Potential for soil carbon sink enhancement in 3 northern Great Plains states

Institute of Atmospheric Sciences

South Dakota School of Mines and Technology

Potential for soil carbon sink enhancement in 3northern Great Plains states.

Karen UpdegraffPatrick R. ZimmermanDonna KlicheRick ClawgesWilliam J. CapehartPatrick KozakMaribeth Price



Big Sky Regional Partnership: MT, SD, ID

● Phase I assessment of terrestrial potential

● Modeled using CENTURY, GIS

● Agriculture is currently a net C sink

● MT has greatest land base but

SD has most cropland

● No-till in SD offers most

potential

Current:



Climate data

● National Climatic Data Center (NCDC) monthly average precip, min/max temperature since 1895 by station and climate division.

´0 200 400100 Miles

Climate Divisions in the Big Sky study area, from the National Climatic Data Center



Generation of soil texture grids

● SSURGO/STATSGO map unit data extracted into sand/silt/clay % grids. Bulk density from texture

● ENVI processing to generate soil classes

● Distributed soil classes within counties



Historical and current agricultural management: I

● Historical data from extension survey (SD), NASS crop databases, Census of Agriculture, anecdotal sources (types of crops, fertilizer use, irrigation)

● Conservation tillage and CRP data for 2002 from CTIC. No-till = ZERO tillage

● For point simulations, represent spatial proportions of crops as temporal series

● 6 timeblocks: 1900-35, 1936-45, 1946-65, 1966-82, 1983-89, 1990-

● Assume grassland for baseline period



Historical and current agricultural management: II● Assume no fertilizer before 1965

● Assume no irrigation unless >50% of crop was irrigated

● Scenarios

– ct2ct: continuous conventional tillage since 1900

– ct2nt: conventional, change to no-till in 1990

– ct2crp: conventional, change to CRP in 1990

– grz2grz: continuous grazing since 1990

– grz2crp: removal of grazing in 1990



Historical and current agricultural management III

● No public lands in simulation

● Runs to 2030 (stochastic weather after 2003)

● For each state:

– 8-10 climate divisions

– 17-19 soil classes

– 5 scenarios

= up to 900 separate simulations● Distribute results over county/soil class cells, sum for

county-level output

Attribute Aurora Beadle Bennettfips 46003 46005 46007zone 9 7 5ct2crp.s10 0 0 2180127ct2crp.s11 6188777 0 0ct2ct.s11 48145288 0 0

m2 applicable per county



Results: Land use distribution

State Crop-ConvTill

Crop-NoTill

Grazing CRP Total

Idaho 19,479 1,087 23,325 3,244 47,135 Montana 39,801 4,226 141,882 10,884 196,793South Dakota 51,986 14,664 105,440 5,752 177,842

km2 in each land use:

Cropland - CT Grazing/PastureGrazing/Pasture



Carbon stock changes since 1990Mean annual stock change, in MT/haState Conv-Till No-Till Grazing CRPIDMTSD

0.01 (0.13) 0.11 (0.17) 0.01 (0.01) 0.32 (0.06)

0.09 (0.03) 0.18 (0.05) 0 (0.01) 0.23 (0.04)

-0.02 (0.08) 0.2(0.05) 0.03(0.01) 0.3(0.04)

Variabilityin

annual C,Montana

C

, M

g ha

-1 y

r-1



State-level C stock trendsPredicted 40-year annual C-stock change (MTCE)State Current +25% CRP %diff +25% No-Till %diffID 287,124 312,978 10 289,071 1MT 788,544 818,251 4 801,317 2SD 662,802 704,928 6 909,212 37

Default +25% NT



Role of Ag Soil C in State GHG Budgets

Idaho Montana South Dakota

Fossil & Nonfossil Emissions 15.88 12.95 11.69

Forest LUC -3.26 -8.41 0.59Agriculture – Soil C -0.29 -0.79 -0.66Agriculture – Net 1.87 1.32 3.08TOTAL NET 12.34 3.76 11.61

State Annual Estimates for 2000, MMTCE



Cheyenne River Sioux Reservation Pilot Trade

≥ 62,000 MTCE/5yrs



Support provided by:

DOE Regional Carbon Sequestration Partnerships

Documents

Potential for soil carbon sink enhancement in 3 northern Great Plains states