How much Carbon Can be Sequestered by Organic-based Cropping Systems...

How much Carbon Can be How much Carbon Can be Sequestered by OrganicSequestered by Organic--based based Cropping Systems in MI Soils?Cropping Systems in MI Soils?

Senthil Subramanian, Sasha Kravchenko, Kurt Thelen,

Alvin SmuckerCSS, MSU

• Soil organic systems have a potential to increase C sequestration by soils.

• Reduction in atmospheric CO2 contributes an important component to the effort of reducing global warming.

• Providing organic producers with extra benefits from carbon credit trading?

Introduction

Objectives:

• To compare the quantities of total C in– Organic management with a winter leguminous

cover crop and– Conventional (chisel plow) management with

chemical inputs– No-till management with chemical inputs

• To identify topographical and soil conditions that lead to most rapid and effective C sequestration in organic management.

after long-term (>16 years) implementation.

Study Site:

Long Term Ecological Research Plots at KBS,MI

Treatments studied:- Tillage + chemical inputs (T1) - No-till + chemical inputs (T2)- Certified Organic: Tillage + Cover crops (T4)

Crop Rotation:Main crops: corn-soybean-wheatCover crops: hairy vetch or red clover

T2R5

T1R5 T4R5

T1R1 T2R2 T2R3

T4R3 T2R4

T4R2 T1R4T5R1

T5R2 T4R4

T4R1 T1R2

T2R1 T5R3

T1R3 T5R4

T1R6

T4R6

T5R6 T2R6

Lay out of the LTER Main site

T2R5

T1R5 T4R5

T1R1 T2R2 T2R3

T4R3 T2R4

T4R2 T1R4

T4R4

T4R1 T1R2

T2R1

T1R3

T1R6

T4R6

T2R6

Layout of the experimental site along with soil sampling locations and elevation

map

Results: Total C and N in the three studied management systems after 17 years of experiment

T1 T2 T4 T1 T2 T4

Results: Total C in the studied managements at topographical uphills and depressions

Results: Total C in conventional and organic managements at topographical uphills and depressions

Organic – T4In terms of increasing soil C organic management with cover crops in depressions worked the best.

Results: Total C in the studied managements at topographical uphills and depressions

Results: Total C in conventional and organic managements at topographical uphills and depressions

Results: Total C in the studied managements at topographical uphills and depressions

Results: Total C in conventional and organic managements at topographical uphills and depressions

ConclusionsOrganic system with cover crops was found to be as efficient in increasing soil C and N contents as conventional no-till management.Organic system with cover crops had significantly higher C and N levels than conventional chisel-plow management across the entire landscape.On average, each year the organic management with cover crops was adding 0.2 Mg/acre more of C to the top 30 cm of soil as compared to the conventional chisel plow.

ConclusionsHowever the gains in C due to organic management with cover crops were much more pronounced at the lower topography as compared to slopes and summits. At uphill positions each year the organic management with cover crops was adding 0.13 Mg/acre more of C to the top 30 cm of soil as compared to the conventional chisel plow.At depression positions each year the organic management with cover crops was adding 0.23 Mg/acre more of C to the top 30 cm of soil as compared to the conventional chisel plow.

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