ESTIMATION OF REFERENCE SOIL ORGANIC CARBON (SOC) FOR MINERAL SOILS OF COLOMBIA

Neira M. Fredy H.1, Turriago Juan D., Berrio Viviana

Introduction

Colombia is located in the equatorial – tropical latitude with differences in altitude

Climate and edafo– diversity due to its climate, geology, relief, soil materials…

Estimating SOC reference is a challenge due to lack of data

Objectives

To estimate Soil Organic Carbon (SOC) for mineral soils using IPCC methodology as reference

Future uses: - Estimate emissions under land cover changes- Validate IPCC methodology for national scale

Methodology

1 Soil MapUSDA Taxonomy

2 Climate zonesCaldas Lang

IPCC Soil System

IPCC climate zones

IPCC SOC ref. values

SOC ref

1. Homologation of soil map (USDA to IPCC)

Date

1. Organic soils

1Histosols? 2. Sandy soils

2> 70% A &< 8% Ar?

3. Wet lands3

Aquic ?

yes

No yes

No

yes

4. Volcanic soils

4Andisols?

No

yes

5. Spodic soils5

Spodosols?

No

yes

7. High Activity Clays

(HAC)

6-7Oll, ert;

No

yes6. Low Activity Clays (LAC)

NS. No Soil

Start0

ME, AFR, MR

yes

No

No

Homologation steps- Typic Haplofibrist Organic (O)

- Typic Melanudands Volcanic (V)- Typic Quartzipsamment Sandy (S)- Oxic Dystrudepts LAC - Typic haplustoll HAC  

Weigh: 50% T. Haplustoll (HAC), 30% T. Haplofibrist (O), 20% T. Haplohemist (O) Organic (50%)/HAC 50%

Database with % of each soil type per unit

1. Homologation of soil map (USDA to IPCC)

Tropical wet

Elevation > 800m

TMA> 12°C

Warm temperate moist

MAP> 1000

Yes

No

YesYes

Warm temperate dry

NoMAT > 1,5

No

Cool temperate moist

PMA: PET> 1

Yes

Yes

Cool temperate dry

Tropical Montano

StartMAT > 18°C

Yes

No

No

MAP > 4000 mm

Yes

Tropical moistMAP > 2000 –

4000 mm

Tropical dry

Nival

No

Yes

No

2. Climate homologation (Caldas Lang – IPCC)

MAT = Mean Annual Temperature

MAP = Mean Annual Precipitation

Date

RESULT 1. Homologation of soil map (USDA to IPCC)

IPCC Soil Area (ha) %Organics 579.511 0,51

Sandy soils 7.276.236 6,39Wetland soils 14.131.937 12,41

Volcanic 8.324.948 7,31Spodic soils 8.159 0,01Law Activity

Clays 76.013.824 66,73

High Activity Clays 4.323.411 3,8

Others 3.261.473 2,86

Direct IPCC Homologation. Adjusted IPCC Homologation

CLIMA (IPCC)Polar dry

Cool temperate moist

Warm temperate dry

Warm temperate moistTropical montanoTropical dryTropical moistTropical wet

Date

Default reference Soil Orgnic C Stocks (SOC ref)for mineral soils (tonnes C ha-1 in 0-30 cm depth)

Date

Default reference Soil Orgnic C Stocks (SOC ref)for Wetland Mineral Soils (in 0-30 cm depth)

Date

Results: Reference Soil Organic Carbon (SOCr) for mineral soil

5.957,71 Gigaton C

Cold humid climate soils from the Andes stock more Organic C than warm, or tropical soils from Caribe, amazonas and Orinoco Regions.

Discussions: Soil Homologation

Wetland soils: plenty of soil types have “aquic” conditions and flooding time vary per year from 1 to more than 6 months.“Recommended to consider specifications for wetland soils”

LAC vs HAC soils: - Great part of mineral soils are neither LAC or HAC. Thus over/under- estimation of SOC.• Recommended to create an intermediate class

IPCC considers low precipitation differences between tropical wet and Tropical moist (1000 mm) when precipitation vary up to 14000 mm (wide range)IPCC does not considers a tropical arid class, (Guajira = Caribe).Climate zoning must be estimated using effective precipitation, specially in mountain regions where runoff occurs commonly

Climate considerations

Date

Use of Reference Soil Organic Carbon (SOCr)Next steps:

Validate with local data

Compare with land cover to estimate Soil Organic Carbon loss

Determine local factors of C stock and C loss

Thankyou very much

Muchas Gracias