david a. lobb · • adjustments --- rusle2 – interactions between factors – soil accumulation...

David A. Lobb Department of Soil Science University of Manitoba

Summit on Canadian Soil Health Soil Conservation Canada August 23rd, 2017 Guelph, Ontario

SOIL DEGRADATION: THE COST TO AGRICULTURE AND THE ECONOMY

ACKNOWLEDGEMENTS

Contributors:

Nasem Badreldin, University of Manitoba Marita Loro, Queens University Derek Brewin, University of Manitoba Tim Martin, Agriculture and Agri-Food Canada Brian McConkey, Agriculture and Agri-Food Canada Sheng Li, Agriculture and Agri-Food Canada

BACKGROUND

Question:

Why is a soil scientist talking about the economics of soil degradation?

To ensure sustainable crop food production at the farm scale and at the industry scale, by providing information on soil degradation and soil conservation in its most impactful form, economic.

BACKGROUND

Past Assessments of Costs: The costs of soil degradation in Canada were last assessed in the early 1980s.

Don F. Rennie’s 1985 paper: “Soil and Water Issues and Options in Canada”

Murray H. Miller’s 1986 paper "Soil Degradation in Eastern Canada: Its Extent and Impact”

BACKGROUND

annual values present values, 2.05x

With respect to public awareness, to government support through policies and programs, and to industry action, there has been a steady decline in interest in soil conservation.

A pervasive belief that “we know all there is to know about soil erosion and soil conservation”. And, that “the job is done and we need to move on”. A sense of fatigue has set in.

BACKGROUND

Move to justify soil conservation through protection of water quality and climate change.

BACKGROUND

There is a need to revisit these figures, to improve them and to update them to assess status and progress.

There is a more complete and accurate understanding of soil degradation processes – better models for assessment and prediction.

There are more comprehensive and accurate databases – which serve as better model inputs/outputs for assessment and prediction.

ASSESSMENT OF COST

Soil Degradation Processes: Focus on soil erosion given its extent and severity.

ASSESSMENT OF COST

Economic Impacts: Focus on the direct impacts of soil erosion on crop production and market value.

Not the indirect impacts.

Not the off-field impacts.

ASSESSMENT OF COST

Assessment and Prediction Models: Agri-Environmental Indicators Models: AAFC’s AEIP, NAHARP, SMP

Methods: Assessment and Prediction Models

National Agri-Environmental Health Analysis and

Reporting Program (NAHARP)

Integrate

Economics Agri-Environmental

Indicator (AEI)

Environmental

Valuation

Soil Quality

Soil Salinity

Tillage Erosion

(TillERI) Water Erosion

(WaterERI)

Wind Erosion

(WindERI) Total Soil Erosion

(SoilERI)

Soil Organic

Carbon Soil Erosion

+ + =

Water Quality Air Quality Others

Trace Elements

Soil Landscape Canada (SLC) Polygon, 10,000 – 1,000,000 ha

TillERI

Erosion Models

Landform

National Soil

Database

(NSDB)

Census of

Agriculture

1981- 2016

Soil,

Topography

Climate

Stations

Long Term

Climate Data Crop type,

Tillage

Up

Mid

Low Dep

WaterERI WindERI

SoilERI

Province

Canada

Data inputs

Aggregation

Aggregation

Aggregation

Methods: the framework of SoilERI

Methods: source data

• Soil

– National Soil Database (NSDB), SLC polygons

• Land use

– Census of agriculture

• 1981 - 2016

– Crop type

• Corn, cereal, forage …

– Tillage system

• Conventional

• Conservation

• No-till (direct-seeding)

• Climate

– Long term climate stations

• Topography

– Nominal info in NSDB and SLC polygon • Landform type: surface form and slope class

– Terrain analyses of typical sites • Nominal topo info to two-dimensional hillslopes

National Soil

Database

(NSDB)

Census of

Agriculture

1981- 2006

Soil,

Topography

Climate

Stations

Long Term

Climate Data Crop type,

Tillage

Methods: source data

849

89

162 Ecoregions

Ecodistric ts

Ecozones

SLC Polygons (#89 = 0.13 million ha)

Canada

(#849 = 0.9 million ha)

(#162 = 3.3 million ha)

(Prairie = 6.5 million ha)

Figure1: Map of the province of Manitoba illustrating the spatial framework of biophysical data in Canada. Source: Agriculture and Agri-food Canada.

Agriculture and Agri-Food CanadaAgriculture et Agroalimentaire Canada

Manitoba

0 250 500 1000

Projection Azimutal de Equi-aire de Lambert

0 500250 750 1000 1500

Lambert Azimuthal Equal Area Projection

ECHELLE ESCALA SCALE1: 45 000 000

miles

Kms.

Proyeccion Azimultal de Equi-area de Lambert

15

1

1

1

1

2

2

2

2

2

2

2

7

7

3

6

3

3

5

55

5

5

5

5

8

9

9

6

10

6

7

7

11

10

10

6

13

12

13

12

14

13

14

15

14

14

4

COMMISSION DE

CO

COMISION PARA LA

COOPERACION AMBIENTAL

COMMISSION FOR

ENVIRONMENTAL COOPERATION

CCE

CCA

CEC

OP RATION ENVIRONNEMENTAL

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

NIVEAU I. NIVEL I. LEVEL I

CORDILLERE ARCTIQUECORDILLERA ARTICAARCTIC CORDILLERA

TOUNDRATUNDRATUNDRA

TAIGATAIGATAIGA

PLAINE D'HUDSONPLANICIE DE HUDSONHUDSON PLAIN

FORETS SEPTENTRIONALESBOSQUES SEPTENTRIONALESNORTHERN FORESTS

MONTAGNES FORESTEES DU NORD-QUESTMONTANAS BOSCOSAS NOROCCIDENTALESNORTHWESTERN FORESTED MOUNTAINS

FORET MARITIME DE LA COTE OCCIDENTALEBOSQUE COSTERO OCCIDENTALMARINE WEST COAST FOREST

FORETS TEMPEREES DE L'ESTBOSQUES TEMPLADOS DEL ESTEEASTERN TEMPERATE FORESTS

GRANDES PLAINESGRANDES PLANICIESGREAT PLAINS

DESERTS DE L'AMERIQUE DU NORDDESIERTOS DE NORTEAMERICANORTH AMERICAN DESERTS

CALIFORNIE MEDITERRANEENNECALIFORNIA MEDITERRANEAMEDITERRANEAN CALIFORNIA

HAUTES TERRES SEMI-ARIDES MERIDIONALESELEVACIONES SEMIARIDAS MERIDIONALESSOUTHERN SEMI-ARID HIGHLANDS

SIERRAS TEMPEREESSIERRAS TEMPLADASTEMPERATE SIERRAS

FORETS TROPICALES SECHESSELVAS CALIDO-SECASTROPICAL DRY FORESTS

FORETS TROPICALES HUMIDESSELVAS CALIDO-HUMEDASTROPICAL WET FORESTS

Limite internationaleLimite internacionalInternational boundary

Limite de regions Niveau ILimite de regiones Nivel IRegion boundary Level I

Figure 2: Ecozones of North America. Source: Commission for Environmental Cooperation.

Methods: landform model • 19 landform types

– 7 surface forms

– 1 – 4 slope classes

• 4 segments (some only have 3)

– Up, Mid, Low and Dep

– length and slope gradient

• Calculation unit:

– Landform (hillslope)

– Multiple hillslopes in one SLC polygon

• Allocation

– Soil, crop type, tillage system

– Each segment in each landform

Landform

Up

Mid

Low Dep

Methods: wind erosion (WindERI)

• Equation

– Wind Erosion Equation (WEQ)

– AWd = f(I,K,C,L,V)

• Individual factors

– C-, L- and V-factor for the hillslope

– I- and K-factor for each segment

• Adjustments

– Expert knowledge

○ Processes and conditions in Canada

Landform

Up

Mid

Low Dep

TillERI

Erosion Models

WaterERI WindERI

SoilERI

Methods: water erosion (WaterERI)

• Equation

– Universal Soil Loss Equation (USLE)

– ATi = R • K • LS • C • P

• Individual factors --- RUSLE

– R-, C- and P-factor for the hillslope

– K- and LS-factor for each segment

• Adjustments --- RUSLE2

– Interactions between factors

– Soil accumulation rates

– Regression equations

• Intensive test runs in RUSLE2

Landform

Up

Mid

Low Dep

TillERI

Erosion Models

WaterERI WindERI

SoilERI

Methods: tillage erosion (TillERI)

• Equation

– ATi = ET • EL

• Erosivity of tillage ET

– Crop type and tillage system

○ Tillage equipment

○ Number of passes per year

– Field experiment data

• Erodibility of Landform EL

– Slope gradient and slope length

Landform

Up

Mid

Low Dep

TillERI

Erosion Models

WaterERI WindERI

SoilERI

soil loss

soil

accumulation

soil

accumulation

Tillage erosion is the net redistribution (losses and gains) of soil resulting from the

variability in the movement of soil by tillage.

Cropping and tillage systems that employ intensive tillage (frequent, deep, fast)

can cause severe tillage erosion.

20

ET

Methods: integrated soil erosion (SoilERI) • SoilERI model

– ASoil = ATi + AWt + AWd – For each segment in each landform

(hillslope)

• Aggregation

– Area-weighted across

○ Landform

○ Crop type

○ Tillage system

– Value for each segment

○ SLC polygon

○ Province

○ Canada

Landform

Up

Mid

Low Dep

Soil Landscape Canada (SLC) Polygon, 10,000 – 1,000,000 ha

TillERI

Erosion Models

WaterERI WindERI

SoilERI

Province

Canada

Aggregation

Aggregation

Aggregation

ASSESSMENT OF COST

Assessment and Prediction Models:

Classes of Soil Erosion / Degree of Soil Loss:

Results: Average annual soil loss rate for each SLC polygon, landform segment, soil, crop group and tillage system Mapped as most eroding segments (upper and mid slopes) Reported as share (%) of land in each class, rolled up to Province and Canada

Extremely Low / Negligible 0 – 3 t ha-1 yr-1

0 – 6 t ha-1 yr-1

6 – 11 t ha-1 yr-1

11 – 22 t ha-1 yr-1

22 – 33 t ha-1 yr-1

>33 t ha-1 yr-1

} Sustainable

ASSESSMENT OF COST

Distribution of Soil Loss Rates for 1971 and 2011: Wind Erosion

1971

2011 Soil Erosion Risk Classes

* Upper slopes

ASSESSMENT OF COST

Distribution of Soil Loss Rates for 1971 and 2011: Water Erosion

1971


* Upper + Mid slopes

ASSESSMENT OF COST

Distribution of Soil Loss Rates for 1971 and 2011: Tillage Erosion

1971


* Upper slopes

ASSESSMENT OF COST

Distribution of Soil Loss Rates for 1971 and 2011: Soil Erosion

Soil Erosion Risk Classes

1971

2011

* Upper + Mid slopes

ASSESSMENT OF COST

Provincial Overview of Soil Erosion Between 1971 and 2011: Wind, Water and Tillage Erosion, combined as Soil Erosion

Negligible Very Low Low Moderate High Very High

1971 2011 1971 2011 1971 2011 1971 2011 1971 2011 1971 2011

BC 17.1 54.6 22.9 32.4 48.3 9.0 8.6 1.9 0.4 0.5 2.6 1.6

AB 20.9 65.8 32.5 20.3 13.3 10.3 20.2 3.2 7.0 0.3 6.0 0.0

SK 0.0 60.1 19.5 22.7 44.2 15.9 17.2 1.2 15.3 0.0 3.7 0.0

MB 4.2 15.5 37.6 55.7 23.2 19.2 29.5 9.3 5.0 0.3 0.6 0.0

ON 5.5 10.0 16.4 17.8 10.4 14.5 25.0 29.0 18.6 15.4 24.0 13.4

QC 56.8 53.1 16.9 22.5 11.4 11.5 10.6 9.7 2.8 1.6 1.6 1.5

NB 20.6 27.4 21.1 16.0 32.9 33.7 7.9 9.6 7.0 6.5 10.4 6.9

NS 7.2 9.9 15.3 38.9 36.5 33.6 38.3 15.6 1.6 1.6 1.2 0.4

PE 11.5 11.9 7.5 7.9 4.1 3.9 65.7 76.3 11.2 0.0 0.0 0.0

NF 2.7 16.6 11.6 14.5 13.8 6.2 5.9 39.9 25.7 22.8 40.4 0.0

Can 9.4 50.5 24.9 25.6 28.9 14.4 20.0 6.3 11.3 1.7 5.5 1.4

ASSESSMENT OF COST

Provincial Overview of Soil Erosion between 1971 and 2011: Wind, Water and Tillage Erosion, combined as Soil Erosion

Negligible Very Low Low Moderate High Very High M to VH

1971 2011 1971 2011 1971 2011 1971 2011 1971 2011 1971 2011 1971 2011

BC 17.1 54.6 22.9 32.4 48.3 9.0 8.6 1.9 0.4 0.5 2.6 1.6 11.7 4.0

AB 20.9 65.8 32.5 20.3 13.3 10.3 20.2 3.2 7.0 0.3 6.0 0.0 33.3 3.6

SK 0.0 60.1 19.5 22.7 44.2 15.9 17.2 1.2 15.3 0.0 3.7 0.0 36.2 1.2

MB 4.2 15.5 37.6 55.7 23.2 19.2 29.5 9.3 5.0 0.3 0.6 0.0 35.1 9.6

ON 5.5 10.0 16.4 17.8 10.4 14.5 25.0 29.0 18.6 15.4 24.0 13.4 67.7 57.8

QC 56.8 53.1 16.9 22.5 11.4 11.5 10.6 9.7 2.8 1.6 1.6 1.5 14.9 12.9

NB 20.6 27.4 21.1 16.0 32.9 33.7 7.9 9.6 7.0 6.5 10.4 6.9 25.3 22.9

NS 7.2 9.9 15.3 38.9 36.5 33.6 38.3 15.6 1.6 1.6 1.2 0.4 41.1 17.6

PE 11.5 11.9 7.5 7.9 4.1 3.9 65.7 76.3 11.2 0.0 0.0 0.0 76.9 76.3

NF 2.7 16.6 11.6 14.5 13.8 6.2 5.9 39.9 25.7 22.8 40.4 0.0 71.9 62.7

Can 9.4 50.5 24.9 25.6 28.9 14.4 20.0 6.3 11.3 1.7 5.5 1.4 36.8 9.5

ASSESSMENT OF COST

Soil Loss and Yield Loss Relationship:

0

10

20

30

40

50

60

70

80

90

100

0102030405060708090100

Amount of original topsoil remaining (%SOC)

Cro

p y

ield

(%

)

2 x D

T

1 x D

T

Non-linear response

ASSESSMENT OF COST

ASSESSMENT OF COST

1971 2011

Units

Low-Eroding Cropland (N-L)

High-Eroding Cropland (M-VH)

Total Low-Eroding Cropland (N-L)


Total

Cropland Area ha 25,149,351 14,663,025 39,812,376 35,211,104 3,676,329 38,887,434

% 63.2 36.8 100 90.5 9.5 100

63.2 9.5

Soil Loss Rate t ha-1 yr-1 5.9 24.0 3.5 22.7

Relative Crop Yield % 99.5 83 95 40

Crop Yield Loss % 0.5 17 5 60

Annual Soil Loss and Crop Yield Loss in 1971 and 2011

ASSESSMENT OF COST

1971 2011

Units





Total

Cropland Area ha 25,149,351 14,663,025 39,812,376 35,211,104 3,676,329 38,887,434

% 63.2 36.8 100 90.5 9.5 100

63.2 9.5




Degraded Value $2016 13,570,289,11

6 27,326,006,31

6

Non-Degraded Value $2016 14,525,640,87

3 30,429,706,92

1

Lost Value $2016 $0.96 B yr-1 $3.1B yr-1

Cumulative loss up to 1971 in the order of $20-30B

… and Lost Value

ASSESSMENT OF COST

1971 2011

Units





Total

Cropland Area ha 25,149,351 14,663,025 39,812,376 35,211,104 3,676,329 38,887,434

% 63.2 36.8 100 90.5 9.5 100

63.2 9.5




Degraded Value $2016 13,570,289,11

6 27,326,006,31

6

Non-Degraded Value $2016 14,525,640,87

3 30,429,706,92

1

Lost Value $2016 $0.96 B yr-1 $3.1B yr-1

Cumulative loss up to 1971 in the order of $20-30B Cumulative loss from 1971 to 2016 in the order $40-60B

… and Lost Value

ASSESSMENT OF COST

Why has the cost of soil erosion continue to increase since the 1970s and 1980s rather than decrease???

• Even areas where soil erosion is now controlled through soil conservation practices suffer from historical losses of soil.

• Restoring soil productivity on moderately to severely eroded areas is an extremely slow process.

• Cumulative soil losses have pushed yield losses into dramatic declines.

• Although the area of moderately to severely eroded area has decreased in general, a considerable amount of area has not, and on these areas higher value crops are grown.

• The value of crop production has increased. Growing higher value crops on more erodible land.

ASSESSMENT OF COST Average Soil Loss Rate (t ha-1 yr-1) in 2011 by Landform Type

Landform Cropland Area Integrated Tillage Water Wind

(ha) Upper Mid Upper Mid Upper Mid Upper Mid

Hummocky Slight 3,856,887 2.5 1.2 1.6 0.0 0.2 0.5 0.7 0.7

Gentle 4,071,743 7.4 2.0 6.1 0.0 0.5 1.5 0.7 0.5

Moderate 1,076,083 16.7 9.4 13.1 0.0 2.9 9.1 0.7 0.3

Steep 334,848 24.6 20.9 15.2 0.0 8.6 20.6 0.8 0.3 Inclined Slight 791,366 2.6 3.1 0.4 0.0 0.3 0.8 2.0 2.2

Gentle 908,393 2.7 3.5 0.8 0.0 0.9 2.5 1.0 1.0

Moderate 85,668 6.7 7.1 3.0 0.0 1.8 5.2 1.8 2.0

Steep 163,461 12.2 7.2 8.6 0.0 2.3 5.9 1.4 1.5

V Steep 86,253 24.7 11.3 20.5 0.0 3.4 10.5 0.8 0.8 Level Level 4,101,628 4.1 3.6 0.7 0.0 0.8 1.0 2.6 2.6

Rolling Gentle 1,892,458 3.5 5.1 1.6 0.0 1.4 4.8 0.5 0.3

Moderate 771,942 13.5 23.7 2.6 0.0 10.3 23.4 0.6 0.3

Steep 62,303 20.6 29.3 4.8 0.0 15.5 29.2 0.3 0.1 Ridged Slight 214,399 1.1 1.1 0.3 0.0 0.2 0.5 0.6 0.6

Gentle 342,561 3.0 2.9 0.6 0.0 0.6 1.8 1.8 1.1

Moderate 35,068 12.7 22.5 5.4 0.0 7.3 22.5 0.0 0.0 Steep 70,315 7.8 4.3 3.9 0.0 1.4 3.8 2.5 0.5

Undulating Slight 14,569,503 2.2 1.6 0.9 0.0 0.2 0.6 1.0 1.0

Gentle 5,369,683 7.5 6.3 5.1 0.0 1.7 5.8 0.7 0.5

FUTURE RESEARCH

Refinement of the methods:

• Enhanced temporal resolution: Estimate soil loss rates on an annual basis, rather than every five years.

• Enhanced spatial resolution: Application of remotely sensed data and the estimation of soil loss rates on a raster basis rather than a polygon basis.

• More comprehensive relationships between soil loss and loss in crop yield.

• Develops relationships for a range of climate scenarios.

FUTURE RESEARCH

Refinement of the methods:

• Develop highly descriptive tillage profiles to account for variations in tillage equipment associated with climatic regions, soil types, cropping systems and for variations over time.

• Develop highly descriptive cropping profiles to account for variations in tillage equipment associated with climatic regions, soil types, and for variations over time.

• Use probabilities rather than means to describe to better represent likelihoods and uncertainties.

Soil erosion continues to cost Canadian agriculture and the economy substantially.

Although soil conservation efforts have reduced the amount of cropland that is moderately to severely eroded, more needs to be done!

TAKE HOME MESSAGE

Efforts need to be reinvigorated; they need to be smarter; efforts need to be targeted, appropriate to soil and landscapes, climate and cropping systems.

This requires commitment and investment in Discovery and Innovation by all stakeholders.

We need to think more broadly about what tillage is and what conservation tillage is.

There are tillage operations that

are more erosive than the

mouldboard plough

THE WAY FORWARD

We must consider how far soil is moved

during tillage as well as how much crop

residue is left on the soil surface


THE WAY FORWARD

Even seeding operations

cause tillage erosion


THE WAY FORWARD

Even crop management operations

cause tillage erosion


THE WAY FORWARD

A mouldboard plough can be

used as a soil conservation tool

Conservation tillage simply reduces the loss of soil organic carbon and productivity, we must focus on good crop management to increase organic carbon inputs into the soil and increase soil and crop productivity.

THE WAY FORWARD

Soil-Landscape Restoration

Returning eroded soil to the top of

the slope in France in the 1930s

THE WAY FORWARD

More soil research needs to be carried out at the landscape scale.

THE WAY FORWARD

david a. lobb · • adjustments --- rusle2 – interactions between factors – soil accumulation...

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