CHINESE GEOGRAPHICAL SCIENCE Volume 2, Number 1, pp.18-29, 1992 Science Press, Beijing, China

ALFISOLS AND CLOSELY RELATED SOILS IN CHINA

Xiao Duning ( ~j ~ j ~ )

(Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110015, PRC)

ABSTRACT: Alfisols are important soils in China. They occupy about 1.25 million

km 2, or about 13% of the land area. In the current Chinese system of soil classification,

hurozem, yellow-brown earths, Baijiang (Planosol) soils and parts of drab soils. They

are mostly forested soils with an estimated 5-13 t / ha • yr of organic matter returned

to the soils from temperate mixed conifer and broad-leaved forest. In terms of elemen-

tal bio-cycling, Ca is prominent.

In a comparison of 30 profiles the average ratio of clay (B/ A) was 1.47 for

Cryoboralfs and Eutroboralfs; 1.88 for Hapludaifs and 2.53 for Paleudalfs. From

Eutroboralfs to Paleudalfs the average gain (or loss) in clay during soil development is

about a factor of seven.

The moisture regimes vary considerably between Hapludalfs, Cryoboralfs, and as-

sociated Cryaquepts, but the amount of water is always enough to cause significant

leaching. In the weathering, and pedogenesis processes TiO 2, MgO and Fe203 are ac-

cumulated, respectively, in both A and BA horizons; but SiO2 and AI203 tend to be

leached from the solum.

K E Y WORDS: alfisols, distribution, classification

I. I N T R O D U C T I O N

Alfisols have not been classified by Chinese soil scientists as one o f the soil orders in

the current Chinese system of soil classification. Dark brown forest soils, burozems,

ye l low-brown earths and drab soils in temperate China are identified as four major great

soil groups. According to the criteria given by soil t axonomy (1975), these soils should be-

long to Alfisols. Additionally, Baijiang soils (planosols) are identified as a special kind of

Alfisol, probably Albaqualfs 111. The present paper deals with the occurrence and properties

of principal Alfisols in China.

m l 8 - -

II. DISTRIBUTION AND CLASSIFICATION

Alfisols in China generally occur in broad regions through the cool temperate, warm

temperate and north subtropical climate zones. They occupy about 1.25 million square km,

about 13% of the land area (about the same percentage occurrence as Alfisols in U.S.).

They are distributed in the eastern provinces where monsoon climate prevails. In this region

the mean annual temperature increases from north to south and precipitation decreases

from east to west especially in the northern part. Due to the strong influence of the mon-

soon originating from the southeast dry and wet seasons are prevalent. Most precipitation

is concentrated in the months of July to October. December through April are usually dry

months. The simultaneous occurrence of high temperature and increasing rainfall is

favorable for base eluviation and clay formation (Table 1).

Table 1 Climatological data of Alfisol distribution in China

M A S T Precipitation Depth of Soil GDD E / P index Vegetation

(~ ) (ram) freezing (cm)

coniferous-deciduous, Boralfs - 1 - 6 2000-3000 600-1100 0.5-1.0 100-250

mixed forest

Hapludalfs 6-8 3000-4200 500-1200 0.5-1.0 50-100 deciduous forest

deciduous-even flaeudalfs 15-17 4200-5000 800-1300 0.5-1.0 0

green mixed forest

mesophytes; deciduous ustalfs 12-15 3200-4500 500-700 1.0-1.5 10-40

forest i

* E ~ P = m e a n a n n u a l e v a p o r a t i o n ( E P ) m e a n a n n u a l p r e c i p i t a t i o n

EP = 0.0018 (t +25)(100 - a )

t-average monthly temperature - C

a---average monthly humidity

* Cumulative degrees (C) above base, temperature of 10 C

We can distinguish four suborders and 13 great groups of Alfisols from approximate

equivalents in the Chinese soil classification (Table 2). This list is incomplete. Some Chinese

soil scientists t21 consider that the concept of Alfisols is too wide, because it includes not on-

ly eluviation and illuviation, but also decalcification and dealkalization (solodization) (soil

Taxonomy, 1975). Greatly different soils are placed in the same order, according to this

view. Alfisols in China are mostly under forest but some have been cultivated for a long

time.

m l 9 m

Table 2 Alfisol taxonomy (USDA, 1975) and approximate equivalents

in China, s current soil taxonomy

Soil Taxonomy Chinese soil name

Aqualf

Boralf

Udalf

Ustalf

Albaqualf

Oehraqualf

Umbraqualf

Natraqualf

Cryoboralf

Eutroboralf

Paleboralf

Agrudalf

Hapludalf

Paleudaif

Fragiudalf

Haplustalf

Paleustalf

Baijiang soil (Planosol)

Dark brown forest soil with Baijiang horizon

Gleyed dark brown forest

solonetz and soda saline

Dark brown forest

Cultivated yellow--brown soil

Cultivated brown earth

Yellow-brown soil, Burozem

Red-brown

Clay pan yellow-brown

Luvie drab

I l L N A T U R E O F P E D O G E N I C P R O C E S S E S

1. F o r e s t H u m i f i c a t i o n

The accumulation and decomposition of leaf litter and plant remains are the main con-

stituents of biological cycling between the forest cover and the soil. There are 5 - - 1 3

t / ha • yr of organic matter and 1.5--2 t / ha ° yr pure ash returned to the soils in temper-

ate mixed coniferand broad--leaved forest I31. Table 3 shows the ash composition of litter in

three kinds of forest (Nanjing Institute of soil science, 1982). The soils at the sites of pine

and oak are considered Boralfs and, at the site of birch---oak, Aqualfs.

01 and 02 are dynamic horizons that exhibit an annual cycle in some Boralfs. The ac-

cumulation of leaves and plant materials has a maximum in May and a minimum in Sep-

tember. There is a sharp decrease between August and September. The thickness of 0 hori-

zons ranges from 1 to 5 cm.

The ash content of litter in pine and oak forest ranges from 8 - - 1 8 % , in

which Si is 2.4-- 11.5%. The order of element abundance in the ash is

Si> Ca> AI> Fe> Mg> K> Mn> Na. Considerable Si accumulates each year from the lit-

ter. Bioabsorptivity can be expressed as the ratio of element percentage in the 0 horizon ash

to the same element in the A horizon, e.g., 12.4 for Ca and 0.2 for Na in selected profiles

- - 2 0 m

(Table 4). In general other elements follow as Mg> Mn> Fe> AI> Si> K> Na.

Table 3 The ash compesition of litter under different vegetation in Heilongjiang Province

Litter Oak Birch-oak Pine

element kg / ha ks / ha kg / ha

weight (dry) 11,000 9,070 13,230

Ash 11.40 1,914 17.61 1,552 15.32 2,026

N 1.25 137.5 1.05 134.0

SiO 2 10.50 1155.0 11.49 1021.0 7.34 971.1

Fe203 0.82 90.2 0.83 75.1 0.59 73.8

Ai203 1.06 116.6 1.42 139.2 1.01 132.1

MnO 0.11 12.1 0.23 20.1 0.06 7.4

P205 0.26 28.8 0.35 31.7 0.32 40. I

CaO 3.58 393.8 2.82 255.1 2.95 344.5

MgO 0.38 41.8 0.59 53.5 0.40 50.1

K20 0.28 30.8 0.41 35.2 0.41 52.1

Na20 0.09 9.9 0.06 54.2 0.05 6.3

Table 4 Biogeochemical characteristics of the O and A horizons for

two representative Boralfs (%)

Item Ash SiO 2 FezO 3 A120 3 MnO CaO MgO TiO 2 K20 Na20

Pine forest

Dry matter 7.84 2.40 0.70 1.57 0.17 2.14 0.41 0.23 0.02

0 horizon 100 30.66 8.94 20.04 2.15 27.26 5.28 2.96 0.20 Cryoboralf

A horizon 68.32 7.48 15.91 0.39 2.20 1.43 0.92

Bioabsorptivity" 0.45 1.20 1.26 5.51 12.39 3.69

Oak forest

Drymatter 17.40 10.50 0.82 1.06 0.11 3.58 0.38 0.28 0.09

O horizon 100 60.34 4.71 6.10 0.63 20.57 2.18 1.61 0.52 Eutroboralf

A horizon 67.31 5.61 16.64 0.50 2.27 1.19 0.77 2.95 2.57

Bioabsorptivity 0.90 0.84 0.37 1.26 9.06 1.83 0.55 0.20

* Bioabsorptivity ratios obtained as ratio of 0 horizon element to A horizon, e.g., for SiO 2, 0.45 = 30.66/ 68.323.

In the forested areas, the trees deliver the bulk of their annual production of organic

matter above ground, including the litter which is not as deeply incorporated as in

grass-covered soils. The decomposition of mull is largely by micro-organisms that trans-

form raw organic material into humus and mix leaf litter and humus with mineral soil to

shallow depths (2 -10 cm).

Table 5 shows the composition of humus in some representative Alfisols in China. The

ratio of humic acid to fulvic acid is an important index to reflect the activity of humus. It is

greatly different between Udalfs and Boralfs. In 4 Udalf profiles the ratios were all less than

- - 2 1

1. The percentage of free humic acid ranges from 35 to 73 but in these selected soils, signifi- E'[4] cant differences can not be shown. The extinction coefficient ( j is an index which reflects

the amount of humus and its degree of decomposition. It is generally correlated with the

percent C.

Table 5 The composition of humus in some representative Alfisols

C Percent C in ~ree ~H (%) Soil Locality H / F E *

(%) H F Total H

Eutro-Boralf Heilongjiang 5.05 2L8 12.7 1.84 44.5 1.85

hapl-Udalf Liaoning 1.70 15.7 26.2 0.60 34.9 0.69

Hapl-Udalf Tibet 4.96 23.4 31.5 0.74 52.6 1.33

Paleudalf Nanjing 1.02 12.4 28.3 0.44 73.4 1.24

Agrudalf Nanjing 0.96 20.4 33.0 0.62 44.1 1.80

Formation of an ochric epipedon has been virtually universal in these soils. Biocycling

of nutrients from subsoil to 0 and A horizons is an important process in both Boralfs and

Udalfs.

2. Clay Format ion and M o v e m e n t

Clay formation derives from the chemical weathering of the primary aluminosilicate

minerals. In the temperate regions in China, these weathering p roduc t s - secondary

alumino-silicates-maintain Stability in the solum. Concentration of clay in the argillic ho-

rizon follows removal of carbonates from the parent material of that horizon. Presence of

argillans showing optical orientation in thin section in the Bt is considered as the evidence

of eluviation of clay from the A horizon and its accumulation in the Bt horizon. In a com-

parison of 30 profiles the average ratio of clay (B/ A) was 1.47 for Boralfs, 1.88 for

Hapludalfs, and 2.53 for Paleudalfs.

Table 6 shows some chemical properties and clay mineral characteristics of Alfisols in

China. Bt horizons are identified clearly in four selected soils by clay percent. The index of

CEC/ clay of A horizons in Eutroboralfs is higher than in Paleudalfs because they have a

higher organic matter content. The ratios of silica to sesquioxides in the solum do not vary

significantly.

The most important processes affecting the mineralogical and chemical composition of

the Alfisol profile are in the transformation of the parent material through the formation of

clay from the nonclay fraction and the loss or gain of clay to or from the surrounding soil

materials [ 51 In this evaluation of soil development, nonclay fractions represent the

reactants, clay fractions represent the products. Table 7 lists some soil and clay chemical

analysis of three representative pedons. Using the Barshad method, we calculated the chem-

- - 2 2 - -

Tab

le 6

Ch

emic

al p

rop

ort

ies

and

cla

y m

iner

al c

har

acte

rist

ics

of

som

e A

lfis

ols

in

Ch

ina

®

Soi

l L

ocal

ity

CaC

O 3

B

.S.

CE

C

Cla

y ®

H

or.

pH

(%

) (%

) cr

nol

(H +

) K

g

(%)

CE

C

Cla

y m

ola

r ra

tio

Cla

y S

iO2/

A

I203

S

iO2

/ R

203

Cla

y

min

eral

®

Eu

tro

bo

ralf

H

eilo

nji

ang

A

6.4

0 84

.3

22.6

9 8.

8 2.

58

Bt

6.8

0 88

.7

11.6

2 16

.1

0.72

C

6.6

0 --

--

3.

8 --

3.26

2.

49

2.82

2.

02

3.10

2.

21

I, V

Hap

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Lia

oin

8

A

5.6

0 71

.2

28.1

6 11

.2

2.51

Bt

5.3

0 20

.2

23.2

2 30

.0

0.77

C

5.2

0 36

.8

14.8

2 12

.3

1,20

3.50

2.

60

3.10

2,

40

3.70

2.

60

H,V

Pal

eud

alf

An

hu

i

A

5.8

0 60

.4

7.15

10

.6

0.67

2.

83

Bt

4.5

0 52

.9

9.54

31

.5

0.30

2.

66

C

4.9

0 59

.8

9.80

27

,8

0.35

2.

56

2,31

2.

10

1.97

Q:)

Par

ent

mat

eria

l is

gra

nit

e

®

Cla

y =

1

u®

H

=

h

yd

rom

icas

; V

=

verm

icul

ite;

K

=

kaol

init

e; I

=

ill

ite

I t~

ical composition of the nonclay fraction. Table 8 gives the results o f a calculation of profile

development. The loss or gain in clay during soil profile development is calculated by ad-

ding the clay formed to the clay originally present at each horizon. It is most effective in il-

lustrating the mineralogical and chemical changes of the parent material in its transforma-

tion to the developing solum. From Eutroboralf to Paleudalf, this value (B horizon clay)

increased seven times (7.5-49.2) reflecting the trend of soil development.

Table 7 Chemical analyses of soil and clay for three representative Alfisol pedons

Depth Soil material (%) Clay (%) Non clay" (%) Soil Locality Hor.

(cm) SiO 2 Fo203 AI203 S i O 2 Fe203 AI203 SiO 2 Fe203 A!203

A 5-13 68.69 5.49 t7.42 50.39 1 4 . 3 1 28.22 70.46 4.64 16.38 Eutro- Heilong

Bt 25-58 67.88 5.89 17.53 50.39 13.38 30.20 71.24 4.45 15.10 boralf jiang

C 90-140 69.78 4.31 15.50 48.78 16.72 26.70 70.61 3.82 15.06

Hapludalf Liaoning

A 6 - 6 71.94 3.90 17.16 54.29 12.48 26.87 74.17 2.82 15.96

AB 6-16 73.49 3.57 16.29 53.91 14.39 26.14 75.43 2.50 15.32

Bt 35-45 69.03 5.93 19.99 52.88 14.26 28.55 75,95 2.36 16,32

BC 60-70 71.41 5.21 17.28 53.97 16.62 24.96 75.74 2.38 16.32

Paleudalf

A 0-13 30.13 1.15 12.60 45.83 9.61 27.56 28.27 0.15 10.83

AB 13-26 75.26 4.30 11.49 44.48 11.10 28.26 82.20 2.77 7.71

Btl 26-45 73.99 4.48 12.89 44.68 11.57 26.85 81.59 2.64 9,27

Bt2 45-68 67.22 6.09 15.88 45.94 12.29 29.35 77.01 3,24 9.69

C 68-108 65.71 7.59 16.00 43.38 13.69 28.70 74.31 5,24 11.11

* Compos i t ionofnonclay = lOOxcomposi t ionofso i l s - compositionofclayxpercentofcla 7 1 0 0 - percentclay

"composition ~ represents the amount of any elemental oxide in 100 g. of material

~percent clay" see Table 8

In Eutroboralfs and Hapludalfs, A horizons lose clay and B horizons gain clay. But in

Paleudalfs, there is a differential loss by leaching of materials, so that the A horizon is more

depleted, particularly in clay than is the Bt, but both are depleted (Table 8).

3. Moisture Regime

The moisture regime is an important property of the soil and a determinant of pro-

cesses that can go on in the soil. In Alfisols, the amount of water is enough to cause leach-

ing, some water moves through the solum at some time during the year and moves down to

the moist substratum. But the moisture regime varies considerably in these Alfisols.

Hapludalfs in China appear to have seasonal moisture cycles. There are two dry peri-.

ods (spring and early summer; fall) as well as two wet periods (winter and early spring; late

summer) each year. The moisture percent in the Bt is 12-16% (range of wilting percent) in

the dry period, and 23-30% (range of field capacity) in the wet period. The horizon below

60 cm maintains 28-22% (equal to or slightly less than field capacity) throughout most of

- - 24 - -

the year [~].

Cryoboralfs appear wet almost the whole year, without an obvious dry period. During

the subsoil thawing period (May to early June), soil moisture percent is high because of the

cover of largely undecomposed organic matter. The surface soil moisture is high compared

with the subsurface horizons. After removal of the forest, the general soil moisture levels

decrease [~l.

Another kind of moisture regime occurs in the associated Cryaquepts. The period of

frozen soil is so long (only unfrozen in August) that the lower solum does not thaw. The

surface soil moisture content is more than 70% most of the time from June through Octo-

ber. From mid-July, the ground water begins to rise to within 25 cm of the surface in the

rainy season.

T a b l e 8 Eva lna f lon of profile development of ~ 3 l ~ l o n s in Tab l e 7

by c h e m i c a l a n a l y s i s ( a f t e r B a r s l m d , 1964)

Depth Clay f F N F -hN Gain O O-IN Soil Profile Hor. K

(cm) or loss g / ks g / ks g / kg

A 5-13 8.8 7.2 1.03 7.2 3.8 11.0 - 2.2 96.1 99.9

Eutroboraif Bt 25-58 16.1 5.8 1.01 5.1 3.5 8.6 7.4 88.3 91.8

C 90-140 3.8 0 1.00 0 3.8 3.8 0 96.2 100

Hapludalf

A 6 - 6 11.2 4.8 1.04 4.3 22.4 26.7 -15.5 90.0 112.4

AB 6-16 9.0 1.0 1.01 0.9 22.7 23.6 -14.6 91.3 114.0

Bt 35-45 30.0 0.1 1.00 0.1 17.4 17.5 12.4 70.2 87.7

BC 60-70 19.9 0 1.00 0 19.9 19.9 0 80.1 100

Paleudalf

A 0-13 10.6 51.8 3.71 25.9 19.2 45.1 -34.5 49.9 69.2

AB 13-26 18.4 28.5 1.05 31.0 41.9 72.9 -54.5 108.8 150.7

Btl 26-45 20.6 28.0 1.05 29.4 40.4 69.8 -49.1 104.8 145.2

Bt2 45--68 31.5 20.4 1.06 16.6 31.3 47.9 -16.3 81.2 112.9

C 68-108 27.8 0 1.00 0 27.8 27.8 0 72.2 100

f = amoun t of clay formed from lOOg. nonclay of the parent material

K = proportionality factor

F = amoun t of clay formed resulting in present amoun t ofnonclay

N = amoun t of clay originally present in A horizon

O = amount o fnonc lay originally present in A horizon

f _ a - B b I00 s = a - a ~ Bb ~x b

a = % ofSiO20fthe nonclay fraction o f the C horizon

b = % ofFe2030f the nonclay fraction of the C horizon

a p = % of Si20 o f the clay formed in the A horizon

b p = % of Fe2030f the clay formed in the A horizon

a = % ofSiO20fthe nonclay fraction o f the A horizon

b = % ofFe2030f the nonclay fraction of the A horizon

- - 2 5 - -

IV. CHARACTERISTICS

Some similarities in the characteristics of Alfisols observed in China to those in other

parts of the world are as follows:

1. Most Alfisols of China are weakly acid or acid, except for some Ustalfs. The de-

composition of primary minerals, the formation of secondary minerals and the evaluation

of bases and clays through the solum are clearly evident. Table 9 shows the movement of el-

ements in weathering and pedogenetic processes Ti, Mg and Fe are accumulated,

respectively, in both A horizons and Bt horizons; but Si and AI tend to leach. Release of

iron from primary minerals and the dispersion of particles of iron oxide in increasing

amounts gives the soil mass brownish and reddish brown colors, often termed

braunification in China tsI. Table 10 shows further the eluviation of elements. The indices of

leaching-accumulation in the clay fraction tend to be as follows: SiO 2 tend to zero;

Fe2 O3 is - 2 to - 5 (light leaching); AI2 O3 is 2 to 16. In the whole soil, the indices are: SiO2

is about -3; Fe203 is 7 to 28; and A1203 is 5 to 24. SiO2 is leaching whereas Fe203 and

AI203 are accumulating. Albaqualfs exhibit clearly different indices with most elements,

especially SiO 2 and Fe203 [9]

Table 9 Movement of elements in weathering and pedogenesis process (Numbers

represent indices of element concentration in respective horizons)

Soil Profile Si Fe AI Ti M n Ca Mg K Na

A horizon (A / R)

l 0.87 3.73 1.29 1.56 2.37 7.68 4.34

Eutroboralf 2 0.91 2.36 1.62 4.76 2.00 4.46 18.30

and 3 0.97 1.28 1.07 1:33 7.00 1.54 1.61 0.87

Cryoboralf avg. 0.92 2.46 1.33 2.55 3.79 2.16 8.08

Element Enrichment Series Mg> Mn> Ti> Fe> Ca> AI> Si> K> Na

0.67

Hapludalf

4 0.95 1.71 1.16 3.78 2.00 3.38 5.56

5 0.99 2.27 1.05 16.5 0.83 2.18 3.25

avg. 0.97 1.99 1.11 10.14 1.41 2.78 4.40

SeriesTi> Mg> Ca> Fe> Mn> Ai> Si

Eutroboralf

and

Cryiboralf

B horizon (B / R)

1 0.80 4.45 1.45 2.08 1.00 1.52 4.43

2 0.90 2.47 1.75 4.86 1.60 3.00 11.79

3 0.98 1.34 1.12 1.28 1.13 0.68 1.45

avg. 0.89 2.71 1.44 2.74 1.24 1.73 5.89

Series Ng> Fe> Ti> Ca> AI> Mn> Si> K> Na

0.80 0.69

Hapludalf

4 0.91 2.58 1.35 5.22 1.40 1.33 9.29

5 0.96 2.98 1.18 9.75 0.67 1.94 3.34

avg. 0.94 2.78 1.26 7.48 1.03 1.64 6.32

Series Ti> Mg> Fe> Ca> AI> Mn> Si

* R horizon represents gresh rock which is granite.

- - 2 6 - -

T a b l e 10 E luv la t ion of e l e m e n t s in Alf isol pedouenes i s ( N u m b e r s r e p r e s e n t indices

o f l e a c h i n g - a c c u m u l a t i o n in whole soil or in c lay f rac t ion)

Soil Profde Si Fe AI Ti Mn Ca M s K Na

1 -7 .76 17.11 10.83 25.0 -137.5 ---406.4 2.00

2 -0.98 4.34 7.81 1.96 -25 .0 -48.7 -55 .4

Eutroboralf 3 0.84 4.75 5.10 -4 .10 -455 -127 -11.2 2.96 3.02

and 7 -4 .17 -0 .2 -2.65 10.27 -7 .69 11.91 0.58 15.53 18.54

Cryoboralf avg. -3 .02 6.50 5.27 8.28 -156.3 -142.5 -16.0 9.25 10.78

Series N a > K > Ti> Fe> AI> Si> MS> Ca> M n

4 -4 .2 33.6 14.1 27.6 -42 .8 153 40.2

5 -2 .9 23.7 11.8 7.7 -25 .0 -12.1 2.6

Hapludalf 6 -3.1 25.5 7.1 18.6 0 -13.9 5.7

avg. -3 .4 27.6 11.0 18.0 -22.6 -60 .0 16.2

Series Fe> Ti> MS> AI> Si> Mn> Ca

8 3.2 18.9 20.4 13.7 0 -55.3 2.5 41.2 - 2 4

9 -3 .0 19.6 34.4 -2 .8 46.6 -69 .0 19.6 16.5 -19.1

Haplusta l f 10 -7.2 17.4 16.0 4.7 37.5 8.6 21.9 0.4 -2 .5

avg. -2 .3 18.6 23.6 5.2 28.0 -38.6 14.7 19.4 -15.2

Series Mn> Ai> K> Fe> MS> Ti> Si> Na> Ca

11 11.57 -37.2 -46.0 12.8 50.0 -16.4 -75.6 5.5 39.9 Albaqualf

Series M n > Na> Ti> Si> K> Ca> Fe> AI> MS

* Indices calculated as ratio ( B - A / B) x 100 where B is the amoun t of element in Bt and A horizon, respectively.

T a b l e 10 Einv in t ion of e l e m e n t s in Alf isol pedogenes i s (cont inued)

Soil profile Si Fe AI Ti Mn Ca Mg K Na

in clay

1 -2 .19 -8 .76 18.67 14.29 -87.5 -36.4 -14.14

2 --0.98 4.34 7.81 1.96 -25.0 -48.7 -55.4 Eutroboralf

3 -4.33 -0.01 9.30 -17.9 -9 .0 0 -18 .6 -30.8 7.4 and

7 -0 .90 -3 .25 1-.97 9.19 5.0 22.54 2.26 -20.7 16.4 Cryoboralf

avg. -2.1 -1 .92 9.44 1.88 -29.1 -15 .6 -16.8 -25.7 11.9

Series Na> K > Ti> Fe> AI> Si> MS> Ca> Mn

4 -2 .66 5.88 13.9 -15.8 -133 -200 -21.3

5 -1.43 -13.6 31.3 2.5 28.6 -300 -1.2

Hapludalf 6 0.25 -4 .7 1.9 1.7 11.1 11.1 -19 .0

avg. -1 .28 -4.1 15.7 -3 .8 -31.1 -163 -13.8

Series Fe> Ti> MS> AI> Si> Mn> Ca

11 0.36 0.50 2.16 15.5 -216.7 -22.2 -4 .3 -16.9 36.8 Albaqualf

Series M n > Na> Ti> Si> K> Ca> Fe> AI> M8

2. The thickness o f the argillic hor izon is c o m m o n l y 10 to 30 cm. Angular or

subangular structure is strongly developed in the Bt hor izon .

D 27 m

3. The dominant clay minerals are hydromicas and vermiculite [m°]. Smaller amounts of

montmorillonite and kaolinite are observed. In the surface horizons, there is a residue of

weathered quartz and feldspars. Analysis of soil amorphous materials in Boralfs show that,

as a result of hydration and oxidation, there is an obvious accumulation of amorphous Si,

Fe and At in B and BC horizons [~]. The transformation of biotite to illite or vermiculite and

enrichment of clay in the B horizons indicates that there is an obvious illuviation process.

4. There are occasionally thick A horizons in which humus is abundant, especially in

Boralfs. The common range of organic matter in the A horizons is 6 to 12 percent in

Boralfs, and 1 to 3 in Udalfs; nitrogen is 0.17 to 0.36 percent in Boralfs; 0.006 to 0.15

percent in Udalfs. The carbon--nitrogen ratio is 12.1 to 14.4 in Boralfs, and 9.0 to 13.5 in

Udalfs (data not show).

5. Soil exchange capacity is rather high 20-30 cmol H+/ kg in surface horizons and

rapidly decreases to about 10 cmol H+/ kg in an albic horizon. Among exchangeable

cations, Ca is dominant (50-60% of total) and Mg is second (10-20%) [m2]. The ratio of

CEC / clay in the A and B horizons ranges from 1.24 to 3.20, respectively. The average ra-

tio in Boralfs is 2.79 and in Udalfs 1.83.

V. C O N C L U S I O N S

Probably due to the influence of the monsoon climate, Alfisols in China have some dif-

ferences compared with those in U.S.A. [13-t41. First, because the dry period is relatively long,

evapotranspiration exceeds precipitation in many areas. Boralfs are frozen to considerable

depth in winter, resulting in much reduced percolation so that eluviation and leaching ap-

pear to be relatively less than in many Alfisols of the U.S.A. at the same latitude. The E ho-

rizon is not as prominent in Alfisols of China.

Secondly, Quaternary glacial action is limited in China. The weathering crust and soils

are relatively old. Therefore, the movement of Fe203 and A120 3 in the profile, as well as

the relative accumulation of SiO2 in the surface probably reflect a long pedogenic process.

In some profiles these may be relict products °51.

Thirdly, the Bt horizons exhibit dynamic moisture and thermal regimes which appear

to extend to greater depths in Udalfs. Many B horizons in China average 30-80 cm in

thickness whereas in U.S.A. the average may be close to 20-50.

REFERENCES

[2] ~ N I , _ f . ~ # ~ , (3s), ~9s~.

28 - -

[3] ~ l g ~ , ~ l ~ g ~ m # / ~ l t X g ~ J ~ = ~ ~ t [ , ~ ± ~ , ~ , ~ t ~ , 1978.

[4] ]4,[~.-[-:Mi~:~f~Ji)i :, ~ J l ~ I ~ ' ~ / ~ / l ~ l ~ l ~ _ f . ~ l [ ] ~ , ~ [ - ~ , : l l ~ , 1982.

[5] I. Barshad, Chemistry of Soil Development, Rainhold Pub. caarp., New York, 1964.

[6] ~[IW~i~, ~ ] ~ [ [ ~ g ~ r ) ' ~ l l ~ ) ~ , ~ l ~ J c ~ . i [ ~ ] ~ i ~ : , 1963.

[7] ~I]~I~, @ ~ l ~ : ~ i ~ T ~ ) ~ l ~ J ~ l [ y / ~ i ~ l ~ l ~ - ~ , l l , ~ ~ , ~[[12}~l~j~t][~]/~:~lZ~i~/:,

1982.

[8] ~ ]~ j : , ! , ~ - : l l ~ b l ~ t L l : ~ l ~ f f f ~ l [ ~ / / ~ J ~ [ f l ~ , : 1 ~ , : 3 ~ , (3), 1959.

[9] ~ i q ~ , ~ l ~ l ~ i ~ , ~ l l { f f / ~ , _ ~ , 11, 1963.

[101 i.~l[:~, q~l~-l-_~1~J?_~'~Jl~J.@~, J ~ . i ~ [ , 1981, P.18-25.

[II] ~ll,-l-_~l[~)~, @[~:[~-[ - I$[ , ~[-~j~:fli~$JL ~ , 1980.

[12] ~ d p , f f p l ~ l X ~ - k ~ ] i j ~ , ~ g ~ : ~ , 1964.

[13] S. W. Buol, Soil Genesis and Classification, Iowa state Univ. Press, 1973.

[14] R. H. Rust, Alfisols, In I.P.Wildin8 et.al, Pedogenesis and Soil Taxonomy, Elsevier, Amsterdam, 1983.

[15] ~.~q~, )]~ilFf, q ] ~ , l ~ t ~ , ~ - l - ~ ] [ ~ - ~ : l : ~ : ~ [ ~ [ ¢ ~ ~ , : ~ g ~ [ , (1), 1981.

- - 2 9 - -