Canadian Journal of Soil Science · 1997
The rate of carbon change in agricultural soils in Canada at the landscape level
Smith, W. N., Rochette, P., Monreal, C., Desjardins, R. L., Pattey, E., Jaques, A.
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The rate of carbon change in agricultural soils in Canada at…
Abstract
The Century model [a computer simulation of the dynamics of soil organic carbon (SOC)] was used to estimate the rate of SOC change in agricultural soil in Canada. The analysis was carried out on 180 Soil Landscapes of Canada (SLC) polygons, representing 15% of the SLC polygons within agricultural regions. The analysis was stratified into soil zones and into soil textural classes. For each sampled polygon, Century was run for 1 to 5 types of crop rotations under conventional-tillage as well as no-tillage, providing that no-till was used on at least 5% of the land. From the Century simulations, it was estimated that the overall rate of SOC loss from agricultural soils in Canada for 1990 was 39.1 kg ha −1 yr −1 This implies that 1.93 Mt of SOC (7.08 Mt of CO 2 ) was lost from agricultural soils in Canada. Compared to 1990, the SOC loss was estimated to have been greater by 11.9 kg ha −1 yr −1 in 1980 and 9.1 kg ha −1 yr −1 in 1985. The lower loss in 1990 was primarily due to the incorporation of no-till practices and reduction of summer fallow in the mid 1980s. In 1990, at the provincial level, Alberta had the highest rate of SOC loss at 74.5 kg ha −1 yr −1 followed by Manitoba with 66.1 kg ha −1 yr −1 In Ontario, Quebec, and the Atlantic Provinces the average provincial rate of SOC loss was less than 35 kg ha −1 yr −1 Higher SOC loss rates were typically found in soils with coarser texture and greater native SOC content. Key words: Carbon dioxide, greenhouse gas, Century model
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The Century model [a computer simulation of the dynamics of soil organic carbon (SOC)] was used to estimate the rate of SOC change in agricultural soil in Canada. The analysis was carried out on 180 Soil Landscapes of Canada (SLC) polygons, representing 15% of the SLC polygons within agricultural regions. The analysis was stratified into soil zones and into soil textural classes. For each sampled polygon, Century was run for 1 to 5 types of crop rotations under conventional-tillage as well as no-tillage, providing that no-till was used on at least 5% of the land. From the Century simulations, it was estimated that the overall rate of SOC loss from agricultural soils in Canada for 1990 was 39.1 kg ha −1 yr −1 This implies that 1.93 Mt of SOC (7.08 Mt of CO 2 ) was lost from agricultural soils in Canada. Compared to 1990, the SOC loss was estimated to have been greater by 11.9 kg ha −1 yr −1 in 1980 and 9.1 kg ha −1 yr −1 in 1985. The lower loss in 1990 was primarily due to the incorporation of no-till practices and reduction of summer fallow in the mid 1980s. In 1990, at the provincial level, Alberta had the highest rate of SOC loss at 74.5 kg ha −1 yr −1 followed by Manitoba with 66.1 kg ha −1 yr −1 In Ontario, Quebec, and the Atlantic Provinces the average provincial rate of SOC loss was less than 35 kg ha −1 yr −1 Higher SOC loss rates were typically found in soils with coarser texture and greater native SOC content. Key words: Carbon dioxide, greenhouse gas, Century model
The Century model [a computer simulation of the dynamics of soil organic carbon (SOC)] was used to estimate the rate of SOC change in agricultural soil in Canada. The analysis was carried out on 180 Soil Landscapes of Canada (SLC) polygons, representing 15% of the SLC polygons within agricultural regions. The analysis was stratified into soil zones and into soil textural classes. For each sampled polygon, Century was run for 1 to 5 types of crop rotations under conventional-tillage as well as no-tillage, providing that no-till was used on at least 5% of the land. From the Century simulations, it was estimated that the overall rate of SOC loss from agricultural soils in Canada for 1990 was 39.1 kg ha −1 yr −1 This implies that 1.93 Mt of SOC (7.08 Mt of CO 2 ) was lost from agricultural soils in Canada. Compared to 1990, the SOC loss was estimated to have been greater by 11.9 kg ha −1 yr −1 in 1980 and 9.1 kg ha −1 yr −1 in 1985. The lower loss in 1990 was primarily due to the incorporation of no-till practices and reduction of summer fallow in the mid 1980s. In 1990, at the provincial level, Alberta had the highest rate of SOC loss at 74.5 kg ha −1 yr −1 followed by Manitoba with 66.1 kg ha −1 yr −1 In Ontario, Quebec, and the Atlantic Provinces the average provincial rate of SOC loss was less than 35 kg ha −1 yr −1 Higher SOC loss rates were typically found in soils with coarser texture and greater native SOC content. Key words: Carbon dioxide, greenhouse gas, Century model