The effect of forage management on carbon storage in pastureland and rotation
Degraded land with less than 1.5% organic carbon (class 4 and 5 land) in the Parkland of Western Canada has significant potential, from 5 to 15 Mg C ha-1 depending on management, for carbon storage with forages in the Parkland. The potential ranges 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. Nitrogen fertilizer increased organic carbon stored in reseeded pastures at Pathlow and Brandon relative to paddocks without fertilizer. Over a period of 12 years (1978-1989) in the Pathlow study, 21.9 Mg C ha- 1 (0-15 cm) was stored when N fertilizer was applied at an annual rate of 45 kg ha-1 compared to the control treatment, which was attributed to accumulation of plant debris and roots at the surface. Increases in organic carbon did not persist 10 years after N fertilizer was discontinued at the study at Pathlow, Saskatchewan. At Brandon, Manitoba, fertilized grass pasture stored 16.2 Mg C ha-1 (0-50 cm) compared to unfertilized bromegrass from 1994 to 1999. Long-term forage rotations at Melfort showed no significant difference in the wheat phase of a F-W-W-H-H-W rotation due to nitrogen fertilizer (147.3 Mg C ha-1 150.7 Mg C ha-1) over a period from 1957 to 1994. This was attributed to the high levels of soil carbon in soils at Melfort. Forages in rotation had no significant effect on organic carbon in a study at Glenlea MB conducted from 1992 to 1999, though a range from 110.8 to 145.7 Mg C ha-1 was observed. Significant differences may occur in the long term as organic carbon accumulates in the treatments at Glenlea.
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