Influence of Agricultural Management on Soil Organic Carbon: A Compendium and Assessment of Canadian Studies

Canadian Journal of Soil Science 83:363-380 (2003)

A. J. VandenBygaart, E. G. Gregorich, and D. A. Angers
Agriculture and Agri-Food Canada
960 Carling Avenue
Ottawa, Ontario K1A 0C5

Abstract

To fulfill commitments under the Kyoto Protocol, Canada is required to provide verifiable estimates and uncertainties for soil oganic carbon (SOC) stocks, and for changes in those stocks over time. Estimates and uncertainties for agricultural soils can be derived from long-term studies that have measured differences in SOC between different management practices. We compiled published data from long-term studies in Canada to assess the effect of agricultural management on SOC. A total of 62 studies were compiled, in which the difference in SOC was determined for conversion from native land to cropland, and for different tillage, crop rotation and fertilizer management practices. There was a loss of 24 ± 6% of the SOC after native land was converted to agricultural land. No-till (NT) increased the storage of SOC in western Canada by 2.9 ± 1.3 Mg ha^–1; however, in eastern Canada conversion to NT did not increase SOC.

In general, the potential to store SOC when NT was adopted decreased with increasing background levels of SOC. Using no-tillage, reducing summer fallow, including hay in rotation with wheat (Triticum aestivum L.), plowing green manures into the soil, and applying N and organic fertilizers were the practices that tended to show the most consistent increases in SOC storage. By relating treatment SOC levels to those in the control treatments, SOC stock change factors and their levels of uncertainty were derived for use in empirical models, such as the United Nations Intergovernmental Panel on Climate Change (IPCC) Guidelines model for C stock changes. However, we must be careful when attempting to extrapolate research plot data to farmers' fields since the history of soil and crop management has a significant influence on existing and future SOC stocks.

Reprint available from Canadian Journal of Soil Science.

With permission from the authors, some of the data used in this study are available.

Table 1. Effect on soil organic carbon of converting native land to agricultural as a PDF file, an Excel spreadsheet, or a comma-delimited ASCII text file.
Table 2. Differences in soil organic carbon as a result of different agricultural management practices as a PDF file, an Excel spreadsheet, or a comma-delimited ASCII text file.

For related work, see:

VandenBygaart, A. J., E. G. Gregorich, D. A. Angers and U. F. Stoklas. (2004). Uncertainty analysis of soil organic carbon stock change in Canadian cropland from 1991 to 2001. Global Change Biology 10:983-994. Abstract.
VandenBygaart, A. J., X. M. Yang, B. D. Kay and D. Aspinall. (2002). Variability in carbon sequestration potential in no-till soil landscapes of southern Ontario. Soil & Tillage Research 65(2): 231-241. Abstract.

lak 02/2004