Developments in Soil Classification, Land Use Planning and Policy Implications || Soil Classification and Genesis in Part of Khorasan Province

405S.A. Shahid et al. (eds.), Developments in Soil Classifi cation, Land Use Planning and Policy Implications: Innovative Thinking of Soil Inventory for Land Use Planning and Management of Land Resources, DOI 10.1007/978-94-007-5332-7_22, © Springer Science+Business Media Dordrecht 2013

Abstract Saline and sodic soils occupy an important part of Iran including the vast area in Khorasan province. Also due to secondary salinization, some of the arable lands are becoming salt-affected. It is important to characterize and classify these soils for better management and uses. Preliminary interpretation of aerial photos and using topographic map, the area was divided into different physiographic units, that is, dominantly piedmont alluvial plains and fl ood plains. In these units, 30 soil pro fi les were dug and described, and soil samples from each genetic horizon were collected for physical and chemical characteristics using standard USDA methods. The aridic and thermic were recognized as moisture and temperature regimes, respectively. The gypsiferous and saliferous marls are the parent materials, being main factor for soil salinization. Topography, wind erosion and human activities also contributed to soil salinization. Micromorphological studies have revealed the presence of secondary gypsum and calcium carbonate in some pedons, forming gypsic and calcic horizons, respectively. The soils are classi fi ed according to the USDA soil taxonomy. Two soil orders (Aridisols, Entisols) and six suborders ( calcids, salids, gypsids, cambids, fl uvents and orthents) have been identi fi ed in the area, and a new subgroup of sodic torri fl uvents is proposed.

Keywords Classi fi cation • Genesis • Khorasan province • Salinization • USDA

M. H. Sayyari-Zahan (*) Department of Soil Science, Agriculture Faculty, University of Birjand , 97175-331 Birjand , Iran e-mail: [email protected]; [email protected]

Chapter 22 Soil Classi fi cation and Genesis in Part of Khorasan Province

Mohammad Hassan Sayyari-Zahan

406 M.H. Sayyari-Zahan

22.1 Introduction

Salinization of land resources is a major impediment to their optimal utilization in many arid and semiarid regions of the world including Iran. Many countries have taken the initiatives to reduce soil salinization, but it is increasing at an alarming rate in the world. In this regard, the characterization, management and reclamation of salt-affected soils are gaining importance in many countries to bring these marginal lands into production to meet ever increasing food demand of the growing population. In Iran, about 25 × 10 6 ha of lands, representing 15% of the state area, are affected to varying levels of salinity and sodicity. Such lands constitute approxi-mately 30% of Iran’s plains and mild slopes and 50% of the lands with potential for irrigated agriculture. In Russia, China, India, Pakistan and Iran, saline soils are occurring on large areas. In these countries, most of the agricultural farms are irrigated with saline/brackish waters, which eventually have affected millions of hectares to become saline, although they have yielded abundantly but non-sustainably. Generally, in the arid and semiarid areas, low precipitation, high evaporation and storm activities bring the salts to the soil surface, a common phenomenon under hot climate.

The average annual rainfall ranges from less than 50 mm in the Central Plateau to more than 1,600 mm on the Caspian coastal plain, with a 250-mm national average. Owing to extremely hot summer, the average annual potential evaporation is very high, ranging from less than 700 mm along the Caspian Sea shore to over 4,000 mm in the deserts (Kavir-e-Loot). The problems of salt-affected soils have serious implications in the irrigated areas where about half of the land is prone to different levels of salinity (Cheraghi 2004 ) leading to national economic loss of more than 1 billion US$. Consequently, the dependency on irrigated agriculture is at stake in areas where land and water resources degradation has increased over time. Although salt-affected soils exist throughout Iran, slightly and moderately salt-affected soils are mostly found in the northern part, while soils with high salinity levels are prevalent in the central part.

In India it has been reported (Abrol 1972 ) that about 7 × 106 ha of India’s lands were affected by salinity and alkalinity due to insuf fi cient rainfall to leach salts. While studying salt-affected soils in Iraq, AlLayla ( 1978 ) has reported the origin of salts in certain parts of Iraqi soils due to salts carried via subterranean or phreatic water as well as salts transported via marine currents. In another study on Iraqi soils, Ayers ( 1960 ) described soil salinity development due to residual effects of parent material, slates, shales, limestone and gypsum as well as through drainage and evaporation.

Mahjoori ( 1975 ) studied saline and sodic soils in the lowlands of Iran. He collected soil samples from three soil series from the central and southern part of Iran. The study revealed the origin of salts from marly gypseous and saline deposits and their transportation to soils by water. In another study, pedogenesis of saline soils in an area of Roodasht in Esfahan revealed the role of parent material such as alluvium, in conjunction with slow drainage causing soils to become saline and sodic.

40722 Soil Classi fi cation and Genesis in Part of Khorasan Province

The present study was conducted with the objectives to determine physical and chemical characteristics of the zonal soils of Nishaboor plain and to classify soils using pedological taxonomy.

22.2 Materials and Methods

The study area is located in the Khorasan province (northeast of Iran). It is located between 59°, 30″ east longitude and 35°, 45″ north latitude, 85-km southwest of Mashhad (northeast of Iran) and is known as Neishabour Lower Dizbaud. The area is lying across the seasonal wind channel; that is why it is named Dizbaud (baud in Persian language means wind). At the time of study, some of the area was under cultivation.

By means of air photos and topographic maps (1:50,000 scale), the area was delineated into different physiographic units, and 30 pro fi le sites were selected. Soil pro fi les were dug and photographed to show in-depth horizons. Following to the description of soil pro fi les (Soil Survey Division Staff 1993 ) , soil samples were collected from different horizons for laboratory analysis. Soil samples were air-dried and passed through 2-mm sieve ( fi ne earth fraction), calcium carbonate (CaCO

3 )

equivalents, gypsum, soluble salts, pH, cation exchange capacity (CEC), exchangeable sodium percentage (ESP), soluble anions and cations, organic carbon and particle size distribution were determined using standard USDA methods (Burt 2004 ) .

22.3 Results and Discussion

The fi eld description of soil pro fi les and results from laboratory analyses of soil samples (pro fi le numbers 3, 7, 11, 13 and 21 located in the sloppy plain and 1, 4 and 27 located in the fl ood plain) revealed that the major source of the salts are marly, gypseous and salty formations present in the zone as parent materials which are carried into lower landscapes through the fl oodways in the region. Tables 22.1 and 22.2 present the results of physical and chemical characteristics of soil pro fi les.

In Iran, Persia’s tectonic formation has caused such soils to form. In a survey of saline and alkali soils of lowlands based on three soil series from the central and southern parts of Iran, Mahjoory ( 1979 ) attributed the origin of salts to parent materials of marly and gypseous deposits and their transfer through water and occurrence of salinization.

The increasing and decreasing trends of electrical conductivity of soil saturation extract (ECe) and sodium adsorption ratio (SAR) with respect to soil depth in the soil pro fi les have been shown in Figs. 22.1 , 22.2 , 22.3 and 22.4 in piedmont plain and Figs. 22.5 and 22.6 in fl ood plain. Where both ECe and SAR are increased with depth (Figs. 22.1 , 22.2 and 22.3 ), these are related to the origin of salts in the parent

408 M.H. Sayyari-Zahan Ta

ble

22.1

Ph

ysic

al a

nd c

hem

ical

cha

ract

eris

tics

of s

oil p

ro fi l

es f

rom

pie

dmon

t pla

in

Pro fi

les

no

Hor

izon

D

epth

(cm

) O

C

(%)

ESP

SAR

(m

mol

es

L -1

) 0.5

CaC

O 3

equ

ival

ents

(%

) E

Ce

(dS

m −

1 )

pH

SP

Part

icle

s pe

rcen

t

Soil

text

ure

Sand

(%

) Si

lt (%

) C

lay

(%)

3 A

1 0–

20

0.20

5.

6 4.

9 21

.4

1.5

8.4

38.1

37

.6

39.4

23

.0

L

B1

20–4

0 0.

14

12.6

10

.7

21.5

7.

1 8.

2 37

.2

39.6

43

.4

17.0

L

B

y1

40–5

5 0.

16

32.8

34

.1

21.6

44

.9

7.9

36.1

47

.6

37.4

15

.0

L

By2

55

–98

0.10

39

.7

45.7

23

.4

45.0

7.

8 41

.5

29.6

49

.4

21.0

Si

L

C1

98–1

07

0.08

41

.3

48.8

22

.2

46.8

7.

8 37

.7

71.6

17

.4

11.0

SL

C

2 10

7–13

0 0.

08

48.3

64

.3

22.7

61

.6

7.9

48.5

15

.6

57.4

27

.0

SiL

-SiC

L

C3

130–

150

0.06

42

.6

51.3

22

.0

42.5

7.

9 40

.7

37.6

47

.4

15.0

L

7

A1

0–20

0.

19

0.9

1.4

19.8

1.

4 8.

0 31

.2

39.6

33

.4

27.0

L

B

1 20

–48

0.15

2.

3 2.

4 18

.2

1.2

8.0

30.8

47

.6

29.4

23

.0

L

Bk

48–7

0 0.

12

6.8

5.8

24.4

6.

5 7.

9 29

.0

66.6

15

.4

18.0

SL

C

70

–102

0.

10

3.6

3.4

19.8

4.

1 7.

7 30

.6

71.6

12

.4

16.0

SL

2B

kb

102–

130

0.06

11

.5

9.7

25.4

4.

5 7.

8 55

.5

41.6

21

.4

37.0

C

L

11

A

0–23

0.

21

4.0

3.7

18.0

0.

8 8.

3 30

.0

34.2

47

.4

18.4

L

B

k1

23–6

5 0.

17

17.9

15

.7

24.8

4.

4 8.

2 35

.0

41.2

36

.4

22.4

L

B

k2

65–9

0 0.

10

7.7

6.5

20.2

7.

3 8.

1 32

.8

68.2

15

.4

16.4

SL

C

90

–150

0.

09

8.4

6.9

19.2

6.

5 8.

0 30

.0

62.2

18

.4

19.4

SL

13

A

p 0–

35

0.12

4.

3 3.

9 24

.2

3.5

8.0

32.1

63

.2

27.4

9.

4 SL

B

y1

35–6

0 0.

08

15.4

13

.2

23.5

9.

0 8.

0 30

.6

70.2

19

.4

10.4

SL

B

y2

60–8

3 0.

10

13.5

11

.8

22.5

9.

8 7.

8 30

.8

59.2

28

.4

12.4

SL

C

1 83

–125

0.

10

14.3

13

.0

22.7

14

.7

7.8

26.0

72

.2

16.4

11

.4

SL

C2

125–

150

0.04

22

.1

20.1

23

.2

19.4

8.

0 35

.6

46.2

31

.4

22.4

L

21

A

p 0–

25

0.22

35

.3

38.1

23

.2

37.2

8.

0 35

.5

44.2

39

.4

16.4

L

C

1 25

–50

0.15

30

.2

30.3

22

.6

30.1

8.

0 33

.5

50.2

31

.4

18.4

L

C

2 50

–70

0.12

14

.4

12.2

20

.8

9.8

7.9

27.0

74

.2

13.4

12

.4

SL

C3

70–1

40

0.08

10

.5

8.8

17.7

9.

1 8.

0 26

.1

80.2

4.

4 15

.4

SL

OC

org

anic

car

bon,

ESP

exc

hang

eabl

e so

dium

per

cent

age,

SA

R s

odiu

m a

dsor

ptio

n ra

tio, E

Ce

elec

tric

al c

ondu

ctiv

ity o

f so

il sa

tura

tion

extr

act,

SP s

atur

atio

n pe

rcen

tage

, L lo

am, S

iL s

ilty

loam

, SiC

L , s

ilty

clay

loam

, LC

loam

y cl

ay, S

L s

andy

loam

, CL

cla

y lo

am


Tabl

e 22

.2

Phys

ical

and

che

mic

al c

hara

cter

istic

s of

soi

l pro

fi les

fro

m fl

ood

plai

n

Pro fi

les

no

Hor

izon

D

epth

(cm

) O

C

(%)

ESP

SAR

(m

mol

es

L -1

) 0.5

CaC

O 3

equi

vale

nts

(%)

EC

e (d

S m

−1 )

pH

SP

Part

icle

s pe

rcen

t

Soil

text

ure

Sand

(%

) Si

lt (%

) C

lay

(%)

1 A

p 0–

37

0.38

26

.3

23.0

23

.1

13.0

7.

8 31

.6

55.7

32

.0

12.3

SL

C

1 37

–60

0.23

20

.1

21.0

20

.4

3.9

8.1

23.9

79

.7

10.0

10

.3

LS-

SL

C2

60–8

0 0.

15

22.5

20

.0

22.1

12

.3

7.8

42.5

15

.7

56.0

28

.3

SiC

L

2By

80–1

20

0.36

19

.5

13.0

23

.5

11.1

7.

7 42

.6

20.7

49

.0

30.3

C

L

2C

120–

145

0.15

13

.3

6.0

24.8

5.

0 7.

9 38

.4

35.7

38

.0

26.3

L

4

A1

0–15

0.

32

19.8

31

.7

22.6

33

.5

7.6

37.5

35

.7

42.0

22

.3

L

By

15–4

5 0.

23

22.9

59

.7

25.2

50

.6

7.9

39.3

46

.2

27.4

26

.4

L-S

CL

C

z 45

–75

0.31

27

.4

91.7

24

.0

79.5

8.

0 34

.0

55.7

24

.0

20.3

SC

L-S

L

2Byz

b1

75–1

08

0.28

29

.1

93.4

24

.5

88.8

8.

0 47

.9

16.2

52

.4

31.4

Si

CL

2B

yb2

108–

140

0.19

27

.5

32.8

25

.0

29.1

7.

7 43

.2

20.2

58

.4

21.4

Si

L

27

Ap

0–20

–

2.3

2.5

20.0

5.

0 7.

9 48

.4

20.2

48

.0

31.8

C

L-S

iCL

B

y1

20–5

0 –

19.7

17

.5

21.7

13

.0

8.0

50.0

24

.2

50.0

25

.8

SiL

B

y2

50–7

5 –

28.4

27

.8

23.6

27

.9

8.0

50.0

34

.2

37.4

28

.4

CL

C

1 75

–95

– 30

.1

31.1

24

.8

34.8

7.

9 39

.2

40.2

37

.4

22.4

L

C

2 95

–115

–

31.0

31

.4

23.1

36

.9

7.9

40.8

36

.2

42.4

21

.4

L

C3

115–

140

– 31

.4

32.1

24

.8

38.0

7.

8 38

.1

52.2

29

.4

18.4

SL

-L

OC

org

anic

car

bon,

ESP

exc

hang

eabl

e so

dium

per

cent

age,

SA

R s

odiu

m a

dsor

ptio

n ra

tio, E

Ce

elec

tric

al c

ondu

ctiv

ity o

f so

il sa

tura

tion

extr

act,

SP s

atur

atio

n pe

rcen

tage

, – =

not

rep

orte

d, S

L s

andy

loam

, LS

loam

y sa

nd, S

iCL

silt

y cl

ay lo

am, C

L c

lay

loam

, SC

L s

andy

cla

y lo

am, L

loam

, SiL

silt

y lo

am


material on which pro fi les are developed. In another study of Hamadan plain of Asadabad, Asadiyan ( 1989 ) has cited geological formations (e.g. schist and calcare-ous stones) being responsible for salinity and alkalinity development.

It has been observed that the regional topography has played a crucial role in salt transfer and accumulation. The results revealed that the soils with lower salinity and coarse textures are lying at higher altitudes of the region (pro fi les nos. 3, 7 and 13),

0

20

40

60

80

100

120

140

160

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70

ECe (dS/m) and SARD

epth

of

soil

(cm

)

ECeSAR

Fig. 22.1 In-depth trends of ECe and SAR in pro fi le no. 3 (piedmont plain)

0

20

40

60

80

100

120

140

0 1 2 3 4 5 6 7 8 9 10 11

ECe (dS/m) and SAR

Dep

th o

f so

il (c

m)

ECeSAR



whereas the soils higher in salinity and fi ne texture lie at lower altitudes of the region (pro fi le nos. 4 and 27). Having investigated the causes of soil salinity and alkalinity, Szabolcs ( 1985 ) came to the conclusion that these two phenomena were affected by various landscapes. High salinity at 75-cm depth (pro fi le no. 4, Fig. 22.6 ) has formed as salic horizon. Taimeh ( 1992 ) has demonstrated the consti-tution of salic horizon in the absence of subterranean and phreatic water effects and

0

20

40

60

80

100

120

140

160

0 2 4 6 8 10 12 14 16 18 20 22

ECe (dS/m) and SARD

epth

of

soil

(cm

)

ECe

SAR


0

20

40

60

80

100

120

0 10 20 30 40 50

ECe (dS/m) and SAR

Dep

th o

f so

il (c

m)

ECeSAR



concluded that this horizon has been shaped due to wind activity and alluvial deposits, and the maximum surface salinity is due to wind-borne (aeolian) deposits.

Besides the running waters, wind is the next important agent to transport salt crystals or salty materials from the upper parts to the low-lying lands. Barren surface and scarce vegetation cover enhance the wind action. This is evident from accumulated coarse fractions around the bushes in the area of pedon number 3, which lies on the

0

20

40

60

80

100

120

140

0 2 4 6 8 10 12 14 16 18 20 22 24 26

ECe (dS/m) and SARD

epth

of

soil

(cm

)

ECeSAR

Fig. 22.5 In-depth trends of ECe and SAR in pro fi le no. 1 ( fl ood plain)

0

20

40

60

80

100

120

140

0 10 20 30 40 50 60 70 80 90 100

ECe (dS/m) and SAR

Dep

th o

f so

il (c

m)

ECeSAR

Fig. 22.6 In-depth trends of ECe and SAR in pro fi le no. 4 ( fl ood plain)


central part of the plain. It has been estimated that nearly 50 cm of this pro fi le is fi lled with wind-deposited materials within an interval of 10 years.

The performance of plant species used as a management strategy for salt-affected soils can be improved by seed improvements: (1) pre-soaking seed treatment, that is, soaking of seeds in freshwater before sowing; (2) pretreatment of seeds for improved germination; (3) applying farm manure to the soil, where available; and (4) changing cropping patterns to avoid extreme stresses from hot and dry weather and high concentrations of salts (Qadir and Oster 2004 ; Qadir et al. 2008 ) . Soil salinity map of Iran showing different salinity zones as well as different landscapes is presented in Fig. 22.7 (Banie 2001 ) . The soil salinity map of Iran reveals 27% area affected to various level of salinity. Of 27%, 13% area is severely (<16 dS m −1 ) affected, 11% area is moderately (8–16 dS m −1 ) affected, and 3% area is slightly (4–8 dS m −1 ) affected (Fig. 22.7 ). These affected areas need careful management and reclamation for the optimum use for various purposes such as irrigated agriculture.

Fig. 22.7 Soil salinity map of Iran indicating area under salt-affected soils and other types of landscape (Modi fi ed from Banie 2001 )


22.3.1 Classi fi cation of Sloppy and Flood Plains Soils

Pro fi les nos. 7 and 13 are classi fi ed as calcids due the presence of calcic horizon. Pro fi le no. 7 is classi fi ed as Typic Haplocalcids and pro fi le no. 13 as Sodic Haplocalcids due to high ESP at a depth of 100 cm from soil surface. The soil classi fi cation results are presented in Tables 22.3 and 22.4 for piedmont and fl ood plains, respectively.

The sodic torri fl uvents is a newly proposed subgroup, with the following de fi nition: Sodic torri fl uvents are torri fl uvents that have an ESP > 15 or an SAR > 13 (mmoles L -1 ) 0.5 in all layers within the upper 50 cm which decrease with depth below 50 cm.

22.4 Conclusions

The development of irrigation systems in the area with deep water table had an ameliorative effect on the salinity and sodicity of the soils as the salts from the upper soil layers have been moved to the deeper layers. With variable levels of success, dif-ferent approaches, such as salt leaching and drainage interventions, crop-based management, chemical amendments and fertilizers, and integrated application of these approaches, have been used to enhance the productivity of salt-affected soils in the country. The soils revealed to fi t with Aridisols and Entisols orders and calcids, salids, gypsids, cambids, fl uvents and orthents suborders, accordingly. The new subgroup of sodic torri fl uvents has been proposed.

Table 22.3 Classi fi cation of soil pro fi les in piedmont plain (USDA 1994 )

Pro fi le no. Family Subgroup Order Proposed

3 Coarse loamy mixed thermic

Sodic Haplocambids Aridisols Sodic Torri fl uvents

7 Fine loamy mixed thermic Typic Haplocalcids Aridisols 11 Fine loamy mixed thermic Typic Haplocalcids Aridisols 13 Coarse loamy mixed

(calcareous)thermic Sodic Haplocalcids Aridisols

21 Coarse loamy mixed (calcareous)thermic

Typic Torriorthents Entisols Sodic Torriorthents

Table 22.4 Classi fi cation of soil pro fi les in fl ood plain (USDA 1994 )

Pro fi le no. Family Subgroup Order Proposed

1 Fine loamy mixed thermic

Typic Torriorthents Entisols Sodic Torriorthents


Gypsic Haplosalids Aridisols


Sodic Haplogypsids Aridisols


References

Abrol IP (1972) Saline and alkali soils in India, their occurrence and management. Central Soil Salinity Research Institute (CSSRI), Karnal

AlLayla AM (1978) Effect of Salinity on Agriculture in Iraq. J Irrig Drain Div 104(2):195–207 Anis Al-Layla M (1978) Effect of salinity on agriculture in Iraq. J Irrig Drain Div 104(2):

195–207 Asadiyan MS (1989) A survey of the soil salinity and alkalinity of Hamadan Plain of Asadabad.

MSc thesis, Pedology, College of Agriculture, Tehran University Ayers AD (1960) Saline and sodic soils of Spain. Soil Sci 90(2):133–137 Banie MH (2001) Soil map of Iran: land resources and potentialities. Soil and Water Research

Institute (SWRI), Tehran Burt R (ed) (2004) Soil survey laboratory methods manual. SSIR No 4., Ver 4.0. US Government

Printing Of fi ce, Washington, DC Cheraghi SAM (2004) Institutional and scienti fi c pro fi les of organizations working on saline agri-

culture in Iran. In: Taha FK, Ismail S, Jaradat A (eds) Prospects of saline agriculture in the Arabian Peninsula: proceedings of the international seminar on prospects of saline agriculture in the GCC countries 18–20 March 2001, Dubai, United Arab Emirates. Amherst Scienti fi c Publishers, Amherst, pp 399–412

Mahjoory RA (1975) Clay mineralogy, physical and chemical properties of some soils in arid region of Iran. Soil Sci Soc Am Proc 39:1157–1164

Mahjoory RA (1979) The nature and genesis of some salt-affected soils in Iran. Soil Sci Soc Am J 43:1019–1024

Qadir M, Oster JD (2004) Crop and irrigation management strategies for saline-sodic soils and waters aimed at environmentally sustainable agriculture. Sci Total Environ 323:1–19

Qadir M, Qureshi AS, Cheraghi SAM (2008) Extent and characterization of salt-affected soils in Iran and strategies for their amelioration and management. Land Degrad Dev 19:214–227

Soil Survey Division Staff (1993) Soil survey manual. USDA handbook no 18. USDA, Washington, DC Szabolcs I (1985) Assessment of soil salinity and alkalinity. Taxonomy and management of vertisols

and aridisols. In: Proceedings of the fi fth international soil classi fi cation workshop, Sudan, 2–11 November 1982. Part 1(198):253–261

Taimeh AY (1992) Formation of salic horizon without water table in an arid region. Soil Sci 154(5):399–409

USDA (1994) Keys to soil taxonomy, 6th edn. USDA-NRCS. US Government Printing Of fi ce, Washington, DC

Documents

Developments in Soil Classification, Land Use Planning and Policy Implications || Soil Classification and Genesis in Part of Khorasan Province