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S. ÖZCAN, H. H. ÖZAYTEKİN

545

Turk J Agric For

35 (2011) 545-562

© TÜBİTAK

doi:10.3906/tar-1102-2

Soil formation overlying volcanic materials at Mount Erenler,

Konya, Turkey

Sıdıka ÖZCAN1, Hasan Hüseyin ÖZAYTEKİN

2,*

1Ümit Özcan Medikal Ltd. Şti., Konya - TURKEY

2Selçuk University, Agriculture Faculty, Department of Soil Science and Plant Nutrition, 42079 Konya - TURKEY

Received: 01.02.2011

Abstract: Studies of soils developed on volcanic materials are insuffi cient in Turkey in light of the wide distribution of

these soils. Th e objectives of the present work were to assess the infl uence of climate and other soil-forming factors on

physical, chemical, and mineralogical characteristics and pedological processes in the soil genesis and soil classifi cation of

4 volcanic soil profi les derived from andesitic parent material, and to determine whether they meet the requirements for

classifi cation as Andisols. Collected from a semiarid climate in Konya, Turkey, these soils are characterized as medium-

and fi ne-textured with low organic matter content, low cation exchange capacity, and low soil moisture retention. Bulk

density was greater than 0.90 g cm–3 in all profi les. In general, phosphate retention was low, and lower than 85% in all

profi les. Th e Al + ½ Fe percentages (by ammonium oxalate) were lower than 2% in all profi les. Th e pH values in NaF

were less than 9.5 in the soils studied. Selective extraction yielded the following relationship in all extractions: Fed >

Feo > Fe

p. Additionally, in most horizons: Al

p > Al

o > Al

d. According to selective dissolution analysis results and index

values, noncrystalline minerals such as allophane, imogolite, and iron-humus complexes have not formed in these soils.

Only noncrystalline minerals were present, such as Al-humus complexes in great quantities, and, in small quantities,

ferrihydrite. Crystallized Fe minerals were more common than other Fe minerals. Feldspar, cristobalite, and quartz were

the most common primer minerals. Hematite, cummingtonite, and magnetite were also found in some profi les. X-ray

diff raction indicated that kaolinite and illite were dominant minerals in the clay fraction; furthermore, a considerable

amount of smectite was found in the clay fraction. Th e local climate, characterized by low precipitation and a long dry

season, obstructs the formation of andic soil properties because of the low rate of weathering and inadequate Si leaching.

As a result, the soils of Mount Erenler were not classifi ed as Andisol but rather as Entisol. Th e major factors determining

soil genesis on Mount Erenler appear to be climate, topography, and the nature of the parent material

Key words: Soil formation, soil classifi cation, volcanic material, Mount Erenler, Konya

Erenler Dağı (Konya, Türkiye) volkanik materyalleri üzerinde toprak oluşumu

Özet: Türkiye’de de volkanik materyal üzerinde oluşan topraklar ile ilgili çalışmalar, dağılımlarıyla karşılaştırıldığında

yetersizdir. Sunulan bu çalışmanın hedefl eri andezitik ana materyal üzerinde oluşan 4 toprak profi linin fi ziksel, kimyasal

ve mineralojik karakteristikleri ile toprak genesisi ve toprak sınıfl andırmasından sorumlu pedolojik prosesler üzerine

iklim ve diğer toprak oluşum faktörlerinin etkisinin araştırılması ve Konya’da yarı kurak iklim şartlarında volkanik

materyal üzerinde oluşan toprakların andisol olarak sınıfl andırılabilmesi için gerekli kriterleri sağlayıp sağlamadığını

belirlemektir. Söz konusu topraklar orta ve ince tekstür, düşük organik madde içeriği, düşük katyon değişim kapasitesi

Research Article

* E-mail: [email protected]

Soil formation overlying volcanic materials at Mount Erenler, Konya, Turkey

546

Introduction

Th e parent materials of Andisols are composed of volcanic ejecta. Soils developed from volcanic materials are characterized by the presence of one or more of the following components: an Al- or Fe-humus complex and short-range-order minerals such as allophane, imogolite, ferrihydrite, and volcanic glass. Th ese soils have developed under a diverse range of climatic conditions and have been studied extensively around the world. Th e majority of studies of volcanic soils in the literature concern soils generated in humid and tropical climates. Many studies have been produced, especially in Japan (Shoji et al. 1982), Argentina (Broquen et al. 2005), Indonesia and New Zealand (Parfi tt and Wilson 1985; Wada 1985; Wada et al. 1986; Van Rast et al. 2008), and Europe (Ezzaim et al. 1999; Sanjurjo et al. 2003; Buurman et al. 2004; Delvaux et al. 2004; Kleber et al. 2004; Barbera et al. 2008; Egli 2008; Sigfusson et al. 2008).

Most studies of volcanic soils are conducted where precipitation is >1000 mm, where andic characteristics have developed in situ and cannot be disputed. Th e formation of Andisols is strongly controlled by climatic factors and its importance is recognized in all suborders, except the Aquands and Vitrands. Th e rate of chemical weathering in the soil notably decreases with decreasing soil moisture and leaching. For example, Torrands formed in arid

climates are the least weathered, and all are regarded to be vitric. Xerands in Mediterranean climates have vitric, melanic, and haplic great groups that indicate the accumulation of large amounts of soil organic matter with a high degree of humifi cation. Shoji et al. (1993) reported that the formation of Xerands was related to climatic conditions characterized by moist winters and dry summers. In comparison with Andisols from humid regions, very little information (Southard and Southard 1989) from Italy (Quantin et al. 1985), Greece (Moustakas and Georgoulias 2005; Drouza et al. 2007), and Turkey (Dingil 2003) is available on the volcanic soils of semiarid climates.

Previous studies clearly indicate that in addition to parent material, climatic conditions are an important factor in weathering since climate determines the weathering product of volcanic materials and therefore the type of noncrystalline minerals that will be formed. Th e fact that noncrystalline mineral formation is the result of oversaturation of the soil solution with Si, Al, and Fe, which control soil solution concentration, makes the infl uence of climate on volcanic soil characteristics easily understood. In the semiarid region of central Anatolia, the weathering products from volcanic materials are quite diff erent from those in humid climates, and soil formation is not yet clearly understood in this environment. More information is needed about soils derived from volcanic parent material in Turkey, as only a few

ve su tutma kapasitesi göstermişlerdir. Elde edilen sonuçlara göre, tüm topraklarda kum ve kaba silt fraksiyonu % 30’dan

yüksek, hacim ağırlığı ise tüm profi llerde 0.90 g cm–3’den yüksek bulunmuştur. Fosfor fi ksasyonu genel olarak tüm

profi llerde düşük bulunmuştur ve % 85’den küçük değerler saptanmıştır. Amonyum oksalatta ekstrakte edilen Al + ½ Fe

yüzdesi bütün profi llerde % 2’den küçük bulunmuştur. NaF deki pH değerleri ise 9.5’in altında tespit edilmiştir. Seçici

ekstraksiyon ile tüm horizonlarda Fed > Fe

o > Fe

p ve çoğu horizonda Al

p > Al

o > Al

d şeklinde bir ilişki saptanmıştır.

Seçici ekstraksiyon analizleri sonuçları ve indeks değerlere göre çalışılan topraklarda allofan, imogolit ve Fe-humus

kompleksleri gibi amorf mineraller saptanmamıştır. Amorf mineral olarak sadece önemli miktarda Al-humus kompleksi

ve çok az miktarda da ferrihidrit bulunmuştur. Kristalize demir mineralleri, diğer demir minerallerinden daha fazladır.

Seçici çözelti analizine ait bazı indeks değerlere göre 3 nolu profi lde eseri miktarda amorf materyalin bulunabileceği

belirlenmiştir. En yaygın primer mineral olarak feldspat (plajiyoklaz), kristobalit ve kuvars saptanmıştır. Bazı profi llerde

hematit, cummingtonit ve magnetit de bulunmuştur. X ışını kırınımları göre kaolinit ve illitin, kil fraksiyonunda

dominant kil minerali olduğu tespit edilmiştir. Ayrıca kil fraksiyonunda önemli miktarda smektit bulunmuştur. Düşük

yağış ve uzun kurak periyot ile karakterize edilen yerel iklim, düşük ayrışma ve yetersiz Si yıkanması nedeni ile andik

toprak özelliklerinin oluşumunu engellemiş ve Erenler dağı üzerinde oluşan topraklar Andisol olarak sınıfl andırılamamış

bunun yerine Entisol olarak sınıfl andırılmışlardır. Erenler Dağı üzerinde toprak genesisini etkileyen temel faktörler,

iklim, topografya ve ana materyalin tabiatı olarak saptanmıştır.

Anahtar sözcükler: Toprak oluşumu, toprak sınıfl andırması, volkanik materyal, Konya, Erenler Dağı


547

studies have been conducted on this subject (Kapur 1980; Özaytekin 2002; Dingil 2003). Th e objectives of this study were to investigate the physical and chemical properties, weathering processes, and pedogenetic products of soils developed from andesite on Mount Erenler in Konya, a semiarid region, and to classify the soils according to the current international classifi cation system. We discuss the extent to which these soils meet the requirements of the true Andisols, as defi ned by soil taxonomy (Soil Survey Staff 2010).

Materials and methods

Site description

Th e study was performed on Mount Erenler in central Anatolia, about 55 km west of the city of Konya, between 37°54ʹ56ʺN and 37°33ʹ22ʺN and between 32°11ʹ06ʺE and 31°51ʹ16ʺE. Th e study area is situated north of the middle Toros Mountains zone. Long-term records show that the mean annual precipitation is 379.38 mm and the total evaporation is 1226.4 mm. According to the Konya meteorological station, the mean annual temperature is 11.5 °C and the mean annual soil temperature at 50 cm is 12.5 °C (DMI 1994). Th e research area has a semiarid Mediterranean climate with low humidity, according to the De Martonne-Bottman rainless index formula (Akman 1990). Soil moisture and temperature regimes are xeric and mesic, respectively, according to the climate data (Soil Survey Staff 1999). Th e study area comprises diff erent stratigraphic and structural formations. Th e oldest formation in the area is the Kızılören formation, which consists of dolomites and dolomitic limestone from the late Triassic-early Jurassic. All of these units were overlaid unconformably by late Miocene-early Pliocene Erenler volcanic materials. Th e volcano was mapped as Kızılören ignimbrite, tuff , andesite, trachyandesite, and Erenkaya ignimbrite, with andesite being the most common formation in the area. Th e volcanic materials in the study area were derived from continental crust and products of old subduction-related volcanism (Kurt et al. 2005).

Sampling and analysis

For the study, 4 representative soil profi les were chosen, and disturbed and undisturbed soil samples were taken from the horizons aft er their

macromorphological identifi cation was completed. Soil samples were dried, gently crushed with a wooden roller, and sieved to 2 mm. Visible roots, stubble, and coarse fragments were removed and stored in plastic bags for use. Soil pH was measured potentiometrically, both in a 1:2.5 soil-water (w/v) suspension and 0.01 N KCl with a glass electrode. Th e pH in NaF was determined in 1 N NaF at a soil-to-solution ratio of 1:50 in a similar way (USDA 2004). Electrical conductivity (EC) was determined potentiometrically in a 1:2.5 soil-to-water suspension (USDA 2004). Particle size distribution was determined by the hydrometer method aft er removal of organic matter using H

2O

2 and stirring in a sodium hexametaphosphate

solution (Bouyoucos 1951). Bulk density (BD) was determined by weighing soil cores aft er drying for 24 h at 105 °C (Blake and Hartge 1986). Water retention at −33 kPa and −1500 kPa was measured in the disturbed soil samples using a pressure plate extractor (Peters 1965). Organic matter in the soils was determined using the Walkley and Black wet digestion method (Van Lagen 1993). Cation exchange capacity (CEC) and exchangeable Ca, Mg, K, and Na were extracted by ammonium acetate (1 N, at pH 7), and quantity was determined by fl ame photometer and atomic absorption spectrophotometer (AAS) (Schollenberger and Simon 1954). Th e amount of carbonate in the soil was measured with a Scheibler calcimeter (USDA 2004). Th e percent base saturation was determined by dividing the sum of the K, Mg, Ca, and Na in mEq 100 g–1 soil to CEC. Phosphate retention capacity was measured according to the methods of the Soil Survey Laboratory Methods Manual (USDA 2004). Selective dissolution of Fe, Al, and Si was conducted by the ammonium oxalate, dithionite-citrate bicarbonate (DCB), and sodium pyrophosphate extraction methods, and their amounts were measured by ASS (USDA 2004). Cations were designated by subscripts o, d, and p for the respective methods. Total element analysis of the soil and rock samples was conducted by fusion with lithium metaborate (LiBO

2) and dilution in a HNO

3-

HF procedure (Chao and Sanzolone 1992), and the contents were measured by inductively coupled argon plasma (ICP). All procedures were replicated 3 times for each soil sample, and means were reported. XRD analysis was also performed on powdered samples as


548

randomly oriented powder mounts with a Shimadzu

XRD-6000 with a Cu anticathode and K fi lter (40 kV,

35 mA). Diff ractometric analysis of the pulverized

saprolite and rock samples was carried out in the

2-40° 2θ range (Jackson 1979). Th e clay fraction (<2

μm) was obtained from the soil aft er destruction of

organic matter with dilute and Na-acetate-buff ered

H2O

2 (pH 5), by dispersion with Calgon and

sedimentation in water. Oriented specimens on glass

slides were analyzed by X-ray diff raction using Cu Kα

radiation from 2° to 15° 2θ with steps of 0.02° 2θ at

2 s step–1. Th e following treatments were performed:

Mg saturation, ethylene glycol solvation (EG), and

K saturation, followed by heating for 2 h at 550 °C.

Minerals and relative abundance were identifi ed by

their diagnostic XRD spacing and evaluated by their

XRD relative peak intensities in the XRD diagram.

IR spectra were recorded over the range of 4000-

400 cm–1 with pellets made with 1 mg of sample and

250 mg of KBr previously heated to 150 °C (White

and Roth 1986). Selected saprolite specimens were

also studied under a scanning electron microscope

(SEM). Th e samples were mounted onto aluminum

stubs and coated fi rst with carbon and then with gold.

Th is double coating proved superior to a coating of

carbon or gold alone. Each specimen was studied at

magnifi cations ranging from 250 to 20,000.

Results

Morphological properties

A description of the study sites and the 4 respective

representative soil profi les are reported in Tables

1 and 2. Th e studied soils were situated on a steep

slope and composed of andesitic materials. Horizon

diff erentiation was poor. Th e solum depth ranged from 20 to 102 cm. Th e studied profi les were well drained. From the profi le description, it is apparent that distinct soil horizons are lacking, with the exception of a weakly defi ned A (in profi les 1 and 2) and cambic B (in profi les 3 and 4). Soil morphology consisted of A horizons of 3-40 cm. Th e cambic B horizon lay under the A horizon in profi les 3 and 4. Soil structure grade is related to clay and organic matter content in soils. Kavdır et al. (2004) reported that soil tensile strength and aggregate stability rose with increasing organic carbon content, while tensile strength of soil aggregates was mostly infl uenced by clay content. In addition, the eff ect of clay content on soil aggregate strength varied with soil organic carbon. In this study, soil structure grade increased with depth in profi le 1, profi le 2, and profi le 3 because of the high clay content of the B layers, but no trend was observed in profi le 4. All had slightly to moderately developed granular A horizons. Profi les 3 and 4 had a moderately to highly developed angular blocky structure in the B horizons. Soil structure was massive in the C layers in all profi les. In general, the upper mineral horizons were characterized by high organic matter content (1.41%-5.95%). Color hue varied from 5YR to 10YR and was characterized by higher values in deeper layers. Th e surface horizons of all profi les showed a brown-to-dark color, with subsurface horizons showing a brown-to-reddish-brown color. A slight reaction with HCl was observed in surface horizons due to the presence of CaCO

3

(Table 3), resulting from the subsurface movement of water from the limestone rich area and atmospheric deposition. Profi les 1, 2, and 4 were characterized by a coarse texture while profi le 3 was characterized by a fi ne texture (Table 4).

Table 1.Selected site characteristics of the studied profi les.

Profile

Coordinates

Parent material Elevation (m) Slope (%) Land useLatitude Longitude

1 32°09ʹ40ʺN 37°49ʹ44ʺE Andesite 1453 25 Grassland

2 32°01ʹ19ʺN 37°47ʹ44ʺE Andesite 1729 15 Forest

3 32°01ʹ15ʺN 37°48ʹ00ʺE Andesite 1740 30 Forest

4 32°02ʹ24ʺN 37°49ʹ52ʺE Andesite 1448 10 Grassland


549

Table 2. Selected morphological characteristics of profi les.

Profi le Horizon Depth (cm)Color

(dry)

Color

(moist)Structurea Field textureb Rootsc Boundary

Biological

activityd

1

A1 0-12 7.5YR3/3 7.5YR3/2 w, me, gr SC 3o gradual, smooth h

A2 12-32 7.5YR4/3 10YR 3/3 mo, me, gr SC 3o abrupt , smooth m

Cr1 31-47 10YR8/3 10YR 8/4 mas SC 2i gradual, irregular n

Cr2 >47 10YR8/3 10YR 8/4 mas SC 1 - n

2

Ah 0-3 7.5YR5/3 10YR3/2 w, f, gr SC 4o clear, smooth m

A 3-15 10YR6/3 10YR3/2 mo, f, gr SC 3o clear, smooth m

AC 15-20 10YR5/3 7.5YR4/3 mo, me, ab SC 2i abrupt, smooth n

Cr >20 10YR8/4 10YR8/3 mas SC 1 - n

3

Ah 0-10 5YR5/3 5YR3/3 w, f, gr C 4k gradual, smooth h

A 10-29 7.5YR4/3 7.5YR3/3 w, me, gr C 4k clear, smooth h

Bw1 29-57 5YR4/3 5YR3/3 st, co, ab C 2i gradual, smooth m

Bw2 57-79 5YR5/3 5YR3/3 st, co, ab C 2i abrupt , smooth w

Cr1 79-116 7.5YR8/3 7.5YR8/3 mas C 2i gradual, smooth w

Cr2 116-179 7.5YR8/2 7.5YR8/2 mas C 1 gradual, smooth n

Cr3 >179 7.5YR8/3 7.5YR8/3 mas C 1 - n

4

A1 0-16 10YR5/4 10YR3/3 w, f, gr SC 3i gradual, smooth m

A2 16-40 10YR6/4 10YR3/2 w, f, gr SC 3i clear, smooth m

Bw1 40-70 10YR6/3 10YR4/4 mas SC 2i clear, smooth w

Bw2 70-102 10YR6/3 10YR4/4 mas SC 2i abrupt , smooth n

Cr1 102-130 7.5YR8/3 7.5YR8/3 mas SC 1 gradual, smooth n

Cr2 >130 7.5YR8/3 7.5YR8/3 mas SC 1 - n

aStructure: w, weak; mo, moderate; st, strong; me, medium; f, fi ne; co, coarse; mas, massive; gr, granular; ab, angular blocky.

bField texture: SC: sandy clay, C: clay.

cRoots: 1, none; 2, few; 3, moderate; 4, common; i, fi ne (<2 mm ); o, medium (2-5 mm); k, coarse (>5 mm).

dBiological activity: n, none; w, weak; m, moderate; h, high.


550

Table 3. Some chemical properties of studied profi les.

Profi le HorizonDepth

(cm)

pH(H2O)

(1:2.5)

pH(KCl)

(1:2.5)

ΔpH

(KCl-H2O)

pH(NaF)

(1:50)

EC

(μS cm–1)

Organic

matter (%)

CaCO3

(%)

1

A1 0-12 6.44 5.81 −0.63 7.62 43.1 2.87 0.3

A2 12-32 6.34 5.75 −0.59 7.66 28.3 2.31 0.6

Cr1 21-47 6.21 5.54 −0.67 7.95 30.9 0.77 -

Cr2 >47 6.70 5.49 −1.21 7.99 22.6 - -

2

Ah 0-3 6.15 5.94 −0.21 8.07 65.4 4.97 0.5

A 3-15 6.13 5.48 −0.65 8.22 37.5 1.93 0.2

AC 15-20 5.99 5.42 −0.57 8.29 32.2 1.43 0.3

Cr >20 6.18 5.38 −0.80 8.09 30.1 0.0 0.0

3

Ah 0-10 6.13 5.97 −0.16 7.70 76.5 5.95 0.3

A 10-29 6.08 5.71 −0.37 7.95 54.9 3.06 0.2

Bw1 29-57 5.90 5.06 −0.84 8.41 28.7 0.44 0.2

Bw2 57-79 5.70 4.80 −0.90 8.80 18.6 0.24 0.2

Cr1 79-116 5.08 4.24 −0.84 8.85 29.6 0.26 0.0

Cr2 116-179 4.17 3.17 −1.00 8.13 416.5 0.0 0.0

Cr3 >179 4.65 2.86 −1.79 7.92 320.0 0.0 0.0

4

A1 0-16 6.19 5.96 −0.23 7.66 68.5 1.41 0.3

A2 16-40 6.28 5.65 −0.63 7.65 20.6 0.81 0.1

Bw1 40-70 6.17 5.84 −0.33 7.75 20.1 0.01 0.2

Bw2 70-102 6.23 5.54 −0.69 7.79 14.2 0.0 0.0

Cr1 102-130 6.35 5.51 −0.84 7.93 24.1 0.0 0.0

Cr2 >130 6.07 5.49 −0.58 7.77 26.0 0.0 0.0

Table 4. Some chemical and physical properties of studied profi les.

Profi le HorizonCEC

(cmolc kg–1)

Base

saturation

(%)

Particle size distribution (%) Exchangeable cations (cmolc kg–1)

Sand Clay Silt Ca Mg Na K

1

A1 12.6 87.6 60.8 22.6 16.6 8.91 1.80 0.08 0.25

A2 13.6 80.0 68.8 20.6 10.6 8.73 1.93 0.10 0.13

Cr1 21.1 78.9 65.0 25.4 9.6 12.09 2.77 1.63 0.16

Cr2 20.8 71.3 70.9 23.4 5.7 10.76 2.35 1.63 0.09

2

Ah 19.4 83.9 48.8 24.6 26.6 12.80 2.81 0.09 0.59

A 16.3 76.8 48.8 32.6 18.6 9.69 2.48 0.08 0.27

AC 22.1 71.0 44.8 36.6 18.6 12.06 3.19 0.17 0.26

Cr 27.6 72.7 52.9 27.4 19.7 14.10 3.96 1.84 0.18

3

Ah 20.1 81.0 35.4 42.9 21.7 12.6 2.48 0.09 1.11

A 17.4 72.4 33.4 48.6 18.0 9.16 2.48 0.08 0.88

Bw1 19.1 65.0 28.4 50.6 21.0 7.97 3.46 0.07 0.91

Bw2 17.7 55.5 34.8 42.6 22.6 5.82 2.81 0.08 1.12

Cr1 23.5 46.1 20.9 55.4 23.7 5.25 3.00 1.65 0.93

Cr2 18.7 33.3 40.9 27.4 31.7 1.83 1.56 2.73 0.11

Cr3 20.1 35.2 24.9 51.5 23.6 2.04 1.70 3.21 0.12

4

A1 11.6 87.9 65.1 21.6 13.3 8.05 1.73 0.06 0.36

A2 14.3 83.3 59.4 23.6 17.0 9.15 2.33 0.07 0.36

Bw1 13.3 80.1 68.4 23.6 8.0 7.88 2.31 0.08 0.38

Bw2 12.6 93.5 69.4 22.6 8.0 8.99 2.58 0.09 0.12

Cr1 23.5 88.1 60.6 29.4 10.0 14.77 4.23 1.62 0.09

Cr2 17.4 81.9 68.7 23.5 7.8 9.95 2.62 1.60 0.08


551

Physical and chemical properties

Some chemical and physical properties of the 4 profi les are shown in Tables 3 and 4. Th e index values of the andic properties of the profi les are also presented in Table 5. All profi les showed a bulk density of >0.9 g cm–3 in the studied soils. BD values of the soils ranged from 1.23 to 2.11 g cm–3, with surface horizons generally having lower BD values than subsurface soils. Th e lower BD values of the surface soils were attributed to the relatively higher organic matter content of the surface soils. All soils followed the general trend of having the highest organic matter content on the surface. Organic matter content ranged from 0.0% to 5.95% and declined rapidly with depth. Soil pH

(H2O) values ranged from 4.17 to 6.70,

with no regular distribution. Soil pH(KCl)

values were consistently less than pH

(H2O) values, and ΔpH (pH

(KCl)

− pH

(H2O)) values ranged between −0.16 (profi le 3)

and −1.79 (profi le 3), indicating a net negative charge of the soils. Th e pH in NaF values ranged from 7.62 to 8.85, with values lower than 9.5 in all soils, indicating a lack of Al activity. CEC values ranged from 11.6 to

27.6 cmolc kg–1 and showed no trend with depth. CEC

values were correlated with clay fraction content (r

= 0.405, P < 0.10). Exchangeable bases were present generally in order of abundance, with Ca > Mg > K > Na in surface horizons and Ca > Mg > Na > K in subsurface horizons. Exchangeable Ca, Mg, Na, and K ranged from 1.8 to 14.77 cmol

c kg–1, 1.56 to 4.23

cmolc kg–1, 0.06 to 3.21 cmol

c kg–1, and 0.08 to 1.12

cmolc kg–1, respectively. Base saturation values ranged

between 33.3% and 93.5% with high values, except in the C layers of profi le 3. Th e texture of the soils was sandy clay loam and clayey (profi le 3). Sand content ranged from 20.9% to 70.9%, silt content from 5.7% to 31.7%, and clay from 20.6% to 55.4%. With the exception of profi le 3, all profi les had high sand content, but clay concentrations generally increased with depth. Th e CaCO

3 content was close

to detection limits and ranged from to 0% to 0.6%. Phosphate retention ranged from 6.3% to 42.7% and was <85% in all horizons. It was higher than 25% only in the deeper horizons of profi le 3. Water retention at −1500 kPa and −33 kPa ranged from 5.3% to 31.3% and 12.5% to 49.4%, respectively. Th e

Table 5. Index values of the andic properties of studied soils.

Profi le Horizon Depth

Phosphorous

retention

(%)

Alo + ½ Fe

o

(%)

Bulk density

(g cm–3)

Water retention (% w/w)2-0.02 mm (%)

−33 kPa −1500 kPa

1

A1 0-12 6.3 0.173 1.49 14.8 7.2 72.0

A2 12-32 7.8 0.182 1.44 13.9 7.7 76.4

Cr1 21-47 9.9 0.213 2.01 16.3 9.1 69.2

Cr2 >47 9.5 0.152 1.86 15.1 8.4 75.7

2

Ah 0-3 17.2 0.286 1.37 26.4 12.4 72.1

A 3-15 20.7 0.358 1.37 20.4 9.5 62.5

AC 15-20 26.1 0.342 1.28 29.6 14.3 59.9

Cr >20 23.8 0.203 1.80 31.7 19.3 70.8

3

Ah 0-10 21.2 0.479 1.36 33.3 18.8 40.8

A 10-29 28.8 0.653 1.40 26.9 16.6 37.3

Bw1 29-57 40.3 0.796 1.43 28.1 18.4 33.8

Bw2 57-79 39.0 0.733 1.23 32.3 21.6 43.3

Cr1 79-116 42.7 0.451 1.47 47.3 31.3 27.3

Cr2 116-179 34.3 0.326 1.31 49.4 27.0 57.1

Cr3 >179 34.1 0.347 1.53 41.2 19.7 32.4

4

A1 0-16 11.3 0.245 1.53 13.1 6.3 75.4

A2 16-40 14.8 0.175 1.59 15.6 6.4 67.9

Bw1 40-70 16.1 0.136 1.50 12.8 6.5 73.8

Bw2 70-102 15.4 0.173 1.55 12.5 6.2 74.5

Cr1 102-130 14.2 0.182 1.82 23.2 9.5 66.9

Cr2 >130 16.3 0.213 2.11 14.2 5.3 75.3


552

lower water retention capacity of the samples could have been caused by lower amorphous materials content. Th e results of selective dissolution analysis are given in Table 6. Si

o content was less than 0.2% in

all horizons, ranging from 0.0379% to 0.1737%. Sio

values increased with depth in profi le 1, but no trend was observed in the other profi les. Al

o and Fe

o values

ranged from 0.0891% to 0.4776% and from 0.050% to 0.636%, respectively. Th e highest Al

o and Fe

o values

were observed in the deeper horizons of profi le 3. Fe

p and Al

p values ranged from 0.0010% to 0.104%

and from 0.08154% to 1.4664%, respectively. DCB aff ected crystallized materials more than the other extracts. In the studied profi les, Fe

d ranged from

0.420% to 1.973%, and Ald ranged from 0.0757%

to 0.2387%. Fed decreased with depth, whereas Al

d

showed no trend with depth.

Mineralogical properties

X-ray diff ractograms of selected samples are shown in Figures 1 and 2. No distinct diff erences in clay mineral distribution with depth were observed, and pedons from all geomorphic surfaces had similar mineral components. In the clay fraction, 3 intense peaks with weak and masked signals were observed.

Th e Mg-saturated clay exhibited 3 intense peaks at

1.4-1.5 nm, 1.0 nm, and 0.72-0.73 nm. Th e refl ection

at 0.72 nm disappeared at 550 °C. Glycolation

expanded part of the peak, with a shoulder at about

1.6-1.7 nm, and the same peak closed to 1.2-1.4 nm

aft er K saturation at 20 °C. At 550 °C, however, an

ill-defi ned diff raction band between 1.0 and 1.1 nm

was observed, indicating the presence of smectite

with illite and kaolinite. X-ray diff raction (XRD)

patterns of powdered samples indicated the presence

of cristobalite, feldspars, and quartz. Th e feldspars

were mostly plagioclases. In addition, soils contained

minor amounts of hematite, cummingtonite, and

magnetite. IR spectra were taken from some horizons

to identify the mineralogical composition of the

studied soils. Th e IR spectra of the clay samples are

given in Figure 3. Th e IR spectra of the soil showed

6 principal peaks at 779-791, 1032-1034, 1614-1638,

2360-2363, 3623-3627, and 3699-3702 cm–1. In

the IR spectra, OH peaks of H were observed as a

structurally large band at 3100-3500 cm–1. Th e bent

vibration peaks belonging to H were found at 1636

cm–1, and a Si-C single vibration band was present at

790 cm–1.

Table 6. Selective dissolution analyses of <2 mm of soils of studied soils (%).

Profi le Horizon Fed

Feo

Fep

Ald

Alo

Alp

Sio

1

A1 1.227 0.167 0.039 0.149 0.089 0.838 0.050

A2 1.074 0.089 0.061 0.103 0.137 0.875 0.052

Cr1 1.198 0.077 0.031 0.155 0.174 0.839 0.051

Cr2 1.213 0.050 0.032 0.150 0.127 0.931 0.061

2

Ah 1.406 0.165 0.040 0.164 0.204 1.221 0.102

A 1.664 0.214 0.039 0.206 0.251 1.036 0.066

AC 1.140 0.157 0.032 0.157 0.263 1.466 0.077

Cr 1.422 0.084 0.020 0.158 0.161 1.159 0.096

3

Ah 1.689 0.449 0.089 0.171 0.254 0.859 0.098

A 1.973 0.599 0.105 0.239 0.353 0.900 0.114

Bw1 1.964 0.636 0.063 0.224 0.478 0.939 0.174

Bw2 1.739 0.530 0.071 0.168 0.468 1.026 0.089

Crt1 1.378 0.194 0.001 0.154 0.354 0.821 0.064

Crt2 1.352 0.123 0.059 0.115 0.264 0.923 0.064

Crt3 1.399 0.191 0.003 0.195 0.251 0.815 0.065

4

A1 1.053 0.091 0.038 0.076 0.168 0.842 0.046

A2 1.275 0.127 0.041 0.119 0.126 1.018 0.056

Bw1 1.162 0.128 0.051 0.102 0.118 0.900 0.058

Bw2 0.983 0.178 0.021 0.137 0.156 0.890 0.038

Cr1 0.420 0.101 0.036 0.089 0.124 0.912 0.046

Cr2 0.661 0.051 0.030 0.121 0.111 1.026 0.050


553

Mg+2

Mg +EG+2

K+

untreated

K++ 550 Co

0 .9 9

1.400.71

2 4 6 8 10 12

2 Cu Kθ α

a

Mg+

Mg++EG

K+ 550 oC

b

2 4 6 8 10 12

1.420.99 0.73

2 Cu Kθ α

K++ 550 Co

K+

untreated

Mg +EG+2

Mg+2

2 4 6 8 10 12

c

1.45

1.06 0.72

2 Cu Kθ α

K++ 550 Co

K+

untreated

Mg +EG+2

Mg+2

2 4 6 8 10 12

d

1.49

1.06 0.74

2 Cu Kθ α

K+

untreated

Figure 1. X-ray diff ractograms of selected samples: a) P1-A1; b) P2-Ah; c) P3-Ah1; d) P4-A1; d-values in nm.


554

Profile 1 A1 Profile 2 Ah

Profile 3 Ah Profile 4 A2

5 10 15 20 25 30 35 40 5 10 20 25 30 35 40

5 10 20 25 30 35 405 10 20 25 30 35 40

15

1515

[ 2 ]o θ [ 2 ]o θ

[ 2 ]o θ[ 2 ]o θ

Cr

0.418

F0.404

F0.320

F0.376

Q

0.335

F0.402

Cr

0.407

F 0.230

4 F

0.37

Q

0.332 Cu0.297

H0.269

Cr0.403

Q0,333

F 0,317

M0.251

Cr0.408

F0.403

Q0.333

F0.375

F 0.371

H0.269

Figure 2. X-ray diff ractograms of whole soils of representative horizons; F: feldspar; Q: quartz; H: hematite; Cr:

cristobalite; Cu: cummingtonite; M: magnetite; d-values in nm.


555

Geochemical properties

Concentrations of the measured elemental oxides

are shown in Table 7. All soils contained much SiO2,

Al2O

3, and Fe

2O

3 with minor TiO

2, MnO

2, and

P2O

5. Th e SiO

2 concentration rose to 68.09%. Al

2O

3

values ranged from 15.02% to 27.84% and tended

to increase with depth. Th e highest Fe2O

3 value

was observed in profi le 3 as 9.92%. CaO values

were higher in the surface than the subsoil. MgO

values ranged from 0.52% to 0.98% and showed

no important diff erences among the horizons. Th e

small amount of MgO was due to the lack of biotite.

Al concentration correlated with clay distribution in

the soils (r = 0.724, P < 0.01). In the studied soils,

Al2O

3 values were similar in solum and parent

material as a result of the low weathering rate. K2O

and Na2O values ranged from 0.65% to 3.03% and

from 0.18% to 3.28%, respectively. K2O and Na

2O

values correlated with the presence of feldspar, the

most common mineral in andesitic rock.

Discussion

Physical and chemical properties

Nanzyo et al. (1993) explained that fresh ashes

have a bulk density greater than 1.5 g cm–3, and

this value decreases with weathering and the

development of soil porous structure thanks to the

presence of noncrystalline materials and organic

matter. All of the horizons of the studied profi les

showed a bulk density greater than 0.9 g cm–3, which

is characteristic of Andisols. Bulk density is generally

high because of high sand content, low weathering

rates, and lack of smaller particle densities like

allophane and imogolite, factors considered

responsible for lower bulk density (Wada 1989). Th e

high (<2) values of bulk density were determined in

the Cr horizons in profi les 1 and 4. Despite being the

parent material, this horizon is relatively soft when

wet. For this reason, it is designated as Cr with a

higher bulk density. Organic matter concentrations

were higher in the surface horizons and decreased

3627

3624

4000

(1)

(2)

(3)

(7)

(6)(4)

(5)

2000 1000 cm-13000

4000 2000 1000 cm-13000 4000 2000 1000 cm-13000

4000 2000 1000 cm-13000

3701 3471 2360

2360

1616

1033

1011161436233702

3623

3624

3699

2363

1638

1629

2360

1032

1034

36253699

3625

1636

1638

10321034

1634

1032

790

791

779541

781

2362

2360

793

792

2361

Figure 3. Infrared spectra of clay samples. 1 and 2: IR spectra from profi le 1 (A1 and Cr1, respectively); 3: from profi le 2 (A); 4

and 5: from profi le 3 (A and Bw1, respectively); 6 and 7: from profi le 4 (A1 and Bw2, respectively).


556

with depth in all profi les. Organic matter content

was relatively high compared with the arid regions

of Turkey, but compared with other Andisols in

the world, the organic matter content was very low.

Low precipitation and a long dry season limited the

organic matter level. Th e reasons for lower organic

matter content include the lower clay content of the

horizons and the lack of metal-humus complexes,

indicating a lower content of Alp and Fe

p. Most soils

were weakly acidic, but some were moderately to

strongly acidic (profi le 3). Th e higher pH(H2O)

values

might be related to lower Al activity and lower

organic matter content. Th e pH values (in most cases

above 6.0) were relatively high considering the nature

of the parent material and the absence of carbonates.

Th e pH in NaF solution has been proposed as a rapid

test for allophane; here, pH(NaF)

ranged from 7.62 to

8.85. Th e lower pH(NaF)

values are in agreement with

the very low amounts of oxalate-extractable Si (Sio)

in the soils, further confi rming their nonallophanic

nature. Values of pH(NaF)

greater than or equal to

9.5 point to the dominance of the noncrystalline

minerals indicative of soils characterized by andic

properties. In some horizons, the CEC values were

greater than 20 in spite of low organic matter and

clay content. Th is refl ects the existence of high charge

density aluminosilicates (smectite), as illustrated in

Figure 1. Smectite was identifi ed by the presence of a

1.4-nm refl ection with Mg saturation that expanded

to 1.6-1.7 nm under glycol treatment. Exchangeable

bases were present generally in order of abundance,

with Ca > Mg > K > Na in surface horizons and

Ca > Mg > Na > K in subsurface horizons. Th is

trend diff ered in profi le 3, with Na being the most

abundant cation in the Cr2 and Cr3 horizons. Th is

indicates that the feldspars were plagioclases, which

Table 7. Th e results of total element analysis of studied profi les (%).

Profile Horizon Depth SiO2

Al2O

3Fe

2O

3MgO CaO Na

2O K

2O TiO

2P

2O

5MnO

1

A1 0-12 68.09 15.02 3.48 0.57 2.23 2.64 3.63 0.45 0.13 0.07

A2 12-32 65.58 15.49 4.76 0.83 1.81 2.12 3.33 0.62 0.22 0.09

Cr1 21-47 65.62 16.67 4.43 0.85 2.39 2.50 3.10 0.50 0.15 0.05

Cr2 >47 66.92 15.80 4.26 0.85 2.40 2.68 3.34 0.50 0.15 0.05

2

Ah 0-3 55.95 18.62 7.19 0.89 2.19 2.00 2.63 1.01 0.23 0.11

A 3-15 57.02 19.51 7.73 0.89 2.12 2.03 2.61 1.08 0.20 0.12

AC 15-20 56.21 21.10 7.34 0.86 1.64 1.63 2.37 0.98 0.18 0.10

Cr >20 57.11 21.34 6.65 0.75 1.64 1.72 2.56 0.93 0.22 0.10

3

Ah 0-10 54.28 17.70 9.79 0.86 1.03 0.87 1.99 1.38 0.15 0.25

A 10-29 54.88 19.63 9.92 0.98 0.98 0.95 2.09 1.32 0.13 0.18

Bw1 29-57 53.86 21.94 9.06 0.97 0.78 0.79 1.87 1.17 0.13 0.10

Bw2 57-79 52.47 23.65 9.27 0.86 0.52 0.52 1.32 1.17 0.12 0.12

Cr1 79-116 50.49 27.84 7.61 0.63 0.18 0.18 0.65 1.00 0.13 0.10

Cr2 116-179 52.07 26.11 8.19 0.54 0.11 0.29 0.81 1.07 0.12 0.09

Cr3 >179 54.12 24.00 8.34 0.56 0.13 0.47 1.42 1.13 0.07 0.09

4

A1 0-16 67.18 15.40 3.44 0.52 2.61 2.68 3.22 0.47 0.16 0.08

A2 16-40 67.03 15.82 4.10 0.60 2.37 2.52 3.25 0.54 0.19 0.09

Bw1 40-70 67.74 15.84 3.89 0.56 2.34 2.57 3.27 0.47 0.11 0.08

Bw2 70-102 67.27 16.13 4.21 0.60 2.29 2.58 3.22 0.49 0.12 0.08

Cr1 102-130 65.73 16.97 4.34 0.73 2.36 2.60 3.02 0.49 0.10 0.09

Cr2 >130 66.45 16.85 3.54 0.63 3.31 3.28 2.86 0.43 0.14 0.07


557

means that the parent materials were rich in Na and

Ca. Exchangeable cation content increased with

depth, but this attributed vegetation nutrient cycling

is limited. Base saturation values changed in relation

to pH and were higher than 50%, except in the C

layers of profi le 3. High base saturation indicates that

precipitation is inadequate for the leaching of bases.

Soil texture is generally described as sand, except in

profi le 3, indicating a low rate of weathering. Under

climatic conditions of low precipitation and long

dry seasons, the weathering process is not easily

facilitated. Elevated concentrations of clay, especially

in the B horizons, are the result of the transformation

of primary minerals to clay minerals (Beckmann et

al. 1974). Th e high rate of change in clay content in

the deeper soil may be due partly to the fact that clays

can be formed from percolating solutions. Th e high

sand content of the profi les and the sandy clay loam

textures indicate a low weathering rate; however,

increased clay content in the cambic and C horizons

of profi le 3 showed that clays that are neoformation

minerals could be inherited from the parent material.

Th ese clay minerals are formed by the alteration of

feldspars to clay minerals. Th e XRD results confi rmed

the presence of clays in these horizons. Th e obtained

kaolinite peaks in the power x-ray diff ractograms

verify the inheritance of this mineral from the parent

material. All samples showed very low P retention,

confi rming that active forms of Al and Fe have not

accumulated in the soils. Th is capacity can be linked

to the pH measured in NaF. Phosphate retention

depends on the pH in water, and the low pH-in-NaF

values confi rm the low P retention of the studied soils.

Nevertheless, relatively high P retention in the Bw1

and Bw2 horizons of profi le 3 was attributed to the

presence of Fe oxides (Gunjigake and Wada 1981).

Water retention at −1500 kPa and −33 kPa in these soils

is very low compared with expectations for Andisols

worldwide, with the exception of profi le 3. Andisols

have the capacity to retain large quantities of water

as a result of meso- and micropores developed as a

result of this situation, and there is a typical spherical

and hollow structure to allophane and allophane-like

minerals retaining water at high suction (Shoji et al.

1993). Th e high water retention in some horizons is

due to the presence of other clay mineral content in

the place of allophane and imogolite.

Al, Fe, and Si values determined by selective

dissolution analysis and index values of selective

dissolution analysis provide very important knowledge

of the mineralogical composition of volcanic soils.

According to Wada (1989), acid oxalate extracts

the following: 1) aluminum (Alo) from allophane,

imogolite, allophane-like minerals, and Al-humus

complexes; 2) iron (Feo) from ferrihydrite and Fe-

humus complexes; and 3) silica (Sio) from allophane

and imogolite. Meanwhile, sodium dithionite citrate

(DCB) extracts: 1) aluminum (Ald) from allophane,

Al-humus complexes, and noncrystalline oxides; and

2) iron (Fed) from ferrihydrite, crystalline oxides, and

Fe-humus complexes. Na4S

2O

7 extracts aluminum

(Alp) and iron (Fe

p) from organic complexes. Some

index values from selective dissolution analysis are

given in Table 8. Th e rather low Sio, Al

o, and Fe

o

values highlighted trace amounts or an absence of

noncrystalline materials in the studied soils. Th e

very small amount of Feo also indicates that Fe

oxides are mainly crystallized. Th e overall low pH(NaF)

values of the soils can be indicative of nonallophanic

materials. Low pH(NaF)

values are in agreement with

very low amounts of oxalate-extractable Si (Sio).

Pyrophosphate-extractable Al (Alp) and Fe (Fe

d)

provide the data for organometallic complex forms

of Fe and Al. Alp and Fe

p are very high in Andisols,

but in the studied soils, these values were very low

compared with those of other Andisols because of the

very low organic matter content of the studied soils.

Concentrations of Feo were consistently higher than

concentrations of Fep. A low Fe

p-to-Fe

o ratio (<0.9

in all horizons) indicates that Fe-humus complexes

are limited. A ratio of <0.42 in profi le 3 suggests that

the non- or poorly crystalline form of Fe is mainly

ferrihydrite. Fed values were higher than the other

fractions in the studied soils. Alo was higher than Al

d

in general, but in profi les 1 and 4, Ald was higher than

Alo in some horizons. Fe

p/Fe

d values were quite small,

as were Feo/Fe

d values, probably because crystalline

Fe oxides were more abundant than ferrihydrite,


558

and Al was present as Al-humus complexes. Th e rate

of Alp/Al

o was used to measure a characteristic of

Andisols whereby an Alp-to-Al

o ratio lower than 0.1

confi rms the absolute presence of allophane. Alp/Al

o

values were higher than 0.1 in all profi les, indicating

a lack of allophane and the existence of Al-humus

complexes, as explained previously (Prado et al 2007).

Th e ratio of (Alo – Al

p) to Si

o can be used to estimate

allophane and imogolite formation in Andisols.

Th is rate ranges from 1 to 2.5 in most Andisols; it

is close to 1 in allophane-rich Andisols and close

to 2 in imogolite-rich Andisols. Th e ratio of (Alo

–

Alp) to Si

o was outside the limits demonstrating the

lack of allophane and imogolite in the studied soils

and was negative in all profi les. In the studied soils,

low precipitation and a long dry season restricted

the leaching of silica. Allophane formation was

obstructed by the inadequate release of Al due to a

low weathering rate, use of released Al by secondary

clay minerals, and inadequate desilication. Th e

extremely small amounts of Alo and Si

o compared

with Fed suggest that crystalline aluminosilicates

with high charge density could be occurring through

neoformation, consuming both the Al and Fe released

from the weathered parent material. Consequently,

all selective dissolution analysis results and index

values of selective dissolution analysis indicate

that noncrystalline minerals such as allophane and

imogolite have not formed in these soils. Parfi tt and

Kimple (1989) reported that allophanes are rarely

found in soils under ustic, xeric, or aridic moisture

regimes due to the restricted leaching of silica.

Table 8. Index values of selective dissolution analysis of the studied soils.

Pro

file

Ho

rizo

n (Fed – Fe

o)

×

100/Fed

Feo/Fe

dFe

d/Fe

tFe

p /Fe

oFe

p /Fe

d(Al

o – Al

p)/Si

oAl

p/Al

dAl

o/Al

dAl

p/Al

o

1

A1 86.4 0.136 0.503 0.23 0.03 −15.0 5.64 0.60 9.4

A2 91.7 0.083 0.321 0.69 0.06 −14.2 8.53 1.34 6.4

Cr1 93.6 0.064 0.386 0.40 0.03 −13.1 5.43 1.13 4.8

Cr2 95.9 0.041 0.406 0.64 0.03 −13.2 6.21 0.85 7.3

2

Ah 88.3 0.117 0.280 0.24 0.03 −10.0 7.43 1.24 6.0

A 87.1 0.129 0.307 0.18 0.02 −11.8 5.04 1.22 4.1

AC 86.2 0.138 0.221 0.20 0.03 −15.6 9.32 1.67 5.6

Cr 94.1 0.059 0.305 0.24 0.01 −10.4 7.33 1.02 7.2

3

Ah 73.4 0.266 0.246 0.20 0.05 −6.2 5.04 1.49 3.4

A 69.6 0.304 0.283 0.17 0.05 −4.8 3.77 1.48 2.5

Bw1 67.6 0.324 0.309 0.10 0.03 −2.7 4.20 2.14 2.0

Bw2 69.5 0.305 0.268 0.13 0.04 −6.2 6.12 2.79 2.2

Cr1 85.9 0.141 0.258 0.01 0.00 −7.3 5.33 2.30 2.3

Cr2 90.9 0.091 0.236 0.48 0.04 −10.3 8.05 2.31 3.5

Cr3 86.3 0.137 0.239 0.01 0.00 −8.7 4.18 1.29 3.2

4

A1 91.4 0.086 0.436 0.41 0.04 −14.7 11.13 2.21 5.0

A2 90.0 0.100 0.444 0.32 0.03 −16.0 8.56 1.06 8.1

Bw1 89.0 0.110 0.424 0.40 0.04 −13.4 8.81 1.15 7.6

Bw2 81.9 0.181 0.333 0.12 0.02 −19.3 6.50 1.14 5.7

Cr1 76.0 0.240 0.136 0.36 0.09 −17.1 10.20 1.39 7.3

Cr2 92.3 0.077 0.266 0.58 0.04 −18.5 8.47 0.75 9.3


559

A similar result was reported by Moustakas and

Georgoulias (2005), who found trace amounts of

allophane on the island of Th era (Greece) under a

xeric moisture regime.

Mineralogical properties

Th e X-ray diff ractograms showed only weak and

oft en not very clear signals in the region of 2-15° 2θ.

Results of the X-ray analysis are shown in Figures

1 and 2. As illustrated in Figure 1, a wide range

of phyllosilicates occurs, including 1:1 minerals

(kaolinite) and various 2:1 minerals. Smectite is rare,

occurring only in trace amounts. In our samples,

peaks are mostly weak and poorly crystallized.

In the studied soils, diff erences in composition

between topsoil and subsoils are generally small.

Illite is the dominant constituent of profi le 1 and

occurs in greater amounts higher in the surface.

Kaolinite and smectite follow illite. XRD results for

profi les 2 and 4 revealed the following relationship:

kaolinite > illite > smectite. A similar distribution

of clay minerals was observed in the Bw1 and Cr1

horizons of profi le 3, but in the Ah horizon this trend

changed to illite > kaolinite > smectite. Plagioclase,

quartz, and cristobalite were the dominant primer

minerals. Hematite was found in small amounts of

sesquioxide in all profi les and is a common minor

constituent of volcanic ash, especially from volcanoes

that are very hot when erupting, leading to oxidation

of iron compounds at high temperatures to produce

hematite. Th e presence of hematite explains why

these soils appear red, particularly during the dry

season. Th e presence of crystalline Fe oxides is in

agreement with the low Feo-to-Fe

d ratios, indicating

that a considerable amount of Fe is released from the

weathering of Fe-bearing minerals and transformed

to crystalline Fe oxides. Th e Feo-to-Fe

d ratio is related

to the degree of crystallization of the Fe oxides, and it

has been found that a low ratio indicates a weak degree

of soil development (Schwertmann 1985; Vacca et

al. 2003). Concentrations of Feo are consistently

higher than Fep, indicated by Fe

p-to-Fe

o ratios of

<0.42 in most horizons, suggesting that the non- or

poorly crystalline form of Fe is mainly ferrihydrite.

Magnetite (Fe3O

4) was also found in some horizons.

Consequently, the relatively lower degree of leaching

in this semiarid climate with alternating dry and

wet seasons is believed to cause higher Si contents

in soil solution and to limit allophane and imogolite

formation. Th e small diff erences in clay mineral type

and amount, similar content of primary minerals,

high sand content in the profi les, and the existence

of an A-C or A-Bw-C horizon arrangement indicate

small pedogenetic diff erences. Allophanes have 4

major IR absorption regions. No peaks were found in

these regions in the studied soils, but 2 principal peaks

appearing at 790 and 1636 cm–1 are characteristic of

diff erent forms of silicon dioxide and indicate the

existence of amorphous silica. Th e maxima in the

1630-1650 cm–1 and 600-800 cm–1 regions are typical

of metal-organo complexes and phyllosilicates,

respectively. Th e results of the infrared spectra of

the clay samples of the studied soils did not show

the usual features for allophane and imogolite in the

spectrum, thereby indicating an absence of allophane

and imogolite. Th ese fi ndings are in agreement with

the SEM images taken to confi rm the presence of

allophane and imogolite (Figure 4).

Classifi cation

Th e andic properties analyzed in the fi ne soil

fraction (<2 mm) were determined following

standards used to classify soil by the Soil Survey

Staff (2010). From Table 5, it can be seen that the

studied soils do not meet all the requirements. As a

result, the soils developed at Mount Erenler cannot

be classifi ed as Andisols. According to soil taxonomy,

profi les 1 and 2 are classifi ed as Entisols because they

have no diagnostic surface or subsoil horizons except

for ochric epipedon; therefore, they are classifi ed

as Orthent because they have no other suborder

properties of Entisols. Volcanic glass was not

determined in this study. Because Kurt et al. (2005)

reported that parent material contains <3% volcanic

glass, this value does not satisfy the requirements of

vitric or andic subgroups for other orders. Th erefore,

profi les 1 and 2 are Xerorthents in the great group

of Entisols because of a xeric moisture regime, and

the soils are in the subgroup of the Lithic Xerorthents

because they have lithic contact within 50 cm. Profi les


560

a b

c d

e f

g h

Figure 4. SEM photograph of selected samples. a) Image from profi le 1-A2 with a fresh-broken surface; clusters are roughly spheroidal

with laminar-skeletal fabric and face-face and face-edge unions between particles. b) Area from (a) enlarged. c) Image from

profi le 2-A with skeletal fabric, mainly composed of silt- and clay-sized particles. d) Area from (c) enlarged. e) Image from

profi le 3-Bw1, with colloidal particles covering and giving rise to face-face unions between silt-sized particles, between 5 and

10 μm. f) Area from (e) enlarged. g) Image from profi le 4-A2 with a fi eld of clay particles (domains) with face-face unions and

silt particles. h) Area from (g) enlarged.


561

3 and 4 are classifi ed as Inceptisols because they

have a mollic and cambic horizon within 10 cm of

the mineral soil surface; they are classifi ed as Humic

Haploxerept because they have a xeric moisture

regime and mollic epipedon and have no properties

of the suborder Xerept.

In conclusion, we tested the hypothesis that climate

has a greater eff ect than other soil-forming factors

on formation of Andisols by 4 profi les developed on

volcanic materials. Noncrystalline minerals such as

allophane and imogolite were not formed in these

soils because of a low rate of weathering, inadequate

Si leaching as a result of low precipitation, and a long

dry season. Th e local climate has a dry season, and

the very small amount of precipitation negatively

aff ected soil moisture. Th e soils of Mount Erenler did

not show andic properties and were not classifi ed as

Andisol but rather as Entisol.

Acknowledgments

Th is study is a part of a master’s thesis produced by Sıdıka Alp and was supported by TÜBITAK (Scientifi c and Technological Research Council of Turkey, Project No: TOVAG 108O302) and the Selçuk University BAP Offi ce (Coordinating Offi ce of Scientifi c Research Projects, Project No: 08201020).

References

Akman Y (1990) Climate and Bioclimate. Palme, Ankara (in Turkish)

Barbera V, Raimondi S, Egli M, Plötze M (2008) Th e infl uence of

weathering processes on labile and stable organic matter in

Mediterranean volcanic soils. Geoderma 143: 191-205.

Beckman GG, Th ompson CH, Hubble GD (1974) Genesis of red

and black soil in basalt on the Darling Downs, Queensland,

Australia. J Soil Sci 25: 265-281.

Blake GR, Hartge KH (1986) Bulk density. In: Methods of Soil

Analysis, Part 1. Physical and Mineralogical Methods,

Agronomy Monograph No. 9 (Ed. A Klute). SSSA, Madison,

WI, USA, pp. 363-375.

Bouyoucos GJ (1951) A recalibration of the hydrometer method for

making mechanical analysis of soils. Agron J 43: 434-438.

Broquen P, Labartini JC, Candan F, Falbo G (2005) Allophane,

aluminum, and organic matter accumulation across a

bioclimatic sequence of volcanic ash soils of Argentina.

Geoderma 129: 167-177.

Buurman P, Rodeja EG, Cortizas AM, van Doesburg JDJ (2004)

Stratifi cation of parent material in European volcanic and

related soils studied by laser-diff raction grain-sizing and

chemical analysis. Catena 56: 127-144.

Chao TT, Sanzolone RF (1992) Decomposition techniques. Journal

of Geochemical Exploration 44: 65-106.

Delvaux B, Strebl F, Maes E, Herbillon AJ, Brahy V, Gerzabek M

(2004) An andosol- cambisol toposequence on granite in the

Austrian Bohemian Massif. Catena 56: 31-43.

Dingil M (2003) Türkiye’de Andisol Ordosuna Girebilecek Bazı

Toprakların Özellikleri, Genesisi ve Sınıfl andırılması. Doktora

Tezi. Çukurova Üniversitesi, Fen Bilimleri Enstitüsü, p. 129.

DMI (1994) Meteorology Bulletin. Prime Ministry Printing

Establishment, Ankara.

Drouza S, Georgoulias FA, Moustakas NK (2007) Investigation of

soils developed on volcanic materials in Nisyros Island, Greece.

Catena 70: 340-349.

Egli M, Mirabella A, Nater M, Alioth L, Raimondi S (2008) Clay

minerals, oxyhydroxide formation, element leaching and

humus development in volcanic soils. Geoderma 143: 101-114.

Ezzaim A, Turpault MP, Ranger J (1999) Quantifi cation of weathering

processes in an acid brown soil developed tuff (Beaujolais,

France). Part 1. Formation of weathered rind. Geoderma 87:

137-154.

Gunjigake N, Wada K, (1981) Eff ects of phosphorous concentration

and ph on phosphate retention by active aluminium and iron

of Ando soils. Soil Science 132: 347-352.

Jackson ML (1979) Soil Chemical Analysis. Department of Soil

Science, University of Wisconsin, Madison, WI, USA, pp. 468-

509.

Kapur S (1980) Pedogenesis and Classifi cation of Soils Developed on

Basalt Rock around the Mt. Karacadağ. Assoc. Professorship

Th esis. Çukurova University, Adana, Turkey, p. 115 (in Turkish

with English abstract).

Kavdır Y, Özcan H, Ekinci H, Yiğini Y (2004) Th e infl uence of clay

content, organic carbon and land use types on soil aggregate

stability and tensile strength. Turk J Agric For 28: 155-162.

Kleber M, Mikutta C, Jahn R (2004) Andosols in Germany -

pedogenesis and properties. Catena 56: 67-83.

Kurt S, Bünyamin A, Kurt H (2005) Sağlık Erenkaya (Konya

Batısı) yöresi volkanik kayaçların petrografi k ve jeokimyasal

özellikleri. Fırat Üniversitesi Fen ve Mühendislik Bilimleri

Dergisi 17: 190-204.

Moustakas NK, Georgoulias F (2005) Soils developed on volcanic

materials in the Island of Th era, Greece. Geoderma 129: 125-

138.


562

Nanzyo M, Shoji S, Dahlgren R (1993) Physical characteristics of

volcanic ash soils. In: Volcanic Ash Soils (Ed. S Shoji). Elsevier,

Amsterdam, pp. 189-207.

Özaytekin HH (2002) Karaman (Karadağ) Volkanitleri Üzerinde

Oluşan Toprakların Fiziksel, Kimyasal, Mineralojik Özellikleri

ve Sınıfl andırılması. Doktora Tezi. Selçuk Üniversitesi, Fen

Bilimleri Enstitüsü, p. 134.

Parfi tt RL, Kimble JM (1989) Conditions for formation of allophane

in soils. Soc Am J 53: 971-977.

Parfi tt RL, Wilson AD (1985) Estimation of allophane and halloysite

in three sequences of volcanic soils, New Zealand. In: Volcanic

Soils: Weathering and Landscape Relationships of Soils on

Tephras and Bazalt, Catena Suppl. Vol. 7 (Eds. EF Caldas, DH

Yaalon). Catena Verlag, Cremlingen, Germany, pp.1-8.

Peters DB (1965) Water availability. In: Methods of Soil Analysis, Part

I (Ed. CA Black). American Society of Agronomy, Madison,

WI, USA, pp. 279-285.

Prado B, Duwig C, Hidalgo C, Gómez D, Yee H, Prat C, Esteves

M, Etchevers JD (2007) Characterization, functioning and

classifi cation of two volcanic soil profi les under diff erent land

uses in Central Mexico. Geoderma 139: 300-313.

Quantin P, Dabin B, Boulean A, Lulli L, Bidini D (1985) Characteristics

and genesis of two Andosols in central Italy. In: Volcanic Soils:

Weathering and Landscape Relationships of Soils on Tephras

and Bazalt, Catena Suppl. Vol. 7 (Eds. EF Caldas, DH Yaalon).

Catena Verlag, Cremlingen, Germany, pp. 107-117.

Sanjurjo MJF, Corti G, Certini G, Ugolini FC (2003) Pedogenesis

induced by Genista aetnensis (Biv.) DC. on basaltic pyroclastic

deposits at diff erent altitudes, Mt. Etna, Italy. Geoderma 115:

223-243.

Schollenberger CJ, Simon RH (1954) Determination of exchange

capacity and exchangeable bases in soil-ammonium acetate

method. Soil Science 59: 13-24.

Schwertmann U (1985) Th e eff ect of pedogenic environments on

iron oxides. Adv Soil Sci 1: 171-200.

Shoji S, Dahlgren R, Nanzyo M (1993) Physical characteristics of

volcanic ash soils. In: Volcanic Ash Soils (Ed. S Shoji). Elsevier,

Amsterdam, pp. 189-207.

Shoji S, Fujiware Y, Yamada I, Saigusa M (1982) Chemistry and clay

mineralogy of Ando soils, Brown forest soils and Podzolic soils

formed from recent Towanda ashes, Northeastern Japan. Soil

Sci 133: 69-86.

Sigfusson B, Gislason SR, Paton GI (2008) Pedogenesis and

weathering rates of a Histic Andosol in Iceland: Field and

experimental soil solution study. Geoderma 144: 572-592.

Soil Survey Staff (1999) Soil Taxonomy. A Basic System of Soil

Classifi cation for Making and Interpreting Soil Survey. USDA

Agriculture Handbook No. 436, Washington DC, USA.

Soil Survey Staff (2010) Keys to Soil Taxonomy, 11th ed. USDA -

Natural Resources Conservation Service, Washington, DC,

USA.

Southard SB, Southard RJ (1989) Mineralogy and classifi cation of

andic soils in northeastern California. Soil Sci Am J 53: 1784-

1791.

USDA (2004) Soil Survey Laboratory Methods Manual. United States

Department of Agriculture - Natural Resources Conservation

Service, Soil Survey Investigations Report No. 42, Washington

DC, USA.

Vacca A, Adamo P, Pigna M, Violante P (2003) Genesis of tephra

derived soils from the Roccamonfi na Volcano, South Central

Italy. Soil Sci Soc Am J 67: 198-207.

Van Lagen B (1993) Manual for Chemical Soil Analyses. Department

of Soil Science and Geology, Wageningen University,

Netherlands.

Van Rast E, Utami SR, Verdoodt A, Qufoku NP (2008) Mineralogy of

a perudic Andosol in Central Indonesia. Geoderma 144: 379-

386.

Wada K (1985) Th e distinctive properties of Andosol. In: Advances

in Soil Science, Vol. 2 (Ed. BA Stewart). Springer, New York,

pp. 173-229.

Wada K (1989) Allophane and imogolite. In: Minerals in Soil

Environment (Eds. JB Dixon, SB Weed). Soil Sci. Soc. of

America, Madison, WI, USA, pp. 1051-1087.

Wada K, Kakuto Y, Ikawa H (1986) Clay minerals, humus complex

and classifi cation of four “Andepts” of Maui, Hawaii. Soil

Science Society of America Journal 50: 1007-1013.

White JL, Roth CB (1986) Infrared spectroscopy. In: Methods of Soil

Analysis, Part 1: Physical and Mineralogical Methods, 2nd ed.

(Ed. A Klute). Soil Science Society of America, Madison, WI,

USA, pp. 291-330.

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