This document estimates reference soil organic carbon (SOC) values for Colombian mineral soils using IPCC methodology. It homogenizes soil and climate classifications between national systems and IPCC, and assigns default SOC reference values based on soil and climate type. The results indicate Andean soils under cold humid climates store more carbon than warmer tropical soils. The study recommends refinements to wetland soil, low/high activity clay, and climate classifications to better represent Colombian conditions and reduce over/under estimation of SOC. Next steps are to validate the reference SOC values with local data and assess carbon stock changes from land cover conversions.

1. ESTIMATION OF REFERENCE SOIL ORGANIC CARBON
(SOC) FOR MINERAL SOILS OF COLOMBIA
Neira M. Fredy H.1, Turriago Juan D., Berrio Viviana

2. 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

3. 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

4. Methodology
1 Soil Map
USDA Taxonomy
2 Climate zones
Caldas Lang
IPCC Soil
System
IPCC climate
zones
IPCC SOC ref. values
SOC
ref

5. 1. Homologation of soil map (USDA to IPCC)
Date
1. Organic
soils
1
Histosols? 2. Sandy soils
2
> 70% A &
< 8% Ar?
3. Wet lands
3
Aquic ?
yes
No
yes
No
yes
4. Volcanic
soils
4
Andisols?
No
yes
5. Spodic soils
5
Spodosols?
No
yes
7. High Activity
Clays (HAC)
6-7
Oll, ert;
No
yes6. Low Activity
Clays (LAC)
NS. No Soil
Start
0
ME, AFR,
MR
y
e
s
No
No

6. 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)

7. Tropical wet
Elevation
> 800m
TMA
> 12°C
Warm temperate
moist
MAP
> 1000
Yes
No
Yes
Yes
Warm temperate
dry
No
MAT > 1,5
No
Cool temperate
moist
PMA:
PET
> 1
Yes
Yes
Cool
temperate dry
Tropical
Montano
Start
MAT >
18°C
Yes
No
No
MAP >
4000 mm
Yes
Tropical moist
MAP >
2000 –
4000 mm
Tropical dry
Nival
No
Yes
No
2. Climate homologation (Caldas Lang – IPCC)
MAT = Mean Annual
Temperature
MAP = Mean Annual
Precipitation

8. Date
RESULT 1. Homologation of soil map (USDA to IPCC)
IPCC Soil Area (ha) %
Organics 579.511 0,51
Sandy soils 7.276.236 6,39
Wetland soils 14.131.937 12,41
Volcanic 8.324.948 7,31
Spodic soils 8.159 0,01
Law Activity
Clays
76.013.824 66,73
High Activity
Clays
4.323.411 3,8
Others 3.261.473 2,86

9. Direct IPCC Homologation. Adjusted IPCC Homologation
CLIMA (IPCC)
Polar dry
Cool temperate
moist
Warm temperate
dry
Warm temperate
moist
Tropical montano
Tropical dry
Tropical moist
Tropical wet

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

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

12. 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.

13. 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

14. 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

15. 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