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Technical Thematic Report No. 16. - Soil erosion on cropland – introduction and trends for Canada

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Soil erosion on cropland: introduction and trends for Canada

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B.G. McConkey,Footnote[1] D.A. Lobb,Footnote[2] S. Li,Footnote[1] J.M.W. BlackFootnote[1] and P.M. KrugFootnote[3]

Canadian Biodiversity: Ecosystem Status and Trends 2010
Technical Thematic Report No. 16
Published by the Canadian Councils of Resource Ministers

Library and Archives Canada Cataloguing in Publication

Soil erosion on cropland: introduction and trends for Canada.

Issued also in French under title:
Érosion des terres cultivées : introduction et tendances au Canada.
Electronic monograph in PDF format.
ISBN 978-1-100-20600-4
Cat. no.: En14-43/16-2012E-PDF

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This report should be cited as:
McConkey, B.G., Lobb, D.A., Li, S., Black, J.M.W. and Krug, P.M. 2011. Soil erosion on cropland: introduction and trends for Canada. Canadian Biodiversity: Ecosystem Status and Trends 2010, Technical Thematic Report No. 16. Canadian Councils of Resource Ministers. Ottawa, ON. iv + 22 p.

© Her Majesty the Queen in Right of Canada, 2012
Aussi disponible en français

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Footnotes

Footnote [1]

Agriculture and Agri-Food Canada

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Footnote [2]

University of Manitoba

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Footnote [3]

Consultant

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Preface

The Canadian Councils of Resource Ministers developed a Biodiversity Outcomes FrameworkFootnote1 in 2006 to focus conservation and restoration actions under the Canadian Biodiversity Strategy.Footnote2 Canadian Biodiversity: Ecosystem Status and Trends 2010Footnote3 was a first report under this framework. It assesses progress towards the framework’s goal of “Healthy and Diverse Ecosystems” and the two desired conservation outcomes: i) productive, resilient, diverse ecosystems with the capacity to recover and adapt; and ii) damaged ecosystems restored.

The 22 recurring key findings that are presented in Canadian Biodiversity: Ecosystem Status and Trends 2010 emerged from synthesis and analysis of technical reports prepared as part of this project. Over 500 experts participated in the writing and review of these foundation documents. This report, Soil erosion on cropland: introduction and trends for Canada, is one of several reports prepared on the status and trends of national cross-cutting themes. It has been prepared and reviewed by experts in the field of study and reflects the views of its authors.

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Acknowledgements

Darrel Cerkowniak contributed several useful analyses and suggestions regarding land and activity data. We would also like to thank the reviewers of this report.

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Ecological Classification System – Ecozones+

A slightly modified version of the Terrestrial Ecozones of Canada, described in the National Ecological Framework for Canada,Footnote4 provided the ecosystem-based units for all reports related to this project. Modifications from the original framework include: adjustments to terrestrial boundaries to reflect improvements from ground-truthing exercises; the combination of three Arctic ecozones into one; the use of two ecoprovinces – Western Interior Basin and Newfoundland Boreal; the addition of nine marine ecosystem-based units; and, the addition of the Great Lakes as a unit. This modified classification system is referred to as “ecozones+” throughout these reports to avoid confusion with the more familiar “ecozones” of the original framework.Footnote5

Ecological classification framework for the Ecosystem Status and Trends Report for Canada.

map

Long Description for Ecozones+ map of Canada

This map of Canada shows the ecological classification framework for the Ecosystem Status and Trends Report, named “ecozones+”. This map shows the distribution of 15 terrestrial ecozones+ (Atlantic Maritime; Newfoundland Boreal; Taiga Shield; Mixedwood Plains; Boreal Shield; Hudson Plains; Prairies; Boreal Plains; Montane Cordillera; Western Interior Basin; Pacific Maritime; Boreal Cordillera; Taiga Cordillera; Taiga Plains; Arctic), two large lake ecozones+ (Great Lakes; Lake Winnipeg), and nine marine ecozones+ (North Coast and Hecate Strait; West Coast Vancouver Island; Strait of Georgia; Gulf of Maine and Scotian Shelf; Estuary and Gulf of St. Lawrence; Newfoundland and Labrador Shelves; Hudson Bay, James Bay and Fox Basin; Canadian Arctic Archipelago; Beaufort Sea).

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Agri-environmental indicators

As part of the National Agri-Environmental Health Analysis and Reporting Program, Agriculture and Agri-Food Canada has developed a suite of science-based agri-environmental indicators. These were first reported in 2000 (for 1981 to 1996), updated in 2005 (for 1981 to 2001), and most recently reported in 2010 (for 1981 to 2006) (Eilers et al., 2010). Three of these indicators are presented by ecozone+ as part of the Technical Thematic Report Series for Canadian Biodiversity: Ecosystem Status and Trends 2010. They are residual soil nitrogen (Drury et al., 2011), wildlife habitat capacity (Javorek and Grant, 2011), and this report on soil erosion on cropland.

All three of these agri-environmental indicators use data from the Canadian Census of Agriculture database. This database categorizes the agricultural landscape into four main cover types: Cropland, Pasture (broken down into Improved and Unimproved Pasture), Summerfallow, and All Other Land (All Other Land includes, for example, barnyards, woodlots, lanes, windbreaks, marshes, and bogs) (Huffman et al., 2006; Statistics Canada, 2008). The soil erosion and residual soil nitrogen Technical Thematic Reports focus on the agricultural land in production and therefore only use the first three cover types in their calculations (Unimproved Pasture is not included in the soil erosion analysis). Javorek and Grant (2011), on the other hand, include the All Other Land cover type when reporting on wildlife habitat capacity on agricultural land. The definition of “Cropland” in the soil erosion report differs from that used by the Canadian Census of Agriculture in that it includes the Census of Agriculture categories of Cropland, Improved Pasture, and Summerfallow when referring to “Cropland”. For these reasons, numbers presented for the total amount of agricultural land or Cropland or proportions of different cover types for an ecozone+ or region may differ slightly between the three agricultural reports prepared as part of the Technical Thematic Report Series for Canadian Biodiversity: Ecosystem Status and Trends 2010. Additional discrepancies may exist due to the methodology used to maintain anonymity of the data (see Eilers et al., 2010 for more information).

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Introduction

Soil erosion is the movement of soil. Erosion on cropland occurs naturally through the action of wind and water, which can be accelerated by some farming activities (for example, summer fallow, row cropping). High rates of wind erosion can occur on all landforms whereas the water erosion increases with slope and slope length. Erosion is also caused directly by the farming practice of tillage, which causes the progressive downslope movement of soil, resulting in soil loss from hilltops and soil accumulation at the base of hills. Soil erosion is a major threat to the sustainability of agriculture in Canada. It removes topsoil, reduces soil organic matter, and contributes to the breakdown of soil structure. These effects in turn adversely affect soil fertility, the movement of water into and from the soil surface and ultimately crop yields and profitability. Yields from severely eroded soils may be substantially lower than those from less eroded soil in the same field. Erosion can also have significant off-farm adverse impacts on the environment through the physical transport and deposition of soil particles and through the nutrients, pesticides, pathogens, and toxins that are released by erosive processes or carried by eroded sediments.

The soil erosion indicator is a risk indicator developed by Agriculture and Agri-Food Canada based on calculated rates of soil loss due to wind, water, and tillage erosion. These values are reported in five classes: very low (less than 6 t/ha/yr), low (6 to 11 t/ha/yr), moderate (11 to 22 t/ha/yr), high (22 to 33 t/ha/yr), and very high (greater than 33 t/ha/yr). Under current conditions areas in the very low risk class are generally considered capable of sustaining long-term crop production and maintaining agri-environmental health. The other four classes represent the risk of unsustainable conditions that call for soil conservation practices to support crop production over the long term and to reduce water quality impacts.

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Footnotes

Footnote 1

Environment Canada. 2006. Biodiversity outcomes framework for Canada. Canadian Councils of Resource Ministers. Ottawa, ON. 8 p.

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Footnote 2

Federal-Provincial-Territorial Biodiversity Working Group. 1995. Canadian biodiversity strategy: Canada’s response to the Convention on Biological Diversity. Environment Canada, Biodiversity Convention Office. Ottawa, ON. 86 p.

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Footnote 3

Federal, Provincial and Territorial Governments of Canada. 2010. Canadian biodiversity: ecosystem status and trends 2010. Canadian Councils of Resource Ministers. Ottawa, ON. vi + 142 p.

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Footnote 4

Ecological Stratification Working Group. 1995. A national ecological framework for Canada. Agriculture and Agri-Food Canada, Research Branch, Centre for Land and Biological Resources Research and Environment Canada, State of the Environment Directorate, Ecozone Analysis Branch. Ottawa/Hull, ON. 125 p. Report and national map at 1:7 500 000 scale.

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Footnote 5

Rankin, R., Austin, M. and Rice, J. 2011. Ecological classification system for the ecosystem status and trends report. Canadian Biodiversity: Ecosystem Status and Trends 2010, Technical Thematic Report No. 1. Canadian Councils of Resource Ministers. Ottawa, ON.

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Introduction