The Cost of Soil Erosion. Rick Cruse Scott Lee Iowa State University

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1 The Cost of Soil Erosion Rick Cruse Scott Lee Iowa State University

2 Different days, different locations, 2014

3 IOWA 2013

4 Soil erosion? Is economically viable Is not economically viable Will always occur on farmed land at unsustainable levels Cannot be stopped Has greater off site costs than on site costs

5 How does soil erosion impact $$$ Crop yield Soil fertility Water quality Flooding Loss of upland water storage Reduction in flood plain storage Reduction in reservoir storage

6 What is value of 1Ton topsoil saved? $0.50 $1.00 $10.00 $25.00 $50.00 $100.00

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8 Rathbun Lake Watershed Project* 354,000 acre watershed $24 million invested since 2006 Sediment loss reduced > 41,000 Ton/yr P loss reduced > 175,000 lbs *Des Moines Register, June 15, Jason Clayworth.

9 Rathbun Lake Watershed Project Since 2006 cost is ~ $83/ton soil $237/lb P

10 Goal Identify erosion impact on crop yield & $$$

11 Identify erosion impact on yield HOW?

12 S. Jagadamma, R. Lal, and B.K. Rimal Effect of topsoil depth and soil amendments on corn yield and properties of two Alfisols in central Ohio. J. Soil and Water Cons. 64:70-80.

13 Approach Identify topsoil depth impact on yield Identify change of topsoil depth since agriculture began in Iowa With the Iowa Daily Erosion Project v.2 identify change in topsoil depth that is occurring real time (actually close to real).

14 What is past erosion costing us? Erosion has caused what change in topsoil depth? What is crop yield response to topsoil depth? Over what area are crops being produced? What is the market value of the commodity?

15 How much soil has eroded?

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17 How much soil has eroded Use average NRI estimate since 1982 (5.5 T/A/YR) Assume erosion rate for last 150 years Sheet and rill only Adjusted for ephemeral gullies 150 yrs farming 6.8 inches soil

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19 What is crop yield response to topsoil depth?

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21 A horizon thinning 6.8 inches -> 5 & 11 bu/a

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23 Yield (Bu/A (Bu/A) Depth (in) Blackhawk County. 6.8 inch soil thinning 19 bu/a

24 Normalized Yield 1.00 TSD vs. Normalized Yield: Corn TSD (in) Marshall County. 6.8 inches soil thinning -> 18 bu/a

25 Mitchell County. 6.8 inches topsoil loss 18 bu corn/a

26 % Max Yield 1.00 Corn Yield vs Topsoil Depth TSD (in) 2008 (24 in) 2010 (30 in) 2012 (14 in) Linear (2008) Linear (2010) Linear (2012) Mitchell County. 6.8 inches topsoil loss 29 bu corn/a in 2012 David B. Lobell, Michael J. Roberts, Wolfram Schlenker, Noah Braun, Bertis B. Little, Roderick M. Rejesus, and Graeme L. Hammer Greater sensitivity to drought accompanies maize yield increase in the U.S. Midwest. Science. 344:

27 From where does $1 Billion come? Average soil loss 6.8 inches Average corn yield loss 10 bu/a Assume 20 million acres of corn Assume market of $5.00/bu 10 bu/a X 20 million A X $5.00/bu = $1 Billion

28 How much does erosion cost $/A/Yr? $1 billion 150 years 20 million acres $0.33/A/Yr

29 What is value of 1Ton topsoil saved? $0.50 $1.00 $10.00 $25.00 $50.00 $100.00

30 Rathbun Lake Watershed Project Since 2006 cost is ~ $83/ton soil $237/lb P

31 Annual cost impact are constant. Each year lose permanently $1.00 production Production loss is cumulative Year 1 erosion occurs Year 2 cost $1.00 from year 1 erosion = $1.00 Year 3 cost $1.00 from yr 1 + $1.00 = $2.00 Year 4 cost $1.00 from each previous year = $3.00 Year 5 cost $4.00 Year 6 cost $5.00

32 Cumulative Cost Increases with Time Year 1 - $0.00 = $0.00 Year 2 - $1.00 (yr 1) = $1.00 Year 3 - $1.00 (yr 2) + $2.00 (yr 3)= $3.00 Year 4 - $1.00 (yr 1) + $2.00 (yr 3) + $3.00 = $6.00 Year 5 - $ $4.00 = $10.00 Year 6 - $ $5.00 = $15.00 Year 7 - $ $6.00 = $21.00

33 Cost or Return on Investment $1, $1, $ $ $ $ Cumulative loss Cumulative Conservation Investment $ Years of Farming Land Conservation investment of $40/A/YR; Soil loss = $1.00/T

34 Cost or Return on Investment $3, Soil Value $0.50/Ton $3, $2, $2, $1, $1, $ $ Years Cumulative loss Cumulative Conservation Investment

35 Summary Soil off site impacts seem economically more important than on site yield economic impacts Return on conservation investment takes TIME! Soil conservation expenses for renters seldom will be recovered

36 Challenges we face What evidence exists that we are on a functionally sustainable path? If not on a sustainable path do we have a vision of what that path is? Do we have the political will to address the causes rather than the symptoms of our current problems?

37 Ag Realities Agriculture if morphing to Agribusiness Fewer farmers control more Enterprise size is increasing Culture is multidimensional, business is less so Farming is very competitive Successful farmers make money

38 Ag Realities Voluntary conservation approaches work best when incentives and benefits are aligned Majority of harvested land is rented Conservation incentives and benefits are not well aligned Markets are farmed, not the land

39 Ag Realities Very strong ag and industry lobby Rationally not aligned with conservation goals Aligned with $$$ for individual industry Major policy elements not well aligned with soil conservation and water quality Soil erosion science is weak

40 Frequency Ag Realities Conservation Exploitation

41 What s New Increased watershed focus Industry recognition of sustainability issues Food industry talking the talk will they walk the walk? Farmers vocalizing the R word Increased emphasis on cover crops

42 What s not new Specialization Loss of cultural based management skills and increasing reliance on technology Growth in size of operations and equipment

43 What s not new Government policy in conflict with conservation Degradation of soil and water resources

44 Elements of a fix Goal and a Plan Commitment to those goals Agriculture and agribusiness are different and must be treated as such Policies That do not put conservation committed farmers at a competitive disadvantage Address the problem, not the symptom Exploitation at expense of conservation