Hydrologic Linkages to Subsurface Carbon

Sequestration in Florida

Acknowledgments:

Personnel who contributed to the Florida Soil Survey Program.

UF Soil and Water Science faculty and students.

Florida soil scientists.

Funding from USDA-NRCS and McIntire-Stennis

Publications related to topicHarris, W.G. 2001. Hydrologically-linked Spodosol formation in the Southeastern United States . p. 331-342. In J.L. Richardson and M.J. Vepraskas (eds.) Wetland soils: their genesis, hydrology, landscape, and separation into hydric and nonhydric soils. CRC Press, Boca Raton, FL.

Schaetzl, R., and W.G. Harris. 2011. Spodosols. p. 33-113 to 33-127. In: Handbook of Soil Science, 2nd ed. P.M. Huang, Y. Li and M.E. Sumner (eds.). CRC Press, New York.

Harris, W.G., and V.W. Carlisle. 1987. Clay mineralogical relationships in Florida Haplaquods. Soil Sci. Soc. Am. J. 51:481-484.

Harris, W.G., V.W. Carlisle, and K.C.J. Van Rees. 1987. Pedon zonation of hydroxy-interlayered minerals in Ultic Haplaquods. Soil Sci. Soc. Am. J. 51:1367-1372.

Harris, W.G., V.W. Carlisle, and S.L. Chesser. 1987. Clay mineralogy as related to morphology of Florida soils with sandy epipedons. Soil Sci. Soc. Am. J. 51:1673-1677.

Stone, E.L., W.G. Harris, R.B. Brown, and R.J. Kuehl. 1993. Carbon storage in Florida Spodosols. Soil Sci. Soc. Am. J. 57:179-182.

Harris, W.G., S.H. Crownover, and N.B. Comerford. 1995. Experimental formation of Aquod-like features in sandy coastal plain soils. Soil Sci. Soc. Am. J. 59:877-886.

Tan, Z., W.G. Harris, and R.S. Mansell. 1999. Watertable dynamics across an Aquod-Udult transition in Florida flatwoods. Soil Sci. 164:10-17.

Harris, W.G., and K.A. Hollien. 1999. Changes in quantity and composition of crystalline clay across E - Bh boundaries of Alaquods. Soil Sci. 164:602-608.Harris, W.G., and K.A. Hollien. 2000. Changes across artificial E - Bh boundaries generated under simulated fluctuating water tables. Soil Sci. Soc. Am. J. 64:967-973.

Harris, W.G., S.H. Crownover, and J. Hinchee. 2005. Problems arising from fixed-depth assessment of deeply-weathered sandy soils. Geoderma 126:161-165.

Harris, W.G., and C.A. Rischar. 2012. Factors related to Bh horizon depth for artificial and natural E- Bh sequences. Geoderma 189-190:502-507.

Other collaboratorsKafui Awuma, Scarlett Balboa, Chumki Banik, Rex Ellis, Sabine Grunwald, Wade Hurt, Brent Myers, Travis Richardson, Aja Stoppe

Coauthors

Color guide for doubt level

• Observations and data – require faith, but retain some doubt

• Ideas and inferences – require doubt, but retain some faith

Focus on one form of “deep C”

• Podzolization - pedogenic translocation & joint accumulation of C & metals:

– Eluviation – • loss

– Illuviation –• gain

• Podzolization => subsurface C sequestration

A

E

Bh

SHWT

Other pertinent terms

• Spodic* horizon – meets threshold podzolic C & metal accumulation

• Spodosol – soil order with Spodic horizon within 2-m depth

* Most Bh horizons in Florida meet Spodic criteria

Spodosol distribution worldwide

Commonly well drained

Mainly restricted toimperfectly-drained sites

What is the role of the water table in fostering Spodosol formation in Florida?

Randy Schaetzl

Dupont heavy mineral mine exposure – NE FloridaA huge C pool

>2m

Estimated 431 Tg C in Florida Bh horizons within 2 m

Deep, thick C pool mass not estimated

Potential C gain or loss tied to climate and sea level

How does this C accumulate?Earl Stone, Randy Brown, Ron Kuehl

Chelate-complex theory

Ex - Low molecular weight

Ex – Fulvic acid

Ex – Humic acid

Al & Fe

Negatively-charged OM

“Clouds” of hydrated counterions

Dispersion

Flocculation & immobilization

E

Bh

Complexation & mobilization

Line of Scrimmage

Soil Surface

Buchholtz

Eastside

Gainesville

P.K. Young

Oak Hall

C

Al

Theory – Gainesville style

Line of Scrimmage

Soil Surface

C

Al

Line of Scrimmage

Soil Surface

C

Al

Line of Scrimmage

Soil Surface

C & Al

Al

Line of Scrimmage

Soil Surface

C & Al

Al

Uuughh!

Soil Surface

E

A

Bh

… and so it is with Spodosols …- but clay moves too, not just metals?

C & Al

Al & C

Keith Hollien,Soil Survey Data

“Sandhills” – deep water table “Flatwoods” – shallow water table

Coated sand

Clean sand

Coatings

• About 2-8 % of soil mass• Similar proportions of silt & clay• Silt – mostly quartz• Clay – quartz, phyllosilicates, gibbsite, & oxides of Al & Fe• NOT predominantly “iron oxide coatings”, although …• Al- & Fe oxides serve as “cement”

Characteristics of Sand Grain Coatings

Shannon Chesser, Vic Carlisle

Sandhill summit

Edge of Spodosol

Oxalic acid stripped

sand

Oxalic acid had no effect

Landscape observations

“Toeslope”

Nick Comerford, Stan Crownover, Keith Hollien

Sandhill summit

Edge of Spodosol

Coated sand;

chroma ≥ 6

Coated sand;

chroma < 6

Landscape observations (cont.)

“Toeslope”

Inference: color gradient and acid vulnerability related to redox depletion of Fe

Sandhill summit

Higher “free” Fe

Lower “free” Fe

Landscape observations (cont.)

Hypothesis: Toeslope sand is predisposed to form Spodosol

“Toeslope”

Edge of Spodosol

Recipe for a Frankenstein “Spodosol”

• Predisposed coated sand

• Complexing organic acid

• Fluctuating water table (22 h & 2 h drained)

• A few weeks

• That’s it!

“E”

“Bh”

Metals & C depleted

Metals & C enriched

Notes:

• No “Spodosol” formed with free drainage

• Bh formation => less metals in leachate

• E thickness related to metal & clay content of original soil:

R² = 0.65

p < 0.001

0

2

4

6

8

10

12

14

16

18

20

0 10 20 30 40 50

Med

ian

"E

" T

hic

knes

s (c

m)

AAO Fe+Al (mM kg-1)

R² = 0.50

p = 0.007

0

2

4

6

8

10

12

14

16

18

20

0.0 1.0 2.0 3.0 4.0

Med

ian

"E"

Th

ickn

ess

(cm

)

Clay (%)

Chad Rischar

Right now, you’re probably asking yourself …

here & here?

… what happens between …

“Sandhills” “Flatwoods”AA

This happens

Kafui Awuma, Scarlett Balboa, Chumki Banik, Vic Carlisle, Rex Ellis, Wade Hurt, Travis Richardson, Zhengxi Tan, Bob Mansell

Sand grain coatings are again clues …

Ideas• Process requires a threshold duration of near-surface saturation

• Organic acids “chip away” at Al with each threshold event

• E & Bh expression increases with increasing frequency of threshold

• Self-defeating - proceeds to maximum expression

AA

Zhengxi Tan, Bob Mansell

Ideas (cont.)fr

equ

ency

of

thre

sho

ld

E thickness

Ideas (cont.)fr

equ

ency

of

thre

sho

ld

E thickness

Distance

Why is a fluctuating water table required? 1. Metal sources for Bh - metal oxides – stable on well-drained

landscapes

2. Redox partially depletes Fe on poorly drained uplands (“flatwoods”)

3. Al => less crystalline & more vulnerable to organic complexation

4. Al oxides destabilized upon reaching thresholds in frequency & duration of saturation whereby• Organic acid activities increase (e.g., microbial degradation rates ↓)• Vertical water flow decreases (favoring kinetics)

5. Al oxide dissolution releases all coating components

6. C moves Al, but Al eventually stops C within finer matrix of colloidal origin

Concluding Ideas

Concluding thought: What happens to C with climate change or artificial drainage?

Nick Comerford, Sabine Grunwald, Aja Stoppe, Brent Myers

In memory of two people who enriched my life

Dr. Earl StoneDr. Vic Carlisle

Thanks! Questions?

• Jeff Locuta’s image – Pedology 2012

Soil of a thousand faces …

Louis Mantini Oren Reedy?

Thanks!Questions?

Data that do NOT support presumptions of Bh being a “hardpan”

Means of selected data for Bh, Bh1, Bh2, and Bh3 horizons sampled during the Florida Soil Survey Program

SaturatedHydraulic

Conductivitycm/h

BulkDensityg/cm-3

OrganicCarbon

%Clay

%

Non-Ortstein(vfr or fr)

14.10n=440

1.50n=440

1.38n=466

3.50n=466

Ortstein(vfi or fi)

8.05n=43

1.51n=42

2.59n=43

5.71 n=43

Bh and Bt horizons as “hardpans”

Myakka Very friableMany fine & medium roots

Leon Firm to friableMany fine & medium roots

Immokalee Friable to looseCommon fine & medium roots

Wabasso friable

Common fine & medium roots

Bh horizon consistence & roots as described on OSDs of Alaquods of large extent

Data that do NOT support presumptions of Bh being a “hardpan”

Outline of talk• Introduction

– Pertinent terms– Perspective on deep organic C distribution– Environmental relevance of deep C– Extant theories that don’t address hydrology

• Florida observations• Experimental data• Field study data• Proposed mechanisms of hydrologic linkages

Drowned coastal Bh horizons ( Phillips & Ellis)

Evidence of sea level rise

Spodosol distribution Florida

Figure ???. Average C mineralized (g C per g SOC) over time for A- and Bh horizons from 155 Florida Spodosol Profiles.

Morphological & mineralogicalevidence of coating redistribution Clean

Coated

Coated

• Aquod to Psamment sequence moving up from the shore of a sandhill lake

• About a 10-m transect

… but why is a fluctuating water table required?

Florida Soil Survey Program data suggesting Bh is clay-enriched, too

Lake, etc. Candler, etc. St. Lucie, etc.

“Coated” “Uncoated” “Uncoated”

Has Fe & Al Has Fe & Al No Fe & AlSome P retention Some P retention No P retention

Grains un-strippedGrains un-stripped Grains stripped

Family “Coated” – “Uncoated” distinction

Coated vs. Clean Sand Grains (cont.)

Coated

Clean

Clean

Coated

Coated

Lakeland Myakka St. Lucie

… in Panhandle &N. Central Florida… no matter howdeep or thick

Coated = high HIVin clay

Clean = high quartz,

maybe smectitein clay

Sand

Sand

Layers1

2

3

Duette

St. Lucie

AA

CE

Bh

Bunk! That’s no Bh Oh, yeah!

Come over here and say

that!

Heavy mineral mining dredge macerates Bh …

Opening Pandora’s Box

… releasing C at large scale

• Varshovi & Sartain• McLean,Shober, & Ellis