Sink Potential of Canadian Agricultural Soils

• Published in: Climatic change 2004-08, Vol.65 (3), p.297-314
• Main Authors: Boehm, M, Junkins, B, Desjardins, R, Kulshreshtha, S, Lindwall, W
• Format: Article
• Language: English
• Subjects: Agreements; Agricultural land; Agricultural practices; Agriculture; Biomass; Carbon; Carbon dioxide; Carbon sequestration; Carbon sinks; Cattle; Climate change; Cover crops; Crop residues; Crops; Decomposition; Emissions; Emissions control; Farm buildings; Fermentation; Greenhouse effect; Greenhouse gases; International law; Kyoto Protocol; Land management; Land use planning; Livestock; Livestock production; Nitrous oxide; Soil erosion; Soils; Tillage
• ISSN: 0165-0009; 1573-1480
• DOI: 10.1023/B:CLIM.0000038205.09327.51

Net greenhouse gas (GHG) emissions from Canadian crop and livestock production were estimated for 1990, 1996 and 2001 and projected to 2008. Net emissions were also estimated for three scenarios (low (L), medium (M) and high (H)) of adoption of sink enhancing practices above the projected 2008 level. Carbon sequestration estimates were based on four sink-enhancing activities: conversion from conventional to zero tillage (ZT), reduced frequency of summerfallow (SF), the conversion of cropland to permanent cover crops (PC), and improved grazing land management (GM). GHG emissions were estimated with the Canadian Economic and Emissions Model for Agriculture (CEEMA). CEEMA estimates levels of production activities within the Canadian agriculture sector and calculates the emissions and removals associated with those levels of activities. The estimates indicate a decline in net emissions from 54 Tg CO2-Eq yr-1 in 1990 to 52 Tg CO2-Eq yr-1 in 2008. Adoption of the sink-enhancing practices above the level projected for 2008 resulted in further declines in emissions to 48 Tg CO2-Eq yr-1 (L), 42 Tg CO2-Eq yr-1 (M) or 36 Tg CO2-Eq yr-1 (H). Among the sink-enhancing practices, the conversion from conventional tillage to ZT provided the largest C sequestration potential and net reduction in GHG emissions among the scenarios. Although rates of C sequestration were generally higher for conversion of cropland to PC and adoption of improved GM, those scenarios involved smaller areas of land and therefore less C sequestration. Also, increased areas of PC were associated with an increase in livestock numbers and CH4 and N2O emissions from enteric fermentation and manure, which partially offset the carbon sink. The CEEMA estimates indicate that soil C sinks are a viable option for achieving the UNFCCC objective of protecting and enhancing GHG sinks and reservoirs as a means of reducing GHG emissions (UNFCCC, 1992). [PUBLICATION ABSTRACT]