A micropedological study of the genesis of a gray-brown podzolic soil in southeastern Ontario (Canada)

Geoderma - Elsevier Publishing Company, Amsterdam Printed in The Netherlands

A M I C R O P E D O L O G I C A L S T U D Y O F T H E GENESI~ O F A G R A Y - B R O W N P O D Z O L I C SOIL IN S O U T H E A S T E R N O N T A R I O (CANADA)

G,K. RUTHERFORD

Department of Geography, Queen's University, Kingston, Ont. (Canada) (Received July 17, 1967)

SUMMARY S e l e c t e d p h y s i c a l and c h e m i c a l a n a l y s e s as well as thin s e c t i o n s t u d i e s w e r e c a r r i e d out on genetic h o r i z o n s of a gray-brown podzolic soil p r o f i l e of the Bondhead Sandy L o a m S e r i e s in Lennox and Addington. The analytical data indicate the p r e s e n c e of a s t r o n g l y e l u v i a t e d horizon o v e r l y i n g an illuvial horizon; m i c r o m o r p h o l o g i c a l evidence c o n f i r m s this and i n d i c a t e s the c o n s i d e r a b l e pedogenetic o r g a n i z a t i o n that has taken place d u r i n g soil f o r mation and s h o w s that the whole s e d i m e n t a r y l a y e r has been affected by pedogenesis. Whilst the p r e s e n c e of s i m i l a r skeleton g r a i n m i n e r a l o g y in the soil horizom~ is e v i d e n c e f o r the h o m o g e n e o u s n a t u r e of tiffs deposit, the lack of c o m p l i c a t e d void p a t t e r n s , p l a s m i c f a b r i c s and c u t a n s in the Ae c o m p a r e d with the B2t horizon, is r e l a t e d to the eluviation of the f o r m e r and illuviation of the l a t t e r . The C horizon r e p r e s e n t s the l e a s t a l t e r e d state of the p a r e n t material. INTRODUCTION G r a y - b r o w n podzolic s o i l s have a w o r l d - w i d e distribution in the t e m p e r ~te zone. In N o r t h A m e r i c a , t h e s e s o i l s a r e f o r m e d on c a l c a r e o u s p a r e n t m a t e r i a l s and a r e u s u a l l y a s s o c i a t e d with d e c i d u o u s and m i x e d c o n i f e r o u s - d e c i d u o u s f o r e s t vegetation. In s o u t h e a s t e r n Ontario they a r e a m o n g s t the m o s t p r o d u c t i v e and potentially p r o d u c t i v e a g r i c u l t u r a l soils. Although the p r o p e r t i e s and g e n e s i s of thes~ s o i l s have been d e s c r i b e d in c o n s i d e r a b l e detail in n o r t h e r n U.S.A. by Baldwin (1927), Marbut (1935), Cline (1949), F r e i and Cline (1949), T h o r p and S m i t h (1949), McCaleb and Cline (1950), McCal~b (1954) and Cann and Whiteside (1955) s i m i l a r i n f o r m a tion c o n c e r n i n g such soils in s o u t h e a s t e r n O n t a r i o is scant. However, Reid and Mathews (1954) and Mathews et al. (1955) have m a d e c o n t r i b u t i o n s to the study of the g e n e s i s and p r o p e r t i e s of t h e s e s o i l s in c e n t r a l Ontario and c o n s i d e r a b l e a r e a s have been m a p p e d in O n t a r i o and Quebec. G i l l e s p i e et al. (1963) c a r r i e d out the soil s u r v e y of Lennox and Addington County. The o b j e c t of this p a p e r is to p r e s e n t s o m e m i c r o p e d o l o g i c a l e v i d e n c e of the g e n e s i s of t h e s e s o i l s in s o u t h e a s t e r n O n t a r i o (Fig.l).

Geoderma, 1, 1967

277

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Fig.1. Location m a p of s o u t h e a s t e r n Ontario,

MATERIALS AND METHODS A soil m o n o l i t h (Plate I) and soil s a m p l e s w e r e c o l l e c t e d f r o m a s i t e on the f a r m of Mr. Milton Dunn n e a r C a m d e n E a s t , which was m a p p e d a s Bondhead Sandy L o a m by Gillespie et al. (1963). C h e m i c a l a n a l y s e s w e r e c a r r i e d out u s i n g s t a n d a r d m e t h o d s a c c o r d i n g to J a c k s o n (1962). Thin s e c tions of r e l e v a n t u n d i s t u r b e d sam,~les w e r e p r e p a r e d using s t a n d a r d impregna,tion techniques and e x a m i n e d wit~, a p e t r o g r a p h i c m i c r o s c o p e and d e s c r i b e d by methods a d v o c a t e d by B r e w e r (1964). The spatial r e l a t i o n s h i p s of the soil units w e r e i n v e s t i g a t e d using a b i n o c u l a r s t e r e o m i c r o s c o p e and the d e s c r i p t i v e t e r m i n o l o g y is that r e c o m m e n d e d by the Soil Survey Manual (United S t a t e s D e p a r t m e n t of A g r i c u l t u r e , 1951). Some r e l e v a n t analytical data a r e c o n tained in Table I. RESULTS AND DISCUSSION

Description of soil profile Situation: Farent material: Stoniness: Vegetation: Drainage:

~78

lower and mid-,~lope ~f long 2 ° slope. c a l c a r e o u s till with g n e i s s i c and g r a n i t i c s t o n e s and g r a v e l s up to 6 inch d i a m e t e r ; few l i m e s t o n e pebbles. at p r e s e n t , stoni.ness c l a s s 0. c l o v e r - g r a s s p a s t u r e in a r a b l e / p a s t u r e rotation. m o d e r a t e to i m p e d e d internal d r a i n a g e ; p o o r exte ~nal drainage.

Geoderma, 1, 1967

TABLE t Some c h e m i c a l and p h y s i c a l p r o p e r t i e s of Bondhead Sandy L o a m n e a r C a m d e n E a s t in s o u t h e a s t e r n Ontario, Canada Horizon

A1

A1/A e

Ae

B2t

C

HC

Mechanical a n a l y s i s (% of f r a c t i o n < 2 ram): 2,000-200 ~ 200-20 ~t 20-2 ~ 2 /~

15.3 45.5 29.6 9.6

n.d. 1 n.d. n.d. n.d.

21.7 33.4 19.5 25.4

9.6 20.6 23.2 46.6

11.8 29.3 17.0 41.9

20.0 50.0 9.4 21.1

Oven dry m o i s t u r e (%)

3.0

0.6

0.9

2.1

1.9

0.7

550QC (%)

9.9

2.5

1.7

4.2

4.2

1.6

Specific g r a v i t y ( g / c m 3)

2.5

2.3i

2~64

2.63

2.46

2.58

pH ( 1 : 2 , 5 H20 )

6.8

6.8

7.1

7.2

7.7

8.0

pH ( 1 : 2 . 5 N KC1)

6.9

L o s s on ignition

6.3

6.4

6.5

6.4

0.8

Cation exchange c a p a c i t y (mequiv./100 g soil)

12.05

9.50

7.50

21.75

30.50

Total b a s e s

12.10

9.06

4.42

21.82

36.61

Saturation (%) Dithionite- soluble m a t e r i a l (%) "Available" nutrients: (p.p.m.) N

100 0.6

95.5 n.d.

60.0 1.66

100 5.88

100 2.32

2.02

30

19

14

17

12

P

582

523

322

232

272

K

500 50

500

500

500

500

14 11 500

50

25

25

25

25

Mg 1non d e t e r m i n e d A 1 (0--5 i n c h e s )

IOYR3/I,2/1.5" very dark gray silty loam; weakly developed, fine granular structure; friable, sUghtly hard; few stones up to 1 inch diameter; dense mat of roots; abrupt change to horizon A e.

Ae (5--12 inches)

10YR7/2,7/1 light gray sandy clay; weakly developed coarse angular blocky structure, very firm, hard; high in fine roots; some metapedotubules with A 1 horizon material; few, medium, distinct 10YR7/4 (dry) mottles; very irregular diffuse boundary with extensions of this horizon into the B forming an albic horizon.

B2t (12-22 inches) 10YR3/2,4/I very dark grayish brown clay; very firm, hard; moderately developed fine angular blocky struc-. ture; few, faint, fine to coarse 10YR7/4 (dry) mottles; iMunsell Soil Colour Charts; m o i s t field colour r e n d e r e d fi~'st, followed by d r y colour. Geoderma, 1, 1967

279

PLATE I

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Photograph of soil monolith of Bondhead Sandy Loam. 280

Geoderma, 1, 1967

few 10YR7/3 (dry) very pale brown mottled cutans; gradual change to horizon C. C (22--28 inches)

10YR4/3,6/2 brown fine sandy clay to clay; sticky, plastic, friable, hard; weak, angular blocky structure; common, fine, distinct 10YR7/4 (dry) mottles; metapedotubules with A 1 horizon material; abrupt change to horizon HC.

HC (28--36+ inches)10YR4/3,6/4 brown sandy clay loam; friable, hard; many, coarse, faint to distinct 10YR6/6 (dry) mottles. Plate I is a photograph of the soil monolith as collected in the field and Plate H shows photographs of the A e and B2t horizons respectively. The following morphological features may easily be detected: (1) the marked, bleached A e horizon with its coarse angular blocky to almost massive structure; (2) the incursions of this horizon into the B horizon showing the albic nature of the former horizon. The structure of the A e contrasts significantly with: (3) the well developed, fine angular blocky structure of the B2t horizon. The morphological changes suggest that this profile was developed by the eluviation of a more or less homogeneous parent material forming tbe poorly structured, well developed, bleached A e horizon overlying the well structured textural B2t horizon.

Micromorphology The re sul t s of the microscopic examination of the thin sections from four horizons in the B3ndhead Sandy Loam are given in Tables II and HI and the soil micromorphology is interpreted on the basis of these results.

Skeleton grains Skeleton grains are the stable, not readily translocated, concentrated or reorganized material in the soil. The porphyritic aspect, and the grain morphology as well as the kind and nature of the major skeleton grains throughout the soil profile indicate that the parent material of the soil profile was reasonably homogeneous with depth. It is, therefore, reasonably certain that the horizon differentiation was developed by soil-forming proc e s s e s and is not the result of initial sedimentary processes.

Voids Voids are the pore spaces in the soil. The total void pattern cannot be completely deduced from one thin section but the evidence presented in the four thin sections which were examined and by examination under the stereo microscope is that the voids become finer and have a less complicated pattern with depth. The degree of void development d e c r e a s e s very markedly below the B2t horizon. The i n c r e a s e in clay content with depth gives less room for expansion and contraction on wetting and drying and hence the voids are finer and the pattern less complicated. Sleeman (1963) suggests that vertical cracking tends to predominato in the uppermost clay horizons and vertical cracking increa se s with depth. Geoderma, 1, 1967

281

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TABLE II Description of skeleton grains and voids in Bondhead Sandy Loam in Lelmox and Addington County (Ontario) Horizon Skeleton grains Voids A1

Ae

poE)hyritic, very uneven, fine to medium, angular to rounded, regularly distributed and unrelated; plagioclase, orthoclase, quartz and green hornblende with some opaque minerals

B2t

mainly intrapedal (< 75/z) and interpedal (5-30~0, curvedto regular ortho skewplanes; few, simple channels (< 75~) mainly (5-75 ~)curved and irregular and unorientated ortho skewplanes (few ~ 75~); few, simple and dendroid (30-751z) channels; some of orthovughs (>75bQ few (30-75~t) curved, mammilated regula~ly distributed and unrelated, unoricu,ated ortho skewplanes; few interconnectedand simple orthovughs (< 50~)

few curved regularly distributed and unrelated ortho planar voids ( ~ 40g) ; simple and interconnected orthovughs (< 75~)

C

Plasmic fabrics The p l a s m a of a soil is that p a r t which is capable of being moved, r e organized o r c o n c e n t r a t e d by the p r o c e s s of soil formation. Th.e p l a s m i c f a b r i c j s the organization of the constituents of the c o l l o i d - s i z e fraction. The p l a s m i c f a b r i c s a r e much m o r e complicated in the Ae and the B2t. The A1 and C h o r i z o n s have r e l a t i v e l y s i m p l e r f a b r i c s . B r e w e r (1964) s u g g e s t s that asepic f a b r i c s (Plate Ilia,e) such as o c c u r in the A 1 and C h o r i z o n s of this profile a r e f o r m e d e i t h e r by sedimentation, soil wetting, i n h e r i t a n c e or weathering of s e d i m e n t a r y rocks. As the p a r e n t m a t e r i a l of this soil is n e i t h e r an o l d e r soil nor c o m p o s e d of w e a t h e r e d s e d i m e n t a r y r o c k m a t e r i a l s it is unlikely that the aseplc f a b r i c s a r e inherited. However, s e d i m e n t a t i o n p r o c e s s e s , soil wetting and d r y i n g and the w e a t h e r i n g of prolate m i n e r a l s such as m u s c o v i t e e i t h e r singly o r in combination m a y produce a s e p i c f a b r i c s such as in this profile. B r e w e r (1964) p r o p o s e s that the c a u s e of sepic f a b r i c s and p a r t i c u l a r l y m a s e p i c , vosepic and skelsepic as well as omnisepic may be the p r e s s u r e and tension e f f e c t s produced by soil wetting and drying (Platel'fib,c). The a b s e n c e of such c o m p l i c a t e d p l a s m i c f a b r i c s in the A 1 and C horizons is c o n s i d e r e d to be due to the absence of such t e n sion e f f e c t s in t h e s e horizons, whilst the m o r e c o m p l i c a t e d f a b r i c s in the A e and B2t a r e believed to be a function of strong clay translocation and soiI PLATE II Photograph of Ae, Bit(upper) and Bt(lower) h o r i z o n s of Bondhead Sandy Loam p r o f i l e Geoderma, 1, 1967

283

FABLE III E)escrip~ion of plasmie fabrics and pedological featuz .~ "n Bondhead Sandy Loam in Lennox and ~.dington County (Ontario) ~[orizon Plasmic fabrics

Pedological features cutans

pedotubules and glaebules

strongly adhesive, limonitic and argillaceous plane and channel cutans; diffuse, strongly separated

nodules 100-800 /~ equant to well rounded; sharp boundary; limonitic argillaceous

argillasepic

A1 Ae

mainly argillasepic with minor amounts of omnisepic

papules few 100-509/~ lamellar; rounded pedotubules; simple strongly adhesive paraisotubule characterized by a concentration of slightly weathered prolate grains up to 0.1mm width with pale yellow opaque nodules having argil= lasepic plasmic fabric B2t

t~

maskelvosepic with patches of undulic

very common, simple strongly separated and adhesive skewplane limonitic ferriargillans; predominantly illuviation but probably some diffusio~ cutans

nodules: i rregul ar, sesquioxidie and argillaceous (0.05-1ram) with marked undulic plasmic fabric and diffuse boundaries

mainly silasepic to argillasepi¢: with minor moskelsepie

void and vugh with minor skew plane ferriargillans (mainly simple limonitic but some older hematitic and younger compound limonitie ferriargillans) diffuse boundary; strongly separated and adhesive

pedotubules: simple, strongly adhesive, eliptical meta- or paragranotubules; skeleton grains (5-20 #) are even, irregular, unorientated and unrelated with fewer twinned plagioclase than in surrounding material; plasma virtually absent nodules: few (200-100 manganiferous and sesquioxidic; convolute to tuberose; irregular; unrelated; porphyritic papules: limonitic, lamellar, spherical to amygdaloidal; irregular, up to 100

284

Geoderma, 1, 1967

PLATE m

, AI

A2

\ b

/

Bt

d

f

J

C

Micrographs of some horizons in a gray-brown podzolic soil in southeastern Ontario: a. silasepic fabric (x 100); b. disrupted cutans and skelsepic fabric (x 100); c. mosepic and void cutans (x 100); d. isotubule (x 35); e. asepic (× 35); f. granotubule (x 35). Geoderma, 1, 1967

28~

f o r m a t i o n p r o c e s s e s . Clay illuviaticn in the B2t h o r i z o n would i n c r e a s e the expansion p o t e n t i a l on wetting bu ~. at the s a m e t i m e d e c r e a s e the available space so tha~ i n t e r n a l p r e s s u r e s would p r o m o t e the d e v e l o p m e n t of c o m plicated p l a s m i c f a b r i c s . Cutans T h e s e have p r e v i o u s l y gone by such n a m e s as "clay skin" o r " t o n hautchen" but as many of t h e s e f e a t u r e s a r e n e i t h e r t r u e clay n o r t r u e skins, B r e w e r (1960) h a s s u g g e s t e d the n a m e cutan. Cutans a r e a b s e a t in the ,~1 horizon, few in the Ae, v e r y c o m m o n in the B2t and few in the C horizon. The Very s t r o n g d e v e l o p m e n t of illuviation s e s q u i o ~ d e a r g i l l a n s (true clay m i n e r a l cutans) in the B2t hor~-~on is indicative of m a r k e d clay t r a n s l o c a t i o n (Plate IHc). This is a function of soil d e v e l o p m e n t and llas p r o c e e d e d c o n t e m p o r a n e o u s l y with it. An i n t e r e s t i n g f e a t u r e is the compound a r g i l l a n which is o b s e r v e d in the C h o r i z o n and is d e s c r i b e d Ln Table HI. T h i s argillan is c o m p o s e d of a l t e r n a t i n g r e d and yellow a r g i U a n s in p o l a r i s e d light so it is i n f e r r e d that soil d e v e l o p m e n t in this h o r i z o n m a y have o c c u r r e d u n d e r two quite different e n v i r o n m e n t a l c~nditions. The r e d h e m a t i t i c a r g i l l a n s a r e usually c h a r a c t e r istic of a hot c h m a t e with a l t e r n a t e wet and d r y p e r i o d s v'ld quite d i f f e r e n t f r o m that p r e v a i l i n g today in a r e a s w h e r e typically y e l l o ~ Amonitic cutans f o r m . F u r t h e r work m a y t h r o w light on p a s t P l e i s t o c e n e c l i m a t e s of the area. The evi(~el~ce of thin s e c t i o n m i c r o s c o p y p r e s e n t e d by F r e i and Cline (1949) shows ~hat clay coatings (i.e., illuviation cutans) have f o r m e d in the B horizon of if,r a y - b r o w n podzolic soils in New York although the u l t i m a t e origin of the ~utanic m a t e r i a l was open to c o n j e c t u r e . McCaleb (1954) has s u g g e s t e d that the c h a r a c t e r i s t i c l a y e r i n g of t h e s e cutans is due to s u r f a c e tension effects. Pedotubules T h e s e a r e pedological f e a t u r e s having a t u b u l a r e x t e r n a l f o r m and s h a r p b o u n d a r i e s wish the e n c l o s i n g soil m a t e r i a l . The pedotubules r e c o r d e d frora the A e and C h o r i z o n s a r e different in c h a r a c t e r (Plate l i d being r e s p e c t i v e l y a granotubule and an isotubule. It is a g e n e r a l l y a c c e p t e d i n t e r p r e t a t i o n of p e d o t u b u l e s ( B r e w e r and Sleeman, 1963) that they o r i g i n a t e as faunal b u r r o w s and tunnels w h i c h a r e l a t e r f i l l e d with soil and M a t e r i a l f r o m v a r i o u s h o r i z o n s . The g r a n u l a r f a b r i c of many g r a n o t u b u l e s s u g g e s t s washing in of s u r f a c e m a t e r i a l o r m a t e r i a l f r o m a highly eluviated horizon. The s i m p l e , d e n s e l y p a c k e d isotubule ~.v the A e h o r i z o n contains v e r y u n i f o r m sized g r a i n s s i m i l a r to t h o s e skeleton g r a i n s o c c u r r i n g throughout the profile. The granotubule in t h e C horizon c o n s i s t s of fine u n i f o r m s k e l e t o n g r a i n s which a r e s o m e w h a t d i f f e r e n t in kind to t h o s e o b s e r v e d e l s e w h e r e in the profile. The p r e s e n c e of pedotubules is a c l e a r indication of the role, o/ten n e g l e c t e d , of soil fauna in p e d o g e n e s i s . T h e different kinds of p e d o t~:bules in the two h o r i z o n s s u g g e s t s that d i f f e r e n t s p e c i e s m a y be active in the r e s p e c t i v e horizons. G laebules Nodules a r e r e c o r d e d f r o m the Ae, B2t and C h o r i z o n s and a r e s e s quioxidic in n a t u r e . T h e s e d e v e l o p e d as a r e s u l t of s o i l - f o r m i n g p r o c e s s e s 286

Geoderraa, 1, 1967 •

. 4

and sesquioxidic deposition is m o s t intense in the B2t horizon w h e r e water table m o v e m e n t s probably m a k e the m o s t m a r k e d impression. In the C horizon manganiferous nodules are f o r m e d probably as the result of annual periods of water-logging in this horizon. The undulic fabric of the nodules in the B2t horizon is characteristic of soil materials high in iron (Brewer,

1964).

Papules The p a p u l e s a p p e a r to be l i t h G r e l i c t s d e r i v e d f r o m s h a l e r o c k s , l i m i t e d a r e a s of w h i c h o c c u r in t h e Umesto;~e to the n o r t h w e s t . The p o s s i b i l i t y of J ice m o v e m e n t f r o m t h i s d i r e c t i o n s h o u l d not be o v e r l o o k e d .

REFERENCES Baldwin, M., 1927. The gray-brown podzolic soils of the eastern United States. Trans. Intern. Congr. Soil Sci., 1st, Washington, D.C., 276-282. Brewer, R.B., 1960. Cutans; their definition, recognition and classification. J. Soil Sci., 11: 280-292. Brewer, R.B., 1964. Fabric and Mineral Analysis of Soils. Wiley, New York, N.Y., 470 pp. Brewer, R.B. and Sleeman, J.R., 1963. Pedotubules; their definition, classification and interpretation. J. Soil Sci., 14: 156-166. Cann, D.B. and Whiteside, E.P., 1955. A study of the genesis of a podzol-gTay-brown podzolic intergrade profile in Michigan. Soil Sci. Soc. Am. Proc., 19: 497-501. Cline, M.G., 1949. Profile studies of normal soils of N e w York, 1. Soil profile sequences involving brown forest, gray-brown podzolic, and brown podzolic soils. Soil Sci., 68: 259-272. Frei, E. and Cline, M.G., 1949. Profile studies of normal soils of New York, 2. Micromorphological studies of the gray-brown podzolic-brown podzolic soil sequence. Soil Sci., 68: 333-344. Gillespie, J., Wicklund, R.E. and Mathews, B.C., 1963. Soil survey of Lennox and Adding+on County. Rept. Ont. Soil Surv., Canada Dept. Agr., 36, 63 pp. Jackson, M.L., 1962. Soil Chemical Analysis, 3rd ed. Prentice-Hall, Englewood Cliffs, N.J., 498 pp. Marbut, C.F., 1935. Soils of the United Sta~es. In: O.E. Baker (Editor), Atlas of American Agriculture. U.S.D.A., Washington, D.C., 139-161. Mathews, B.C., Reid, R.F. and Olding, A.B., 1955. Genesis and morphology of the Oneida and Haldimand series-gray-brown podzolic soils in Ontario. Can. J. Agric. Sci., 35: 500-510. McCaleb, S.B., 1954. Profile studies of Jlormal soils of New York, 4. Mineralogical properties of the gray-brown podzolic-brown podzolic soil sequence. Soil Sci., 77: 319-333. McCaleb, S.B. and Cline, M.G., 1950. Profile studies of normal soils of N e w York, 3. Soil Sci., 70: 315--328. Reid, R.F. and Mathews, B.C., 1954. The genesis of the Oneida series in southern Ontario. Can. J. Agric. Sci., 34: 614--623. Sleeman, J.R., 1963. Cracks, peds, and their surfaces in some soils of the Riverine Plain, N e w South Wales. Australian J. Soil Res., 1(1): 91-103. Thorp~ J. and Smith, G.D., 1949. Higher categories of soil classification: order, suborder, and great soil groups. Soil Sci., 67: 117--126. United States Department of Agriculture, 1951. Soil Survey Manual - U.S. Dept. Ag~. Handbook, 18. Washington, D.C., 503 pp.

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