the relationship between soil and population density

8/7/2019 The Relationship between Soil and Population Density

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MOHR: Soil and Population Densitynutmeg and mace. Curiously enough, all t heseisla nds are volcanic. Buru, Ceram and Misoolare much larger, but not volcanic , and these thecompany ignored.In the Sm a ll Sunda Islands group we have Balidominated by Mount Batur, Lombok by MountRinjani . These two volcanoes have providedtheir respective territories with first-rate juvenilesoil, on which has arisen a dense, prosperous andhighly cu ltivated population. Sumba, on theother hand, has had ver y little volcanic influence ,its dreary , desert-li ke wastes being composedchiefly of bare, calcareous rocks. All there is ofgood soil is washed or blown from the highlandsin to the lowla nds a nd hence we find , besides the

254ver y poor , utterl y deserted areas mentioneda bove, also fairl y prosperous plains.

The above may be s ummarized as follows : It is true that afall of rain may be a bl ess ing to an agricultural ar parchedfrom drought , but it is eq ually true that in the tropical zonein the narrower sense of the term - the zone in which theNetherland s Indies are situ ated - too much rain is badand . further, that abundant rainfall is t he ca use of co ntinually increasin g impoverishment of the soil. The only regenera tion of the so il th at spells radical improvement is tha tproduced by volcanoes. \Vith out activ e volcanoes thefulure ca n only mean retrogress ion. But re trogress ion maybe greatly retarded and counteracted by human action.Thi s last is the splendid task of the science of agriculture.Much has already been achieve d along thi s line, a ndprobably much m ore w ill be ac hieve d in the future.

THE RELATION BET\\TEEN SOIL AND POPULATIONDENSITY IN THE NETHERLANDS INDIES

byE. C. J. MOHR, Ph.D.*

E xtension A gronomist, Colonial Institute of Am sterdam !' late Dir ector, 9en eralA gricultural E xperim ent S lalion , Builenzorg; lale .Geol9gls1 and . d ~ l o g t , Depl.of A griculture, BILiten zorg; Sp ecial Professor of S OLI Sc tence, Unwer stty of Utrecht.If we wi sh to make a stud y of th e rela tion between popula tion density a nd soil , we must confin e ourselves to regions where th e distributionis not dependent , or at leas t not altoge ther depend ent, on mea ns of subsista nce which a reenti re ly, or a lmost entirely , independent of th ena tur e of th e so il , such as tr ade (imp ort -tr ade,export -t rade, tr ansit-t rade); mining ; industr ybased on mined raw materials, or on materialsbrought from a dist ance a nd th e like. \IIIe mustconfine our selves , then, to specifically agriw ituralareas, where agric'u/t lIYe (tnd /lOrticltitn re andf orestry are t.he 01l1y, or at least by f or th e 1II0st i l/1.-portant, mealls of ea rnin g a living.As the Netherlands Indies is still a t th e presenttime largely an ag ricultur a l region of this kind ,it is a pa rticularl y suita ble obj ect of stud y inconnection with our problem. Thanks to theexce llent Ce nsus, t aken in 1930,' we know fa irl ywe ll wha t th e popula tion is in different parts ofth e ar chipelago. Th ese fi gures show th at th edensity va ries from less than one to mor e than athousa nd souls per km2 In oth er words th edifferences ar e enormous. Hence to tr eat th ewhole arch ipelago as if it were a uni form areaa nd could be s tudied as such is out of the q ues

tion.For, whi le th e ave rage for th e whole territoryis put at 31.89, we find Java and Mad ura run ning up to 316.11 and on th e oth er hand, theOu ter Provin ces fa lling to 10.73 - a surpri singcontrast ind eed. And within th e Out er Provinces th emselves we meet with very grea t dif ferences. For Ba li a nd Lombo k th e figure is175.18, for Celebes 22.39 , for Sum a tra 17.43 andth en aga in there is Borneo with 4 .02 and N ewGuinea with 0.73. H ence we wi ll consider th eislands and islands groups separately first andth en finally compare these very greatly va ryingterritories with each oth er.* Reprinted from Comptes RelldllS dll Congres 11ller lla-l1'o1lal de Gengraphie, Amsterdam, 1938, Tome Deuxie me,Sect ion Il I e. pp . 4;8-493 ( 1938) .1 Th e Report is being published in a series of v olum es, thefiTst of whi ch a ppea red in 1933 .

1. JAVA . If we examine th e la rge volumesconta ining th e Ce nsus Ret urn s for 1930! we fin dthat t o eac h of it s several pa rts dealing WIthWest J ava (I) , Ce ntr a l J ava (II) a nd East Ja vaplus Madura (III) is appended a map . on \ .hlchth e country is divided into admil1lstratlOna lunits ca lled di stri cts and coloured in eight shad esindica ting popula tion density . Tho se who donot know Ja va and it s so il will lea rn little fr? mtho se map s and see nothing but colours showll1gthat the popula tion is very dense in and a r o u ~ d the big c iti es, and further, th a t there .a re ~ r t a l l 1 districts where there ar e less than 75 ll1habltantsper km ' ; man y where th ere ar e be twe en 150 and500 and severa l with between 500 and 1000 alt h o ~ h they do not include a la rge cit y. Bu t assoon as we beg in to notice th e topography andgeology of Java, th e climate and th e SOl i t ypes ofth e different pa rt s of th e island, th ese maps begin to take on a grea ter significa nce for us. .In general we ma y assume that where the ~ O l l is good a nd ferti le, agricultura l crops wlll bringin a rich harves t with th e result that th e population which cultivated th em is not only satisfiedwith past success, bu t is , further, insP.ired. tobring more and more land under cultlvatlOn .If on the oth er hand the ha rves t is poor, th etenuency will be to cultivate more int ensivelyor to move away to another place where moresuccess may be anticipated.On th e island of J ava - and as we shall seelat er, this really app lies to the whole of th eNeth erlands Indies - experience has shown thatthe 'most f ertile soil types are related to volcanoes.\II.Ie find th em on th eir slopes, at their base andin th e basins of rivers, the wa ter and silt ofwhich comes from a volcano. But such volcanoesmust be recellt must have been active within th emost recent ie ological period or be active still.Old volcanoes are covered with mor e or lessworn-out, se nile soil, which, sti ll cultivable andphysica lly good for vegetation, is very muchimpoverished . On and round a recent volcanoth e so il is usually composed of or derived fromvo lca nic ash es and sand, in fact often contains

255lit t le else as yet in the way of newly form ed so ilmaterial. Such juvenile volcanic ash-soi ls ar eextraordinary rich. Is it any wonder, then, thatpeop le risk the dangers of anothe r eruption andeagerly choose suc h land to settle on?Now st eep slopes are a lways more difficult tobring und er cu ltivation and a lso to live on thanplains; it is th erefore that th e more level riverlowlands at the foot of the volcanoes ar e preferred to th eir slopes. Moreover as a rul e th eplains get mor e sun shine ; this is ~ matter f direct importance to the vegetation but it is a lsoindirectly significa nt, for the r ~ o n that theferti lity of th e s oil is promoted thereby .Th e .following districts in Wes t Java (seeta ble) llius trate the abo ve . Th e most juv enile

Volcanoes Di stricts o n slopes PopulationGedeh ( 1) Tjibadak 296(2) Tjiawi 3 12(3) Pat je t 292(4) Tjibeber 315

(5) Sukabumi 562'Tan gkub a n (6) Tjika lan gwet a n 198Pr a hu (7) Purwa ka rt a 189(8) Sega la hera ng 191(9) Lemba ng 441( 10) Tjima hi 371*Guntur (I I) Leles 452( 12) T rago ng 514Ga lungg ung ( 13) Ga ru t 552*

(14) Tas ikma laya 637'( IS ) Tji aw i 476( 16) Sin gapa rna 3 17Tj erim ai ( 17) M adj a le ngka 530*( 18) R ad jaga luh 520( 19) Tjilim us 368(20) Kuningan 354(2 I) Te laga 437

MOHR: Soil and Population Densityfactor. Witness the following facts: Slawi andTegal derive the!r fertility from the young vol cano, Siamat, vIa th e riv er Ka li Gung; Purbohnggo and Sukaradja lie on that same mountain's south eastern spu r ; K lat en has the fin estMe:api-soil, Tulungagung has the same fine soilderived from K lut and Probolinggo gets it fromthe La mongan volcano. On th e oth er handAmbarawa and Sa lati ga are on older volcanicsoi l ; Blora ,. Tj epuh , Tuban , Bodjonegoro andLamongan 111 a tertiary area , far aw ay from theneare st v?lcano. At Paree the soil is composedof Klut-eJecta; these ar e not fin e as in Tulungagung hmve.ve:, bu t .more sand y a nd stony. Not

o eas.y to lrnga te e Ith e r, a nd , besides, ra th er tooJuvend e. Hence the fi gnre f or each district can beRemark s

The Gede h-soils a re no longer fu lly juv enile . The dis -tricts (I) . (3) a nd (4 ) include a lso man y old er no n-Gedeh-sails. (5 ). even if th e capita l is excluded . ishigh on account of the vici nit y of this large town(vegeta ble a nd flower culture).Th e nor t hern s lopes of th e T a ngkuban P rahu a re a l-ready rather senile; rejuv enescences have tak en placeto th e So uth in the dir ec ti on of (9) a nd ( 10) . (9 ) li eshigher . With pat a t ae and vege table cu lture; ( 10) hasmore plallls and , moreover, has the ga rriso n as a noutl e t.

o h dis tricts have sawahs wi th splendid yields i be-Sides fish culture .(13) an d (14) have m ore pla ins t han (IS) and (16).(16) lies high a nd is accide nt ed. in cl ud es a lso no n-Galun ggung-soils , but all so ils a re vo lcanic .( 17) a nd ( 18) have more lowla nds. Bes ides rice. sugaris already culli va ted here. Bu t (17). li ke ( 19) . (20)and (21), a lread y includes some bad tert iary areas.

,d The se figures for the dlstn cts have been recalculated aft er deduc tlOn of the popula tion of th e municipalities and tow nsan naturally the area of these . '

soils, not even turned brown ye t, a re to be found111 (9) to (14); most weath er-worn and lixi v iated(by heavy rain s !) ar e tho se of (6) to (8). Note\ ~ o . r t h y ar e the corresponding popu lation den sItIes of th e l : l r r o u . ~ d i n g ~ of th e larger towns suchas SU.ka bUI:ll, !Jlmahl , Garut, Madja lengka ,to whIch TJandJur (500) Buitenzorg (577) andMr. Cornelis (550) may be added. Such a correspondence might indicate that the said figureswere du e more to the vicinity of a large town .But tha t would mean that in Central and Ea stJava and e lsewhere, too, th e sam e figures wouldbe found in th e neighbourhood of large towns.ThI S IS, however, by no means the case. Takethe following districts, for instance (capita lsexcluded):

Slawi 797 Ambarawa 368Te ga l 1052 Sala t iga 387Pe ka la ngan 148 6 Ba yal ali 360Purba lingga 7 I 2 Sragen 353Suka radj a 746 Bla ra 305Kebumen 795 Tj epuh 236Purworedjo 837 Badjanegara 232Kla ten 1023 Tuban 312Kudus 900 Lamonga n 341Tulun gag un g 770 Paree 335Probalinggo 710 Bondowoso 278.Although, as we have seen, th e fact that itcontains a fairl y large town , does influence th eden sity of the population of the district , yet inJava the nature of the soil is a more important

explained O ~ t th e. ground of tIle nat ure of the soilcombtned wtth cltm attc coudi tio1ls. Bu t th ere areexceptional cases too. For ins tance : the highfigure f ~ r P e k ~ l o n a n and th e surroundingcountry IS certa1l11y du e to the batik indu str yloca ted .there, a nd tha t of Kudu s to the na ti veclgaret l n d u t r y . Mor e significan t sti ll in thisconnectlOn IS t h ~ t b t w e ~ n .S lawi and Te galt ~ e r e bes th e Adl\verno dIstrict, complet ely irri gat ed bu t n ot includin g a single large town .The populatlOn denSIty th ere is 163& - th e highest of any country di strict in the NetherlandsIndies. Without S lamat's good' gifts such anum erous population would be out of que stionthere .As a matter of fact these good gifts of Siamat's ,and also tho se of the Dicng volcanoes were car ried southwards with th e wa'ters of ' the riverSeray u to the sea . . And th e sea gav e them ba ckto th e la nd in th e form of sand and dun es alongthe coast from Maos on far to th e Eas tward .Further on oth er rivers worked to th e s ame endwith th e result that a long the who le South coastfrom Maos t o Djocja a ll th e coastal districtsshow an average den sity of between 500 and900. Eastward and westward Siamat couldhardly shed i t ~ beneficence because of the presence of older hIghlands. Hence we find districtsth ere with only from 300 to 400 inha bita nts perkm. 'Th e country surrounding th e l\IIerapi is an -


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256MOA R: Soil and Population Densityoth er remarkable case. This vo lca no, t he lasteru pt ion of which was only seven years ago, hasrecently sent its ashes, sa nd a nd sto nes more.especia lly in a weste rly to sout h-westerly dIrection' to t he No rth lies G unung Merbab u,barr ing th e way and to th e .ast a rin gwa ll , o,:",eciwh ich only light , powdered e c t ~ can be carneto cover t he land as aerial deposits. Round th efoot run the rive rs which sort ~ u t th e y o g fertile soil-ingred ient s a nd deposit .th em aga ll1as a lluvia l types of soi l st ill more fertile tha n t hatfou nd on th e mounta in slopes ; to th e 'West run s

bacco culture in the Native Stat es) . On th eeas t ern banks of th e rivers Kali Denkeng a ndKa li Solo th e density suddenly drops from moretha n 800 to less than 50.0 - much less ash fromthe Merapi reached thi S a rea. Nor oes t hedensity exceed 500 in th e highla nds to th e N ~ r tThe proximity of the la rge \ ~ n o ~ u a ~ a r t a does not see m to influence the situatIO n ; l t ~ e ~ does Magelang affect th e surr oundll1g countl y,a ll depe nds on th e vo lcanic prod ucts - n th eso il ; and rivers act as fronti erlines even 111 t hematter of density of popula tIOn.

I N D I ~ c H E

_ F IGURE 71 (see p. 256 ) -

th e Progo to the South the Opak, to th e Eastthe n g an d So lo rivers. T o the N o ~ t h t here is non e. And now for t he comparat ivedensity of th e popul at ion (see Fig. 71).To th e South and So uth West, where th eyo ungest sand and block str ea ms came ~ see adensity ra nging between 543 and 653 (1), moreto th e South on th e allu v ia l soi l, from 800 to900' westwards from here , across the Pro gov l l ~ 378 to 500, and t hen a long th e coast th efi gures r ise once more. On th e eas tern slopest he density is 600, abov e these 400 a nd on th esad dle between Merapi and ] \ r a wherethere is extensive forest reserve which moreove r t he yo ungest ashes did not reac h , only 245.At th e foot th e figures rise to 800 or eve n tomore than 1000 (K ia ten , the centr e of th e to-

Typica l too in thi s conn ection is the course ofthe river 'Bra;llas, especia lly th ere. wh ere, nearBlitar, th e ejec ta from Klut enter ItS. waters, .tobe sorted or mixed a nd the n. deposited aga ll1 .The ex tensive higher portIOns of Sn; ngat,Ngadi luweh and Pa ree are as ye t too a nd onaccount of excess ive sa nd , gravel a nd sto nes tobring the ave rage higher th an abo ut 400. Alongt he Bra nt as the fi gure is higher (T ulung Agung(770*),' Ked iri (490*), bu t th en come Pa p: r(610)' Warudjajeng (721) ; Ke rtosono (609. ),D' on;bang (672*), Mod joag ung (637); M o ~ k ~ r t o (556*), Kr ian (703) , Taman (617), SI-, An asterisk means that. as mentioned e f r ~ . the ~ g ~ { ~ in Question has been arrived a.t after the P d 9 P u . a ~ H h n an b e ~ n area of the (main lown) cap it al of the lst nc avesubtracted from the total popula tion and th e total area.

257doardjo (455), Modjoasri (541), Porong (696),Gempol (656), Bangil (479*). Bot h to th e Northa nd to the South of this series th e fi gures are below (400), and in th e ter tiary marls of th e adjace nt Gunung Kendeng eve n below 200.Above we spoke of th e bene fi cent effect ofvo lcanoes. Bu t not a ll volcanoes are the sa me.T he above menti oned ones all provide basicrock, with much lime, magnes ia, iron, pot assium,phosphoric acid in them. But vo lca noes oftenproduce acid rocks containing much silicic acid,little lim e and little iron. The soil derived fromsuch rocks is in general phys ically less loose andoften very sticky and heavy; chem ica lly less rich,too. In J ava th ere is only one reg ion in whichsuch rocks occur to any grea t ex tent, name lyBantam. Where they predominate the fer tilityof the so il, hence the ag ricultura l ret urn s, hencethe density of th e pop ulation is natura lly lessthan it would have been if the rocks had been oft he sa me nat ure as those derived from Galunggung or Siamat or Merapi or Klut. The following districts illustrate this: Pamarayan 291 ,Rankasbitung 173, Lebak 79, Parungkudjang66, Tjilangkahan 47 a nd Tjibaliyung 20 - thi slast being th e lowest figure for Java.The poverty of th e soil in these las t mentioneddis tri cts is due partly to the fac t that the bleachedBantam tuffs are a lready primarily poor in plantfood, and partly to the climate. There is a yea rlyra infa ll here of between 3 a nd 5 m a nd thi s leachesthe soil thoroughly. With StIch a rainfall the soilmust be very jllvenile to prod1ice enough food for thepopulation, a nd since there are few instances of

MOAR: Soil and Population Densitythi s reduction of rainfa ll must not go too far .I t must not Rroceed to the point where there isinsufficient moistur e for th e food crops, so thatth ese might consequentl y suffer a nd fin a lly diefrom drought .In ord er to corr ec t unfavo urable conditionsin regard t o water supply, th e culti va t or, in th epresent case th e na ti ve of th e Netherla nds Indiesa pplies irrigation. Th e table below will serveto mak e clearer the effec ts of this irriga tion :Here we note:in (1) . There a re two reasons for the fac t thatit is imp ossible to use irrigat ion as a mea ns forproviding the lack ing food crops.a. Th e la nd is co nvex in a ll dir ections consisting of ridges and hillocks, on which irrigationwater ca nnot be brought . For exa mpl es fromBantam see above. Lime platea ux in So uthPri a nger, na mely, Djampangkulon 64, Sind an barang 42, Bungbulang 57, Pa meungpeuk 55 ,Karangnunggal 88, Tjikatomas 92, Tjidjulang79, fall und er the sam e head . Also Tjilatjap175 , one of th e lowest averages in Ce ntr a l J ava,and Pan ggul 139 in South Kediri as well as th eSoutheastern part of Gent eng 111, a lm ost uninh ab ited.b. Water ca n be brought up, but thi s wat erits elf comes from areas where the soil is poora nd th erefore it cont ai ns little plant food or non e.A case of thi s kind hardl y eve r occ urs in Java ,bu t in the Out er Provinces (Sumatra , Borneoa nd New G uinea ) it is fairl y common . Conc1usion: irriga tion is useless.In (2) . If irrigation is app lied in areas where

In general In ge neral In genera l100 mu ch rain water sufficient rain water too lillie rain waterSo il grows poorer soil grows poor in the long run; some vegetat ion suffers and finally diesyears there is drought fr om drought

Irrigati on to prov ide pIa,,' food Irrigation to i,lSure Irrigation to provide wa tersuccessful harvestim possible possible effect va riable impossib le possi ble

pop ul a tion sparse pop ulation fairly populati on density medium population sparse pop ul ati on den seto very dense

( I ) (2)

such ju venile soi l in t he world , it is safe to saythat areas where heavy rain falls througil01tt theyea1 are as a mle b1tt sparse ly pop1llated. E vensoil which was originally very rich, on the slopesof a volcano for inst ance, must, und er suchclimatic circumstances, decrease in ferti lit y sogrea tly , as soon as the virile stage is passed andit has become mor e or less senile, that the population decreases too. Th e northern slopes ofthe Dieng highla nds are a case in point : on th eseslopes and adjacent to th e very densely populatedlowla nds of Pekalongan (lvViradessa (979) ,Pekalonga n (1486*), Batang (601 *), K edun gwuni (929)) lie Doro with 142, Bandar with 246,Bawang with 238, and th e yea rly rainfall th ereis 3Y. to 7 m! Th e north ern slopes of Tangkuban Prahu a lready menti oned in t he firsttable show population density figures below 200on account ' of thi s same excessive rainfall.We may say, then, that the above italicizedline may be expand ed as follows: Within certainlimits , the less rainfall the more fertile the soil andthe denser the population. Thi s fertility is moresta ble , less ap t to be a passing ph ase. Naturally

(3)to very dense

(4 ) (5 )th e so il is worn out and poor as a result of muchrainfa ll a nd th e water introd uced is derived fromyo ung highlands (volcanic peaks), very greatsuccess is so metim es ac hieved . Instances of thi sare: Buitenzorg 577*, Sukabumi 562*, Tasikmalaya 637*, Madyalengka 530*, e tc .In (3) . If the soil is alr eady old and more orless worn out, th e cas e is in line with tha t in dicated und er (2) and then irrigation is certai nl ybeneficent, especia lly as a means of suppl y ingplant food, eve n when the rainfa ll is not ove r 4 ma nnu a lly but abo ut 2 m. In regions where th eave rag e yearly rainfall is sufficie nt in th e lon grun bu t an occasional yea r of drought has to bereckon ed with, irriga tion is und oubt edly ablessing as a defense aga inst crop-fa ilure, in thatit ensures a sa tisfactory wat er supply anyhow .These conditions ar e found in many districtswhere th e population densit y figures a re between250 and 450 .In (4). It is impossibl e to crea te a watersupply where th ere simply is no wa ter avai lable.But this condi t ion of things is not found a nywhere in Java. In the mos t arid parts of t he


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MOHR: Soil and Population Densityisland th ere is an average rainfall of 800 mm .There are years occasionally when it is only 400mm or even a little less, bu t these are exceptions.Ye t there are parts of Java in th e extremeNorth East of th e island which cannot be irrigated, or rather, where there is no irrigationand where no rain falls for six, or sometimeseight months. One of these is the Sumberwarudistrict, where the population is 87 per km2, although th e soil would surely be fertile, if onlythere were water. On the Small Sunda Islandsare areas of this character, which are more ar idst ill and more thinly populated.In (5). In cases where it is possible, thanksto high mountains in the hinterland, to bringirrigation water to a relative ly arid region wherethe soil is rich we find the greatest fe rtility.Along the North Coast of East Java, where therainfall is less than l Y, met res, it is irrigation,a nd the very extensive cultivation of sugar,which this has mad e feasible, which are respons ible for the density of the population in Pasuruan(656*), Probolinggo (710*), and Sitobondo (510*).Back of these and at a slightly higher a ltitudeare districts which are not irrigable and which insp ite of the fact that they get a little more rain ,show a very much lower ave rage populationdensity. There are: Tengger (Pas.) 149, Tengger (Prob.) 127, Gading 130, Pradjekan 115 .The population of the last na med is practicallyspeaking all settled along the river Sampean.Sugar-growing, which is economically dependent on high yield of ca ne and high returnsof sugar, is chie fly res tricted to areas fallingunder (5) with naturally rich, volcanic soils; andbecause it in volves so much hand- labour, it accentuates the population figures st ill further.The topography of a district does the same,in the sense, that much leve l ground increasesthe average, whereas a rather hilly regiondecreases it, especia lly where large tractsof this highland country are wooded and reserved in th e interests of irrigation.All the various factors so far discussed combine to produce a striking correlation betweenthe density of th e population and the percentageof the surface of a district, that is under cultivation; a nd , secondarily, how much of this hasbeen made into sawahs, i.e. wet rice fields. Thegraph on p . 259 shows the mutua l relation ofthese two factors in a considerable number ofdistricts . Th e population figures are thosequoted in the Census Returns for 1930. Thepercentages are from the tables given in theAgricultural Atlas published by the Government in 1926. Th e hyp erbolic curves indicatewhat percentage of the total area is occupiedby sawahs. Comparatively low figures aremarked by a square, high figures by a circle.

Th e graph shows that1. In all districts where the population is lessthan 100 per km2, the land under cultivation isDistricts Padi yie ld Populationpieul per balm density

Pandeglang + Tjimanuk 3572 293Menes 2872 136Parungkudjang 2172 66Burniaju 3572 441Madjenang 2372 149

258less than 30% of the total area and the sawahsless than 9%.2. In all districts where th e density of thepopulation is more than 800 the land under cultivation is mor e than 50% of the tot I area andthe sawahs mor e than 40%.3. Between the high figures there appearalso very low ones, a nd , contrariwise, high onesoccur among groups of low ones; this fact is explained by difference in soil types.The comparatively low figures in the righthand upper section indicate that there agricultural ret urns are small. This is due to thefact that the soil is poor (Bantam) or bad (onmarls), or else the irrigat ion is still insufficientlyorganised as in N.W. Batavia, for instance; although the population has done the best it could ,und er the circumstances.The high figures found in the right-hand lowersection show that in those parts irrigation wasgenerally out of the question, as on the islandof Madura. The population was forced, by want,to make use of every square foot of land . Thereare no more forests, nor wood for fuel. Th epeople are partly dependent on salt-making an dother industries for a living. They make whatthey can out of growing maize. Manuring theground is no use as the water supply is theminimum factor.Where we find comparatively high figures inthe left-hand lower section, that means that thedistricts concerned are situated in the lim e areaof the Gunung Sewu. It is difficult to lay o utrice fields there, as it is in Madura, but the lim estone soil is not unferti le. Besides the population can, if need arises, migrate to the rich agricultural lands of the Native States of CentralJava.Where in the upp er portion of the graph, between 20 and 55%, several high figures are foundamong low ones then these apply to districtswhere the soil is fertile, but which include a largeamount of forest reserve, which means that a comparatively small a rea is under cultivation. Areaswhere large tracts of highlands are occupied byEuropean plantations, are also thinly populatedand show densities between 200 and 400.We see, then, that it is possible to trace andpoint ou t the correlation between the density ofthe population in an y given district and (a) thenature of the soil and (b) hydrographic conditions,(c) the res ulting use of th e soil an d (d) theagricultural returns .

To go into the question of these returns indetail would take us too far afield. Suffice it tosay the average yield of padi, when the harvestis successful, ranges between 8Y, and 44 piculsper bahu; a and that, since density of the population depends on the amount of available food,which, again, depends on th e yield of the cultivable land. i.e ., the sawahs, these yie ld, figuresmust correlate with the different densities. Below are fi gu res for a series of adjacent districts:Districts Padi yield Populationpicul pe r bahu den sity

Modjoagung . 44 637Ploso 19 274Ngimbang (Mantup) 14 163Krian (+ Bulang) 3872 703Gunung Kendeng 15 412

~ r9r9. LAND UNDER CULTIVATION:10 " 20 PERCENTAGE OF THE TOTAL S URFA CE~ s so 55Zo as 19,~ ~ 80~ ~ 75 ~ ? It~ 70Z:Jo G5Z~ 60Ii0W 5S\!J~ soZ..

~ ~ 5 WQ,

~ o ;,;0oJ JSWiL~ 30cti l lSw~ 10\!J '1.,.. 8 7ii: IS(t

F,) '00 5X 10

~ ' o : 1 15 20 l:.- Ja JS ~ o 'ts sp 5S 60 GS 70 75 80 esLAND UNDER CULTIVATION: PERCENTAGE OF TH E ' roTAL SURFACE

90 100- FIGURE 72 (see p. 258 ) -


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260MOHR: Soil and population Density

We must be careful, howeve r, in int erpr etingthese figures, as often possibilities for occupancyexert a greater influence on th e density of thepopulation than the differences in th e yieldingpower of the soil.It would be difficult to point out districts inJava where th ere is no v c ~ c influence .at all.Those in the Southern portIOn of the PrIanganResidencies and those North of th e SalatigaModjokerto line approach ~ s t ne':lrly to .thiscondition. In the former, which are tn a tertiarymarl and limestone area, th e density remainsless than 100; in the latter, which include manyteak forests on ridges of calcareous rock andmarl, th e ave rages r ~ n g e between 130 and 300.These figures never rIse t o th e level of those forbett er volcanic ar eas; on th e other hand onlyvolcariic regions where so il has already becomesenile all ove r show figures as low as 300 or less.

basic. Hence th e population figures for thesevolcanic areas may be expected to correspondmore nea rly to those for Bantam tha n to thosefor the rest of Java. In the non-volcanic areasin Sumatra, where poor cl ays tones, ' and still ,poorer quartz sandstones constitute the greaterpart of th e parent ma terial of the soil, the population may be expected to be considerably lessdense. And so it is in fact . Striking examplesof this are to be found both along th e East coasta nd the w.est coast of th e island.In th e former lies Mt. Merap i, which had severa l violent eruptions a century ago and hassince ejected a considerable amount of fairlybasic ash in numero us lesser eruptions. Thesub-section in which the soil profited most bythis action is Oud-Agam (in which Fort de Kockis situated), where the population density in

2. TH E SMALL SUNDA ISLANDS. Baliand Lombok. It would be too soon to apply th estandard for Jav a to these two Islands. Fororganised Europea n Governm ent, which Javahas known for several centuries, was introducedon these islands less than ha lf a century ago.The standard to be a pplied is that of th e Out erProvinces, and accord ing to that Bali and Lombok fall into th e class of the most densely populat ed areas, thanks to th e predominant influenceof young volcanoes a nd exce llent irrigation. Thesub-section of Gianjar has more than 450; thefigures for the ot her south ern sub-sect!ons ran gebetween roughly 190 and 380; according to thea mount of sparsely populated, wooded highlandsor arid limestone tracts th ey include. TheNorthern portion is very mu ch affected by thevery dry East monsoon; owing to the fac t th atfor six months of the year there is no rain, thepopula tion density is only just above 100.We may say that in general during the Eastmonsoon the northern slopes of th e Small SundaIslands suffer from drought without any chanceof irrigation worth mentioning; with the resultthat the population is less dense here than on thesouth ern slopes, even in cases where the soil isderived from exactly the same parent material.The Small Sunda Islands lying directly Eastward of Bali and Lombok are all much lessdensely populated, bu t then for the most partthey have not th e same favourable young volcanic soil or the same irrigation possibilities.

They lack proper lowland tracts. There is nota single volcano in Sumba, Rotti or Timor. Thepopulation density ranges between 73 in Mau mere (Flores), which is very dry but possessesyoung volcanoes, and less than 10 - the minimum _ as in the almost desert wastes of lime-stone country in East Sumba.

1930 was 237, or not counting th e ca pita l, 220 -the highest figure in the whole of Sumatra. TheFort van der Capellen sub-section, to th e SouthEast of Mt. Merapi, also shared the beneficentinfluence of this volcano on th e soil and therethe density is 169. T o the North East is Sulikiwith 92 and Pajakumboh with 48. Beyond thesesub-sections th e influence is no longer di scernibleand we find Bankinang with 18, Kamparkiriwith 2.7 and Siak with 0.9, th e soil getting moreand more exhausted and the inhabitants fewerand fewer, those that are left having settled exclusively along the river banks sur rounded bya n almost uninhabited country.The following table presents two series of sub sections (a) along the coast and (b) just inlandfrom thi s. If the soil were eq ually good or equallybad in all of them they would probably not varygrea tly in population density. As it is th e in-fluence of recent volcanism is plainly apparent.We might enumerate all th e divisions andsub-sections in Sumatra and we should find thatalmost in every case the comparative density orotherwise of th e population could be accountedfor by the nature of the soil, and especially bythe presence or absence of recent volcanic influence . Yet there are exceptions, besides ofcourse such cities as Palembang, which is greatlyaffected by commerce and shipping int erests.There is Kerintji, for instance, which is not sufficiently densely populated for a sub-section witha fin e volcano in it. We may reasonably expectthat its density averag e of 18 will rise in thecourse of time especially since the country hasbeen opened up during th e last decades by meansof new trunk roads. Th e fact that on th e Eastcoast the averages mentioned are less than onth e West coast is accounted for th e preva lencein the former region of European plantationsoccupying large tra cts of tobacco and rubberland, whereas in the latter w e find chiefly native3. SUMATRA's soil is ve ry different fromthat found in Java. There is ha rdly a spot inJav a where young volcanic influence is not present to some degree; the soil in Sumatra is for themost part much older and th e recent vulcanismso common in J ava only occurs here at three orfour poi nts, to be specific - the south ern portionof the Lampongs, the highlands on the borderof Palemb a ng a nd Benkulen, the Pada ng Highlands and the Batak country. Nor is recentvulcanism as it occurs in Sumatra the sa me asth at of J ava; for as a rule more ac id effusiva ca meto the surface here and only very little of the

rice fields .4. In CELEBES conditions are very largelythe sa me as in Sumatra. There too we findyo ung volcanic areas, namely in southwesternCelebes, in th e Mina hasa and also in the Toradjacountry. Th e best of th ese three as far as soilgoes is southwestern Celebes a nd there we consequentl y find the population density risin gabove 100 in several sub -sections, na mely, Pan gkadjene, Goa, T aka lar, Dj eneponto and Bon taeng. It is note worthy, that these are theregions where the East monsoon lasts longest andis dri est. T he South East coast (Bulokomba,Sindj ai and Wadjo) which gets more rain and

'1 picul = ,....., 5/8 quint al. and 1 bahu =,....., 7/ 10 ha .

261

EAST COAST OF SUMATRA..'" " '"u" ~ ] ~ u'" cCoastal " '"


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MOHR: Soil and Population Densityacid rocks ; then limestone with admixtures; thenmarls, which often produce chemica lly rich butphysically unmanageable, heavy clay; a nd finally qua rtz sa ndstone that makes only poorsoi l. .

The more disintegra ted the rock materia l before subjected to chem ica l weathering, the morequickly it is tra nsformed into soil - rich soi l.In this respect there is nothing so good as volca nic ash. Solid and compact rocks weatherslowly.H eavy ra infall at a high temperature not onlywets the soil but leaches it out as well. If thelatter forms slowly, it is leached out th .e momentit is formed and is th erefore poor. It is on lywhere the weathering ta kes place quickly andthe soil is formed rapidly that rich, fertile soil asa temporary phase teven if this last s for severalcenturies) is possible in the trop ics. H ence, onlyon vo lca nic as h, sa nd or tuff. In the course oftime even such so il becomes impoverished byleaching.A dry monsoon retards leaching a nd impoverishment; little rainfall does this even more.Fertility depends then on whether or not it ispossible to irrigate. Where irrigat ion ca n beac hieved, the maximum fertility can be obtained. The fertility is enhanced by plenty ofsunshine and warmth .T he Net herlands Indies demonstrates all thiswith its population figures ranging from 0 tomore than 1600 soul s per km2 Java has thehighest averages, East J ava a nd Ce ntra l J avashowing re latively higher figur es than West Java,which possesses fewer active volcanoes and ahigher rainfall. East Java, Bali, Lo mbok a ndeven S.W . Celebes should be grouped togetheras possessing ma ny cha racte risti cs in common.Sumbawa a nd Flores fall out of line somewhat.We may t herefore per haps expec t that th eseislands will be a ble to deve lop considera bly inth e future, if and when reforestation of th e hillsand irrigation of th e plains have bee n successfully carried out. The Minahasa, too, will beable to support a larger population in the courseof time. The sub-sections of Tobelo and Dj a ilolo

on th e island of Halma heira and also Ternaa ll three possessing young vo lcanic soil and hing a n average population density of 4.4 - 1a nd 31.6 respectively, are too thinly populain view of the nature of their so il. One suspethat this is due to the bad hea lth prevala mong the people. As hygienic conditionsprove, the plains are better drained, andforestat ion proceeds in the highla nds, andforth, this part of th e Moluccas will be ab leoffer a living to a la rger population, thoughmay never become a second Bali.What one vo lcanic eruption can acco mpmay be see n in the Lampongs (S. SumatrBefore 1883 (e ruption of Krakatau !) this wapoor country without much vitality; after tdate it showed remarkable signs of new life bin regard to na tive a nd European agriculture.Agriculturally speaking Madura is. onborderline of overpopul ation. In that islandsa lt industry must be depended on to keeppopulation a live and every yea r migrationsJ ava are necessary, just as the people are forby circumstances to migrate to Burma fromtain parts of British India. The Maduresenot migrate to Borneo, Central-Celebes, Ceror New Guinea, however, for, to put it blunthis \yo uld not pay. It co uld only pa y if onetwo things happened. Either a volcano wohave to sudden ly become active in those regia nd cover the la nd far and wide with a ferlayer of ashes; or the cultura l sta ndard wohave to rise to such a degree that these co un tcame to occ upy the same ag r icu ltura l levelfor instance, the Netherlands, where the poosoil ca n be made ferti le by th e use of mineferti lisers or manure of home or foreign mafact ure, a nd where a ll the best agricul t umethods are applied . But these a re dreams tcould only be rea lised in a far distant fu turperhaps they are not realisable at a ll. Forpresent, th en, a nd for ma ny a long year to co. the fatt rema ins that in the Netherlands Indiespoplllation density is a flt1!ction of the natllYe ofsoil, and this is a fmtction of the presence of acvolcanoes.

the relationship between soil and population density

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