Published on October 4, 2007
Carbon sequestration in pasture and forage systems: Carbon sequestration in pasture and forage systems A. Moulin, P. McCaughey, D. McCartney, S. Bittman, M. Entz, W.F. Nuttall Carbon sequestration in rotations with forages and pastures: Background Objectives Methods Carbon sequestration in rotations with forages Carbon sequestration in fertilized and unfertilized pasture systems Carbon sequestration in rotations with forages and pastures Definitions: Greenhouse gases: nitrous oxide (N2O), methane (CH4), carbon dioxide (CO2) Carbon Sequestration: Carbon stored in the soil as soil organic matter Carbon Storage: Carbon stored in the soil as plant debris, roots, and soil organic matter One tonne of carbon removes 3.667 tonnes of CO2 Definitions Carbon Sequestration in forages: Carbon Sequestration in forages Increases of 5.4 and 9.3 Mg ha-1 in soil organic carbon (SOC) over 27 years for two studies in smooth bromegrass grassland. (Malhi et al. 1997, Nyborg et al 1994, 1998) 1.2 to 2.0 Mg C ha-1 yr -1 were stored on soils with poor fertility (Agro.Manger Sept 99 p 7-8) 0.2 Mg C ha-1 yr -1 over 20 years for intensive management of grassland. (Bruce et al 1999) Objective: Objective To report organic carbon sequestered in pasture systems and rotations with forages. Discuss issues related to carbon sequestration in forage systems and pastures Slide6: Carbon Sinks Atmosphere Atmosphere Soil Management Management Fertilizer Rotation Forages Tillage Residue Sink Tap Drain Annual Cropping Systems: Annual Cropping Systems Comparison of zero and conventional tillage at 200 locations in the Brown, Dark Brown, and Black soils in Saskatchewan Approximately 150 sites with a field comparison, 45 replicated studies, 5 detailed studies Current Estimates of Carbon Sequestration: Current Estimates of Carbon Sequestration Published literature for zero vs conventional tillage indicates 0.2 Mg C ha-1 yr-1 over 15 years for agricultural soils Research shows higher levels possible for Black soils over 15 years Slide9: Annual Crops (15 years) Texture No - till vs Conventional (Mg C ha - 1 yr - 1 ) Continuous crop from Crop - Fallow (Mg C ha - 1 yr - 1 ) Coarse (sand) 0.2 0.5 - 0.6 Medium (loam) 0.3 0.5 - 0.6 Fine (clay) 0.4 0.5 - 0.6 Slide10: Carbon Sinks Atmosphere Atmosphere Soil Sink Tap Drain Management Management Fertilizer Rotation Forages Tillage Forage Studies: Forage Studies Forages in Rotation Melfort, Saskatchewan Glenlea, Manitoba Pasture Systems Pathlow, Saskatchewan Brandon, Manitoba Melfort Rotations: Melfort Rotations Established in 1957 at Melfort, Saskatchewan Silty clay soil, Thick Black soils Fertilized and unfertilized Fallow-Wheat-Wheat-Brome Alfalfa Hay- Brome Alfalfa Hay-Wheat Slide14: Carbon Sinks Atmosphere Atmosphere Soil Management Management Fertilizer Rotation Forages Sink Tap Drain Glenlea Rotations: Glenlea Rotations Established in 1993 at Glenlea, Manitoba Clay soil, Thick Black soils Rotations 1) wheat-pea-wheat-flax (W-P-W-Fl); 2) wheat (under seeded to sweet clover)-wheat-flax (W.Cl-W-Fl); 3) wheat- alfalfa (two years)-flax (W-Al-Al-Fl); and 4) a restored native tallgrass prairie Flax phase was sampled in 1999 Slide17: Carbon Sinks Atmosphere Atmosphere Soil Management Management Fertilizer Rotation Forages Sink Tap Drain Pathlow Pasture: Pathlow Pasture Established in 1978 at Pathlow, Saskatchewan Undifferentiated medium to moderately fine textured soil, Gray soils Treatments 0, 45, 90, 180 Kg ha -1 N; 0, 20 kg ha-1 P; 0, 23, 45 kg ha-1 elemental S Sampled in 1989 and 1999 Slide22: Carbon Sinks Atmosphere Atmosphere Soil Management Management Fertilizer Sink Tap Drain Brandon Pasture: Brandon Pasture Established in 1994 at Brandon, Manitoba Fine sandy loam soil, Black soils Treatments fertilized and unfertilized bromegrass, fertilized and unfertilized alfalfa and bromegrass Fertilizer applied at soil test recommendations Sampled in 1999 Slide25: Carbon Sinks Atmosphere Atmosphere Soil Management Management Fertilizer Forages Sink Tap Drain Carbon Sequestration in forages: Carbon Sequestration in forages Potential carbon sequestration ranged from 5 to 15 Mg C ha-1, over a period from 15 to 20 years, depending on fertility management of forages in pasture and initial levels of soil organic carbon.