, i.e., apparent texture as de­ most part. In a few places local relief is meas­ termined by the fingers when the profile was urable in one or two hundreds of feet, whereas being described, is given for individual hori­ in others it may be in feet. zons. Pinholes refer to pores that are 1 mm . Three associations are dominated bv Lato­ or less in diameter, whereas wormholes are sols formed from volcanic rocks, wh'ereas a tubular channels about 3 mm. in diameter. fourth consists of latosolic soils derived from Numbers ofpinholes , wormholes, roots , stone .clays. Brief descriptive names are used to fragments, and concretions are indicated by identify the major group in each association. three relative classes, viz., few, common, and Such names are not being suggested as proper many. Concretions are roughly spherical, un­ names for great soil groups but are intended less otherwise noted, and their sizes are re­ for local identification of the soils. When the ferred to the same limits as granular structure name of an association is used as a subsection a~other (see Soil Survey Manual for these size limits). heading, it is followed by name or Each profile description is preceded by a names in parentheses . These names in paren­ brief statement on the geographic setting, theses identify the associations on the map of and some are followed by comments not larger scale in the report on military geology readily included in the description itself. ofthe islands (U. S. Department of the Army, 1956). The information on the larger map has Latosols and Latosolic Soils been generalized in preparing the map in Figure 2. TheLarosols are by far the most extensive 1.Latosols from Breccias(PalauAssociation) soils in the Palau Islands , comprising some This association is dominated by Larosols 60 per cent of the total land area. As shown that are red or reddish brown in the deeper by the map in Figure 2, they are dominant on profile. Colors are mainly of 2.5YR and 5YR Babelthuap, Koror, Arakabesan, and Malakal , hues 5 though a few soils are strong brown and form the north tip ofAuluptagel. Despite their large acreage, however, they have lim­ 5 Munsell color notations. The application of this system of color notations to soils is discussed in the ited importance to local food production. Soil Survey M anual (Soil Survey Staff. 1951). 286 PACIFIC SCIENCE, Vol. XII, October, 1958

(7.5YR hue) and a very few yellowish brown granules; slightly hard, fri­ (lOYR hue) below the A horizon. Bauxitic able, slightly plastic; roots Latosols, Alluvial Soils, and Lithosols or common; few pinholes, lithosolic soils are minor components of the wormholes, and stone frag­ association. With a total area of 78 square ments; strongly acid. miles, this association is much the largest in B22 26-33" Yellowish-red (5YR 4/6) the Palau Islands. It extends from one end of silty clay, yellowish red Babelthuap to the other, covers all of Araka­ (5YR 5/6) when dry; com­ besan and Malakal , and occupies those parts pound structure of mod­ of Koror and Auluptagel underlain by vol­ erate fine and medium canic rocks. angular blocks breaking Topography is largely hilly; dominant readily to moderate medi­ slope gradients fall between 15 and 45 per um and fine granules; cent. Departures from the dominant topog­ slightly hard; friable, raphy occur on major divides, where the up­ slightly plastic; few roots; lands are undulating or gently rolling , and pinholes and wormholes immediately adjacent to the valleys of large common; strongly acid. streams, where slopes are commonly steep. B n 33-39" Comparable to B n in tex­ Hilly topography, however, dominates the ture, structure, and con­ association. sistence but dark red A profile description to illustrate the major (2.5YR 3/8) in color; few reddish Latosols of the association follows. roots; pinholes and worm­ (a) Setting. This profile was described and holes common; strongly sampled on the island of Arakabesan about acid.

1,000 yards west of the causeway leading to CI 39-60" Brindled and finely varie­ Koror. The site is about 100 feet above sea gated red, yellowish-red, level in well-dissected uplands and has a slope pale-yellow, and light-gray of 15 per cent to the east. Vegetation in the (intermediate colors also vicinity has been disturbed by fire and by present) silty clay loam; cutting, though there was little cultivation massive; soft, very friable; in evidence. strongly acid.

(b) Profile Description. C2 60-102" Similar to C horizon but Al 0-12" Dark reddish-brown (5YR with lower proportions of 3/4) silty clay loam, dark grays in the color pattern.

brown (7.5YR 3/4) when C3 102-120" Finely variegated reddish­ dry; weak, fine and very yellow and light-gray silty fine granular structure; . clay loam with few medi­ soft, very friable; many um distinct mottles of roots ; fewstone fragments; weak red; massive in place strongly acid. but breaks out in' weak

B2 I 12-26" Dark red (2.5YR 3/6) silty coarse plates with black clay, yellowish red (5YR coatin gs on many faces; 4/6) when dry; compound slightly hard, firm; strong­ structure of moderate fine ly acid. and medium subangular (c) Additional Notes. The identification of

blocks breaking readily to the B2 2 and Bn horizons is open to question. moderate fine and medium The B2 2 is like the adjacent ones in texture, Soi ls of Palau - VESSEL AND SIMONSON 287

structure, and consistence but not in color. islands. Striking features of these soils are the The differences may reflect marked banding in large numbers of concretions on the surface the original parent materials or disturbance of .and in the profile. Approximately half of the some kind , possibly by man . Disturbance total area of this association consists of red­ seems probable in view of widespread occur­ dish, bauxitic Latosols. Most ofthe remainder rence ofpottery fragments at some depth in consists of Latoso ls that are low or lacking in Latosol profiles in the Palau Islands. Labora­ concretions, but there are also minor propor­ tory data also suggest the possibility that the tions of Lithosols or lithosolic soils and of

present B 23 horizon may at one time have Alluvial Soils. Much less extensive than been an A horizo n, later covered by soil ma­ Latosols from Breccias, this association has a terial of similar composition moved down ­ total of 19 square miles, all on Babelthuap. slope from higher uplands . Major areas arein the west central part of the The slope 'gradient at the profile site on island, though two small ones are near the Arakabesan falls near the lower end of the south . dominant range for the association as a whole . Topography is dominantly hilly. Slopes Consequently, the solum is thicker than aver­ may be slightly steeper, on the average, than age. It is estimated that 10 per cent of the they are in the association of Latosols from Latosols in this association have deeper solums Breccias. Local relief is commonly measurable and that 60 per cent have slightly shallower in many tens of feet. solums, i.e., between 2' and 3 feet. The re­ A profile description representative of the maining 30 per cent have solum thicknesses domi nant bauxitic Latosol of the association falling between 1 and 2 feet. Regardless of is as follows : variations in solum thickness the regolith is (a) Setting. The profile was described and deep for all Larosols in this association, com­ sampled in a former strip mine used for the monly ranging from 10 to 60 feet. Occasion­ extraction of bauxitic ore, approximately ally, thickness of the regolith may exceed 60 1,600 yards south of on Babel­ feet to the underl ying basaltic or andesitic thuap. The site has a slope of abou t 15 per " volcanic Breccias. cent to the east. Vegetation near the strip Concretionary or bauxitic Latosols, Litho­ mine consists of coarse grasses and brush sols and lithosolic soils, and Alluvial Soils interspersed with almost pure stands of ferns comprise from 10 to 15 per cent of the associ­ (Gleichenia linearis). ation. Proportions of these three minor (b) Profile Description. groups are appro ximately equal. The concre­ A l 0-6" Brown (7.5YR4/4) gravel­ tionary Latosols are similar to the dominant ly loam ; moderate fine soils in the association of bauxitic Latosols granular structure; soft, fri­ from Breccias. In contras t to the Latosols, able; brownish coarse and the Lithosols and lithosolic soils are formed very coarse vesicular platy in shallow regoliths, usually marked by rock concretions common, few outcrops. The Alluvial Soils occupy toe slopes brown fine concretions; and narrow valleys and are similar to those many very fine, fine, and described in the subsection on Regosols, medium roots; few small Alluvial Soils, and Organic Soils. worm casts; very strongly acid.

2. Bauxitic Latosols from Breccias (Babel­ B 2 6-18" Red (2.5YR 4/8) silty thuap Association) clay; compound structure The dominant soils of this association are of moderate coarse sub­ the most strongly weathered Latosols of the angular blocks breakin g 288 PACIFIC SCIENCE, Vol. XII, October, 1958

under pressure into moder­ The nature and distribution of concretions ate fine and medium sub ­ in the profiles of dom inant Latosols in this angular blocks; slightly association tend to follow certain patterns. hard, friable; brown fine For the most part, brown , reddish-brown, and concretions common ; few yellowish-red concretions occur in the surface fine roots; extremely acid. layer, though they are found at depth in some C 1 18-28" Va rie gated red (2 .5YR profiles. Gray and light gray concretions oc­ 4/8), weak red (lOR 4/3), cur in the C horizon , especially in the upper and reddish-yellow (5YR part. Colors suggest that concretions in the 6/8) silty clay loam ; mas­ deeper profile are more often low in iron sive; slightly hard , friable; oxides than those near the surface. Most con­ few light-gray fine concre­ cretions in the upper horizons are somewhat tions, few fine roots; ex­ flattened and platy, with a few being roughly tremely acid. spherical. In the deeper horizons, the concre­ C 2 28-32" Variegated weak red (lOR tions may be platy, spherical, or assume 4/3), reddish-yellow (5YR branching cylindrical forms much like reef 6/8), and strong brown coral. The spherical and platy forms are most (7.5YR 5/ 6) silty clay common. Total numbers of concretions are lo am; massive; sligh tl y greatest in the A and C horizons, and seem hard, friable; few brownish to be lowest in the B horizon. Nu mbers of coarse and very coarse con­ concretions decrease with increasing depth in cretions; few speckles of and below the C horizon, as a rule. gray (N 5/ ); extremely Sequences and thicknesses of hori zons and acid. the degree of hori zonation are not uniform C3 32-76" Variegated weak red (lOR among the bauxitic Latosols and related soils 4/3) and strong brown dominant in this association. As already indi­ (7.5YR 5/ 6) gritty silty cated, these soils comprise about half of the clay loam, appearing mot­ total area of the association. Perhaps 25 per tled because of light-gray cent of the soils in this half have the horizon (lOYR 7/ 1) fine to coarse sequence and thicknesses as described for the concretions ; yellowish-red one profile. Other soils either have been very coarse concretions eroded or have failed to reach the same degree common ; extremely acid. of horizon differentiation. Most of the soils C4 76-96" Var ie g ated wea k r e d , have thinner A horizons than the described strong brown, and black profile, some lack an A hori zon, and oth ers silty clay loam ; weak coarse seem to have lost both A and B horizons . platy structure apparently Some of these last-named soils have thin A retained from parent vol­ horizons which seem to be in process of for­ canic breccia; very strongly mation from former C horizons. Thus, about acid. three-fourths of the bauxitic Latosols and re­ (c) Additional Notes. The concretions in the lated soils in the association have profiles A horizon are large and tend .u be rough ly somewhat like but not identical with the one platy, with long axes ranging from 5 to 100 described near Ngardmau. Regardless of the mm. and short axes from 3 to 30 mm. All character of the profile, the Regolith is con­ seem to be vesicular, and some have shiny sistently deep, commonly exceeding 30 feet surfaces. Concretions are most abundant in and often reaching 50 feet. the surface layer and in the C horizon. Second in extent in the ' association are Soils of Palau - VESSEL AND SIMONSON 289

Latosols formed from volcanic Breccias but yards from a mangrove swamp . The vegeta­ lacking large numbers of concretions in the tion at the site consisted of coarse grasses and profile. These soils are identical with the low shrubs . dominant ones in the association of Latosols (b) Profile Description. from Breccias, described earlier. Some do have A 1 0-3" Reddish-brown (5YR 4/4) more concretions in the surface layer than silty clay loam; weak me­ typical, thus being intermediate in character dium gr,!-nular structure; between the bauxitic and nonbauxitic Latosols. soft, friable; many fine and Lithosols or lithosolic soils and Alluvial medium roots, few worm­ Soils comprise 10 per cent or less of the as­ holes and pinholes ; strong­ sociation. The nature and distribution ofthese lyacid. minor soils is similar in the two associations B 3-18" Yellowish-red (5YR 4/ 8) of Latosols from volcanic Breccias. silty clay; weak coarse and medium subangular blocky 3.Latosols from Tuffs (Ngardok Associa­ structure; slightly hard, tion) firm, slightly plastic, slight­ Although derived from different parent ma­ ly sticky; many fine roots; terials, the dominant soils of this association few pinholes; strongly closely resemble the Latosols formed from acid. volcanic Breccias, especially those low in C 18-42" Bedded deposit of weath­ concretions . On the whole, the soils from 1 ered tuffs in which the tuffs have thinner solums and slightly lower main layers are variegated permeability. Th ey have fewer concretions in weak red (lOR 4/2), red the profile and seem to be less weathered than (lOR 4/8), pale yellow the bauxitic Latosols from Breccias. Minor (2.5Y 7/ 4), and white components of the association are Alluvial (2.5Y 7/2) silty clay loam Soils and Regosols or regosolic soils. Total that is soft and friable. In ­ area of the association is 13 square miles, tercalated layers are red­ which is one-fifth that of the Latosols from dish-yellow (7.5YR 6/6) Breccias. Latosols from Tuffs occur only on silty clay that is hard, firm, Babelthuap, mainly in the northern half of slightly sticky, and slightly the island. plastic. The whole horizon The land surface of this soil association is has weak, very coarse platy highly dissected. Topography is mostly hilly structure inherited from to steep with local relief in many tens of feet. original deposit and is Ridge crests are commonly narrow but valleys strongly acid. are fairly broad with much filL Occasional C 42-60" Variegated weak red (lOY uplands have been dissected so as to resemble 4/2) and pale-yellow (2.5Y miniature Badlands, which are conspicuous 7/4) silt loam with very though small. fine white (2 .5Y 8/2) A profile description to represent the specks; massive; soft, very Latosols from Tuffs follows. friable; strongly acid. (a) Setting. The profile was described and Major differences among the Latosols from sampled south of the village of Aimeon g, Tuffs are in thickness and color of solum. west central Babelthuap. The site was a 25 Approximately half of these soils have solums per cent slope to the west in uplands about 112 or more feet thick. Another fourth have 100 feet above sea level and less than 100 solums between 1 and 112 feet in thickness . 290 PACIFIC SCIENCE, Vol. XII, October, 1958

The remainder have solurns which are less Regosols , which collectively comprise about than 1 foot thick. Colors range from low 20 per cent of its total area. Low Humic-Gley chromas and values of lOR hue to rather high soils occur in smooth uplands and on the figures of 7.5YR hue . The bulk of the soils lower parts of long slopes. Alluvial Soils are have colors of 2.5YR and 5YR hues . Some found along drainageways. The Regosols profiles have appreciable numbers of concre­ occupy the rare steep slopes . tions of various sizes in and on the surface Restricted in its occurrence on Babelthuap, layer. Concretions may be common but not this association has a total area of about 5 numerous. Thickness ofthe Regolith in which square miles. The main bodies are in the west the soils are formed is generally great, com­ central part of the island, with a few small monly falling between 40 and 100 feet. ones near the southern end . Minor components of this association, the Topography is dominantly undulating to Alluvial Soils and Regosols or regosolic soils, rolling, in contrast to the hilliness of the Lato­ form 10 to 15 per cent of its total area, The sols from Breccias and Tuffs. Slopes are long Alluvial Soils are similar to those in other and gentle. Local relief is measurable in feet associations dominated by Latosols . The Reg­ as a rule though it may reach tens of feet in a osols or regosolic soils are restricted to the few places. Latosolic soils from clays com­ steepest slopes and have about the same total prise the smoothest uplands on Babelthuap. area as Alluvial Soils. The Regosols or rego­ solie soils may have faint A horizons or . Chemical and Mineralogical Data on consist entirely of weathered Tuffs. Profiles Certain laboratory analyses have been made 4.Larosolic Soils .from Clays ( on samples of the major hori zons of several Association and Tabagaten Association) profiles from the Palau Islands . Data obtained Two soil groups are the main components will be given in full in a later publication, but of this association, all .of which are derived a few are given here to complement the from sedimentary clay beds . The more ex­ mo rphological observations. Table 1 gives tensive group consists of Red-Yellow Pod ­ data for exchangeable cations , pH, exchange zolic soils which approach Planosols in fine capacity, base saturation, a,nd organic matter texture and low permeability ofthe B horizon. for three profiles which represent the domi ­ They resemble the Colbert series formed from nant Latosols of the islands. Table 2 gives argillaceous limestones in the southeastern data on chemical and mineralogical compo­ . The B horizons are mainly sition on a section sampled for the study of yellowish -brown (lOYR hue ) silty clays. The bauxite ore in an area of bauxitic Latosols. second major group in the association con ­ The laboratory analyses reported in Table 1 sists of yellowish-red to red soils which seem were made in the Department of Soils and to be intermediate in character between Lato­ Agricultural Chemistry, ofH awaii, sols and Red-Yellow Podzolic soils. They and in the Soil Survey Laboratories, SCS, have some of the properties of each. The y U. S. Department of Agriculture. Methods may be more nearly related to the Davidson, used at the University ofHawaii are described Decatur, and similar series than to typical by Piper (1944), whereas those used in the Latosols or Red-Yellow Pod zolic soils. All Soil Survey Laboratories are described in U. S. gradati ons in profile exist between the yel­ Department ofAgriculture Circular 757 (Peech lowish-brown and red components of this et al.,·1947). association. Data given in Table 2 are from the labora­ Minor components of the association are tories of the U. S. Geological Survey. Stand­ Low Humic-Gley soils, Alluvial Soils, and ard methods for chemical analysis were used Soils of Palau - VESSEL AND SIMONSON 291

TABLE I EXCHANGEABLE CALCIUM AND MAGNESIUM, pH, EXCHANGE CAPACITY, BASE SATURATION, AND O RGANIC MA TTER IN T HREE LATOSOL PROFILES

CATION EXCHANGE- EXCHANGE- BASE ORGANIC DEPTH pH EXCH. ABL E ABLE SATURA - MATTER HORIZON CAPACITY CALCIUM MAGNESIUM TION

Inches m .e ./lOO g m .e ./lOO g m .e ./100 g Per cent Per cent

LATOSOL FROM BRECCIA * A I...... 0-12 5.6 22.4 8.3 1.8 45 5.20 B2I...... 12-26 5.6 15 .3 6.2 0.8 46 2.35 B22...... 26-33 5.8 16.7 6.6 0.7 44 2.45 B23 ...... 33- 39 6.2 20.3 7.8 0.5 41 1.44 C11 ...... : 39-60 6.2 13.9 7.6 0.5 58 0.50 C12 ...... 60-88 6.6 15.8 8.8 0.7 60 0.37

BAUXITIC LATOSOL FROM BRECCIA* AI...... 0-6 5.0 12.0 0.4 0.4 6 4.79 B2 ...... 6-18 5.0 8 .3 0. 1 0.4 7 2.38 CI...... 18-28 5.2 10 .1 0.3 0.5 4 0.98 C2 ...... 28-34 5.2 10 .2 0.3 0.6 10 0.85 C3 ...... 34-76 5.2 14 .3 0.2 0.3 4 0.64

LATOSOL FROM TUFFSt A ...... 0-3 36.7 7.1 5.7 37 B ...... 3-18 31.0 12 .2 2.8 50 C1 ...... 18-42 31.5 19 .6 1.8 69 C2 ...... 42- 60 30.7 17 .6 1.7 64

•Analyses through courte sy of Dr . G. D . Sherman, Chairman, Dep artment of Soils and Agricnltural Chemistry, Univer­ sity of . t Anal yses by E. M . Ro ller ., Soil Survey Laboratories, Soil Conservatio n Service, U. S. Dept . of Agriculture. in determining composition of samples given Latosols in the Palaus as there are elsewhere. in Table 2. The quantities of gibbsite and of The Latosols low or lacking in concretions silicate clay minerals were estimated by Gold­ seem to be much less strongly weathered than ich from differential thermal analyses and the are the bauxitic Latosols high in concretions . chemical analyses. Hematite and other min­ This inference is based on differences in erals were obtained by difference. morphology and on laboratory data given in Tables 1 and 2. 6. Comparisons of Soils in Palau Islands, The Latosols low or lacking in concretions Hawaii, and Puerto Rico have A horizons that are easily recognized be­ The Latosols in the Palaus have low de­ cause they are darker and more friable than grees ofhorizonation, diffuse horizon bound­ the Band C horizons. The B horizons are set aries, and common to numerous pinholes in apart because they are more plastic and less the profile. Morphologically, they are com­ friable than the C horizons. Differences in parable to Latosols observed by Simonson in plasticity are slight as indicated by dominant Hawaii, Puerto Rico, Ceylon, and Brazil. ranges in plastic index values (Casagrande, There are differences, however, among the 1932) of6 to 9 for the A horizons, 21 to 31 for 292 PACIFIC SCIENCE, Vol. XII, October, 1958

TABLE 2 C OMPOSITION OF L AYERS FROM AD EEP SECTION T HROUGH A B AUXITIC LATOSOL FRO M BRECCIA N EAR N GA RDM AU, BAB ELTHUAP *

LOSS ON SILICATE HEMATITE

DEPTH Si0 2 Al20 3 Fe20 3 T i0 2 IGNI- GIBBSITE CLAY AND OTHER TI ON MINERALS MIN ERALS

Inches Per cent Per cent Per cent Per cent Per cent Per cent Per cent Per cent

0- 20 ...... 0.98 44.12 25.55 1.38 26.14 66 2 32 20- 28 ...... 1.64 34.83 37.56 1.68 21.76 51 4 45 28-120...... 7.63 37.33 29.85 1.70 21.22 47 17 36 120-180 ...... 19.40 35.21 24.62 1.42 18.75 29 42 29

• Sampled by S. S. Goldich; hole 17, Taihei Area. Chemical analysis by Marie 1. Lindberg, U. S. Geological Survey. the B horizons, and 6 to 18 for the C horizons . those in Hawaii in low plasticity and sticki­

The CI horizon of the Latosol profile de­ ness despite high clay contents. Some Low scribed on Arakabesan has a plastic index of Humic Latosols in Hawaii are 80 per cent 31, which is in the common range for B clay but feel as though they were silty clay horizons. loams when worked between the fingers. Morphologically, the dominant Latosols in Field textures of Latosols in the Palaus seem the Palaus are like the Humic Larosols in marginal between silty clay loam and silt loam Hawaii, described by Cline (Cline et al., 1939). in the A I horizons and between silty clay and The profiles from breccias and tuffs are much silty clay loam in the B horizons. There is like the Humic Latosols in the character, se­ little reason to believe that the Latosols ofthe quence, and thickness of horizons. Both pro­ Palaus are lower in clay than those in Hawaii. files in the Palaus, however, are lower .in or­ Latosols, though high in clay, commonly ganic matter than Humic Latosols in Hawaii, have low shrinkage values upon drying and being more like the Low Humic Latosols in show little or no expansion upon wetting. this feature. The profile from tuffs has ex­ This behavior has been correlated with high change capacities rangin g from 31 to 37 liquid limit and low plastic index values. The milliequivalents per 100 grams which falls liquid limits for Latosols in the Palau Islands within the common range of 30 to 40 milli­ mostly range from 56 to 82. Lower values were equivalents for Humic Latosols in Hawaii. On foun d in the bauxitic Latosol, which had the other hand, the profile from breccia has liquid limits of 39 in the Al and 45 in the exchange capacities ranging from 14 to 22 lower C horizons. The plastic index ranges milliequivalents per 100 grams which parallels from 6 to 31, as was indicated in an earlier the range of 15 to 30 milliequivalents for Low paragraph. With in the continental United Humic Latosols. Ratios of exchangeable cal­ States liquid limit and plastic index values of cium to magnesium are much higher in the similar magnitude are found in the Davidson two profiles from the Palaus than they are in series (Fruhauf, 1946) and similar soils, which the Humic Latosols or Low Humic Latosols have been classified in the Reddi sh-Brown of Hawaii. All in all, the less weathered Lateritic group (Simonson, 1949). Although Larosols of the Palau Islands seem marginal similar to Latosols in a number of ways, the between the Low Humic Latosol and Humic Davidson profile has a much more distinct Latosol groups recognized in the Hawaiian and far less friable B horizon. Field descrip­ Islands. tions of the Latosols in the Palaus as well as The Latosols in the Palaus also resemble the liquid limit and plastic index values sug- Soils of Palau - VESSEL AND SIMONSON 293 gest that these soils lean somewhat in their Regosols, Alluvial Soils, and Organic Soils characteristics toward the Davidson series. These soils comprise about 6 per cent of Hence, they seem to be intermediate between the total land area of the Palaus but produce modal profiles for the Latosol group and the most of the food in the present agriculture. Reddish-Brown Lateritic soils. The one Regosol is a soil type widespread on The morphology and composition of the Pacific islands, known as Shioya sand. The bauxitic Latosols in the Palau Islands indicate Alluvial Soils are moderately fine-textured that they are more strongly weathered than and predominantly poorly drained, though the Humic Larosols and more nearly com­ they have a wide range in drainage conditions. parable in this respect to the Humic Fer­ Organic Soils consist ofpeats and mucks . The ruginous Latosols of Hawaii. Sesquioxides Alluvial Soils are slightly more extensive than have been concentrated to a high degree, either Shioya sand or the Organic Soils. partly in the form of concretions, in the bauxitic profiles (Table 2). Compared to the 1. Shioya Sand Haiku and Naiwa series in Hawaii (Cline et This soil type occupies raised beaches or al., 1939), the bauxitic profile is much lower low coastal terraces that are above wave ac­ in SiO zand TiO z, somewhat lower in Fez0 3' tion , principally in north Peleliu and at the and much higher in A1 z0 3• It is comparable north and south ends of Angaur. Additional in contents of SiOz and TiO z, lower in areas too small to be shown in Figure 2 occur FezOs, and higher in A1 z0 3 than the profiles along the northeastern coast of Babelthuap of Nipe clay described by Marbut (1930). and along the shores of Peleliu. Total area of Thus the concentration of sesguioxides, con­ Shioya sand in the islands is 2.7 square miles. sidering both aluminum and iron, is compar­ The profile of Shioya sand consists of a able in the bauxitic Latosol to that of Humic thin (2- 3 inches) gray (2.5Y 5/1) or grayish Ferruginous Latosols of Hawaii and to the brown (lOYR 5/2) A 1 horizon over a light Laterite soils of and Puerto Rico . The gray (2.5Y 7/2) C horizon. The whole profile chemical and mineralogical composition of consists of sand or fine sand, which may be the bauxitic profiles as indicated in Tables 1 replaced by gravel at depths of 2 to 4 feet. and 2 suggests that it is one of the end prod­ In most places, some coral fragments occur ucts of soil formation in the humid tropics . on the surface and throughout the profile. The Larosols of the Palau Islands clearly Consisting largely of coralline limestone frag­ represent two subdivisions ofthe broad group ments, Shioya sand is strongly calcareous. or suborder. The bauxitic soils are examples Much of the total area of Shioya sand has ofa strongly weathered group similar in many been planted to coconut palms, for which the ways to the Nipe clay of Cuba and Puerto soil is well suited . Minor crops that seem to Rico and to the Humic Ferruginous Latosols grow well are lemons, bananas, papayas, and ofHawaii. On the other hand, the profiles low . or lacking in concretions in the Palau Islands resemble the Humic Latosols of Hawaii in 2. Alluvial Soils some ways and the Low Humic Latosols in These soils occur along most streams and others . It may be that they should be con­ along many of the upland drainageways in sidered comparable to Humic Latosols in the the Palau Islands . Only the areas along the drier part of their climatic range . Dominant lower courses of principal streams can he Latosols of the Palau Islands also seem to shown, however, in Figure 2. The soils are all have a few properties in common with the slightly acid in reaction, and the dominant Reddish -Brown Lateritic group of the south­ ones are poorly drained . Less extensive are the eastern United States. well-drained soils and those intermediate in 294 PACIFIC SCIENCE, Vol. XII, October, 1958

drainage.. Total area of this associanon IS of the muck commonly ranges from 2 to 3);2 slightly more than 4 square miles . feet although it may be slightly less than 1 The dominant poorly-drained soils show foot thick in places. The muck is generally the effects of a water table at or near the sur­ underlain by gray silt, gray clay, or coral sand. face an important part of each year. A typical On Angaur, all of the mu ck is underlain by profile has a surface layer of brown (7.5YR phosph ate ore in the form of pellets. Approx­ 4/4) silty clay loam about 9 inches thick un­ imatel y 90 per cent of the total area oforganic derlain by gray (5Y 5/1) or olive-gray (5Y soils consists of muck. 4/ 2) silty clay mottled with brownish yellow Peat is less decayed than muck and is also (lOYR 6/8). Somewhere between 2);2 and 4 commonly lower in mineral matter. Plant feet this gives way ro dark -gray, nearly structures in the peat can be readily identified . impermeable clay free of mo ttles. Thedeposits range from 1 to 3);2 feet in thick­ Well-drained soils in this association are ness over limestone or phosphate ore. The commonly of similar texture but have brown areas of peat are approximately 10 per cent of surface layers grading downward into red, the total of Organic Soils. reddish brown, yellowish red, or yellowish The Organic Soils are especially valuable in brown. Mottled patterns and colors of5Y hue the Palau Islands because of their suitability are lacking in the well-drained soils. Soils for production. They produce high yields with drainage intermediate between the well­ of the crop , which is a major item in the diet drained and poorly drained ones are also of the people. intermediate in their morphology. The Alluvial Soils are adapted to most L ithosols, Stony Land, Rock Land, and M an­ crops that can be grown in the Palau Islands. grove Swamp In spite of the suitabilit y of the soils for This group comprises one soil association cultivation, however, very little of this associ­ and three miscellaneous land types. Col­ ation was being tilled in 1948. Most areas lectively, the group has a total area of 49 were idle, generally supporting tall coarse square miles, ranking second to the Latosols grasses which were replaced locally by poor from Breccias. Despite their large extent, forest . Taro was bein g grown on some howeve r, the Lithosols and miscellaneous patches of wet Alluvial Soils near villages. land types have little usefulness to agriculture. Other crops that seem to grow well on the Alluvial Soils are , bananas, coconuts, 1. Lithosols from Volcanic Rocks and pineapples. The main features of this association are the shallowness of soils, common occurrence 3. Muck and Peat of rock outcrops, and steep topography. Usu ­ These organic soils are ofmajor importance ally 6 to 15 inches deep over hard rock, the to present food production, despite their soil is dark, slightly acid, and commonly small total area. They occur as scattered indi­ marked by a faint and thin Al horizon. Rock vidual bodies, mostly along the northeast fragments are common on the surface and coast of Babelthuap and on the islands of throughout the profile. M assive rock out­ Angaur and Peleliu. Some bodies are too crops occur alon g ridge crests. The associa­ small to be shown in Figure 2. The total area tion has steep to hilly topography and is cov­ of organic soils is slightly less than 3 square ered by forest or savanna. The steepest areas miles . are mostly in forest, whereas the remainder is Muck consists of black, neutral to mildly covered by coarse grasses and low shrubs alkaline , highl y decom posed organic matter with scattered pandanus trees. Restricted to mixed with some mineral matter. Thickness Babelthuap and small nearby islands not Soils of Palau- VESSEL AND SIMONSON 295

shown in Figure 2, this association has a 4. Mangrove Swamp total area of 7 square miles. This miscellaneous land. type comprises wooded coastal areas that are periodically ' 2. Smooth Stony Land flooded by salt or brackish water because of Smooth stony land is largely covered by tides. The mangrove swamps occur along the limestone fragments or rubble, among which , on deltas, in embayments, and along are small quantities of fine earth, usually the lower reaches of the streams. The main phosphatic. For the most part, large lime­ areas border the coast of Babelthuap and the stone fragments are numerous enough on the eastern coast of Peleliu. Total area of man­ surface so that a person can easily step from grove swamp in the Palau Islands is slightly stone to stone. Pockets of soil material are more than 14 square miles. commonly tiny but a few are as big as 1/100th of an . The soil material is dark brown, AGRICULTURE friable, silt loam to loamy coarse sand and may reach depths of 10 inches in somepock­ Agricultural prod uction in the Palau Is­ ets. As the name of the land type sugges ts, lands in 1948 was of a subsistence type. The smooth stony land is nearly level or very crops being grown were used as food for the gently sloping . It forms important parts of families prod ucing them . The main food Angaur and Peleliu and has a total area of crops were taro , cassava, and sweet potatoes. 2Y2 square miles. Production of these crops was by hand til­ Most areas of smooth stony land are cov­ lage, a clear index to the prevailing level of ered by brush and small trees. Small clearings, agricultural technology. usually a fraction of an acre in size, are made here and there in the forest for the planting Crops of cassava, sweet potatoes, bananas, and pa­ payas. These may be planted separately ?r in Taro (Colocasia esculentai, which yields an mixtures more often the latter. Individual edible tuber, is prod uced mainly on Organic clearings' are usually abandoned to the forest Soils and poorly-drained Alluvial Soils in the again after a few crops have been produced. Palaus. It is also grown to a limited extent on Latosols, preferably on lower slopes where 3. Limestone Outcrops some seepage can be expected. Commonly This form of rock land, as its name sug­ grown with taro but on the ou ter margin of gests, comprises exposures of coralline lime­ the paddies is a coarser plant (Cyrtosperma stone and rubble with little or no fine earth. chamissonis) which prod uces a large tuber The surface of the limestone is commonly eaten when the taro crop fails. Several large pitted and pinnacled. Some soil material is "elephant ear" varieties, identified by Fo~­ present in small pockets and in crevi.ces, gen­ berg6 as Xanthosoma violacea and Alocasi« erally in handfuls. Present vegetation con­ macrorrhiza, are grown occasionally on soils sists of small trees and shrubs. Limestone of the uplands. Like the Cyrtosperma in the outcrop forms the islands of Urukthapel, Eil paddies, these are also eaten only during se­ Malk, and Ngergoe (all of which lie between vere food shortages. Koror and Peleliu and are not shown in Fig­ The second crop of importance is cassava ure 2) ; parts of Anguar, Auluptagel, Koror, (Manihot utilissima), called "tapico" by the and Peleliu ; and the southern tip of Babel­ Palauans . It commonly supplements and may ~n­ thuap. It also forms a number of small replace taro in the diet. The crop was intro­ named islands between Koror and Peleliu. duced during German ownership of the is- This land type has a total area of 24 square miles, none of which is inhabited. 6 Person al com municarion, April 9, 1951. 296 PACIFIC SCIENCE, Vol. XII, October, 1958 lands . Improved varieties with higher starch been used in the past. Cultivation of the soil contents were brought in by the Japanese is by means ofa four-pronged hoe introduced who raised cassava for export. The crop by the Japanese. Tillage consists of stirring grows best during the driest season of the of the soil to shallow depths . Subsequently, year, when fungus diseases are the least active. slips or seeds are planted . Vegetative repro­ It is grown mainly on the Latosols but to some duction by means of slips is the more com­ extent on Alluvial Soils. mon practice. Third in importance among food crops are Garden patches on Latosols and some on sweet potatoes, which were introduced by the Alluvial Soils and smooth stony land are usu­ Spaniards. Sweet potatoes are produced by ally planted to cassava or sweet potatoes. the same methods as cassava. They are grown Some gardens may have both crops growing on the Latosols, some Alluvial Soils, and at the same time, plus scattered individual Shioya sand . plants of other crop species. A single garden may be used for cassava or sweet potatoes Minor crops are coconuts, sugar cane, Ta­ exclusively, or the two may be alternated. hitian chestnuts, breadfruit, jakfruit, pine­ After the plants become ripe they are har­ apples, oranges, mangoes, papayas, sauersop , vested a few at a time, as needed by the family. and pandanus. Coconut plantations were rela­ The patch is replanted with cassava or sweet tively important at one time but the invasion potatoes after all of one crop has been har­ of the rhinoceros beetle has reduced produc­ vested. This process is then repeated until tion to very low levels and forced abandon­ yields in that one garden patch begin to drop. ment of most groves. Sugar cane, pineapples, Once the yields have fallen, the patch is and papayas are grown as scattered plants in abandoned and a new one is cleared either by a patch of cassava, sweet potatoes, or both. fire or knife. The whole process is then re­ Orange and mango trees producing food are peated once more in the new clearing. commonly lone plants in or near the villages, Continuous growing of taro is common whereas chestnuts, breadfruit, jakfruit, sauer­ practice on the Organic Soils and the poorly sop, and pandanus grow wild in the savannas drained Alluvial Soils. The planting, weeding, and . and harvesting of taro are the responsibility of the women in the families, who also own the Methods taro paddies. The paddies used by a single Shifting cultivation is the general practice family are divided into a number of segments in the production of food crops on the Lato­ and planted so that one segment is always sols of the Palau Islands. Most areas of Lato­ ready for harvest . Thus, the plants in different sols readily accessible to villages are now in segments of one paddy may be in all stages savanna vegetation. Burning of the grass is of growth from slips that have just been therefore the first step in clearing a garden placed into the soil to ripe plants awaiting patch. A few areas ofLarosols as well as most harvest . After all of the plants in a given seg­ of the smooth stony land is in forest or brush. ment have been harvested, that segment is Clearing of a garden then requires the cutting again replanted while harvest begins in of saplings , vines, and brush , usually done another part of the paddy. Taro paddies with a large knife or machete. After the sa­ commonly receive more attention than do vanna is burned or the forest cut, the soil is upland gardens because of their greater im­ stirred with a simple hoe and crops are planted. portance in food production. All tillage, planting, and harvesting in the Efforts are made by the Palauans to incor­ Palau Islands are done by hand . No draft ani­ porate decayed leaves and grass as well as mals were on the islands in 1948 nor had they wood ashes into the soils, especially in taro Soils of Palau - VESSEL AND SIMONSON 297

paddies. Commercial , insecticides, imp ose certain limitations on agricultural and the like, have not been available in the pro duction even with the best technology Palau Islands. Methods used by the Palauans available. The small total area of the Palaus in to maintain and imp rove their soils as well as itself restricts opportunities for the large scale methods of tillage, planting , and harvestin g agriculture in which sugar cane, cacao, and are all common elements of a simple agri­ similar crops are commonly produced . Fur­ cultural technology. thermore, the major soil associations of the Palau Islands are dominantly hilly to steep. Potentialities Individual areas with level, undulating, or rolling topography are small. Proportions of Improvements in agricultural technology the major soil associations with topography woul d permit increased food production from favorable for mechanization are therefore the soils of th e Palau Islands . Some improve­ small. As a consequence, full use of the to ols ments are possible within existing patterns of of soil management available in a modern in­ operation. For example, better crop varieties, 'dustrial society does not promise to become commercial fertilizers and insecticides, and feasible in the Palaus . Something less than simple machinery such as hand cultivators full use of those tools is more likely to be coul d be used in the present agriculture . Cer­ appropriate. Possibilities for commercial agri­ tain shifts are thus possible without major cultural production seem limited, all in all; changes in the agricultural arts. Such shifts but there is opportunity for greater food would mean appreciable increases in food production through improvements in soil use production, without realization of the full and management. potentials of the soils. To achieve full potential production from REFER ENCES - soils of the Palaus, major changes from the present agricultural technology would be re­ BALDWIN, M ARK , CHARLES E. K ELLOGG, and quired. What the potential may be can be JAM ES THORP . 1938. Soil classification. IN inferred from current yields on Humiclatosols Soils and Men. U. S. Dept. Agr., Yearbook and low Humic latosols of Hawaii, soils for 1938. Pp. 979-1001. which are comparable to those of the Palau CASAGRANDE, ARTHUR. 1932. Research on Islands. Yields of 8 to 10 tons of sugar per the Atterberg limits of soils. Public Roads acre are common on the l atosols of Hawaii 13: 121-130. (Cline et al., 1939), where soil management CLINE, M. G ., et al. 1939. Soil Survey of the includes heavy fertilization , irrigation, mech ­ of Hawaii. U. S. Dept. Agr., anization, and many more ofthe management No. 25. elements available to agriculture in a modern CORWIN, GILBERT . 1951. "The Petrology and industrial society. The findings of modern Structure of the Palau Volcanic Island s." science and the products of mo dern industry Unpublished thesis , 266 pp . University of are widely used for crop pro duction on Lato­ M innesota. sols in Hawaii. Thus, the level of agricultural FOSBERG, F. R. 1946. Botanical Report on Mi­ technology is markedl y different from the cronesia. U. S. Commercial Co., typescript one prevailin g in the Palau Islan ds. microfilm , 350 pp . library of . Experience in soil lise and management FRUHAUF, B. 1946. A study of lateritic soils. does not seem directly transferable from Ha­ Res. Bd. Proc. 26: 579-593. waii to the Palaus, though major soils in the K ELLOGG, C. E. 1949. Preliminary sugges­ two island groups are the same. The total tions for the classification and nomencla­ land area and the topography of the Palaus ture of great soil groups in tropical and 298 PACIFIC SCIENCE, Vol. XII, October, 1958

equatorial . Comm, Bur. Soil Sci. and Sci. Congo (, P. I.) Proc. (In press.) Tech ., Commun. 46: 76-85. SOIL SURVEY STAFF. 1951. Soil Survey Manual. M ARBUT, C. F. 1930. Morphology oflaterites. U. S. Dept. Agr. Handbook 18. Second Internatl. Congo SoilSci. Proc. 5: 72-79. TAYAMA, RISABURO. 1953. Geomorphology, PEECH, M., 1. T. ALEXANDER, 1. A. DEAN, Geology, and Coral Reefs of Palau Islands. and ]. F. REED. 1947. Methods of SoilA naly­ Taihoku Imp. Univ ., Inst, Geol. and Pale­ sisfor Soil-Fertility Investigations. U . S. Dept. ontol. Faculty Sci. Contrib. 18. 67 pp. Agr. Cir. 757. [Japanese.] PIPER, C. S. 1944. Soil and Plant Analysis. U. S.D EPARTMENT OF ARMY, OFFI CE OF Interscience Publishers , N . Y. 368 pp . CHIEF OF ENGINE ERS. 1956. M ilitary Ge­ SIMONSON, Roy W. 1949. Genesis and classi­ ology of Palau Islands, Caroline Islands, Pp. fication of Red-Yellow Podzolic soils. Soil 89-133. [Processed.] Sci. Soc. Amer. Proc. 14: 316-319. U. S.D EPARTMENTOF COMME RCE, WEATHER --- 1953. Soil classification and mapping BUREAU. 1953. L ocal Climatological Data, in North Pacific Islands . Eighth Pan-Pacific Koror Islands, Pacific.