Goals
Co$t of $oil Ero$ion
Rick CruseScott LeeTim SklenarIowa State University
The True Cost of American Food14-17th April 2016Fort Mason
Center San Francisco
What does it cost?
3
What does it cost? And who pays?
On site costs
What does it cost? And who pays?
Off Site costs
What does it cost? We know who will pay.
Global Food Security
1Bakker, M. M., Govers, G. and Rounsevell, M. D. A. 2004. The
Crop Productivity-erosion Relationship: An Analysis Based on
Experimental Work. Catena, 57: 5576What is the relationship between
soil loss and crop yield?yield reductions of approximately 4% per
10 cm (4 inches) of soil loss should be considered realistic.1Where
nutrient deficits are avoided by fertilization, response curves are
generally convex, implying that reductions will become increasingly
severe with further erosion. 1
Boone County. Tom Kaspar, USDA/ARS personal communication.
10 cm erosion starting at 15 inches or 37.5 cm results in 400
kg/ha with yield of 8,946 kg/ha at 15 inches (37.5 cm) top soil
depth. Is 4.5 % reduction for 10 cm loss top soil depth.
Eight bushels lost with 5 inches thinning at 15 -> 10 inch
depth. 12.5 cm & 504 Kg/ha. Or 40 kg/cm or 4 kg/ha/mm. Max
yield ~ 170 bu/A = 10.7 tonnes/ha10 cm erosion -> 400 kg/ha or
3.7% of max.;
8
4.8 T/A
1.6 T/A5.4 T/A
5.4 T/A
8.0 T/A
State Wide Average 5.7 T/A/YROne pound of soil for each pound of
corn produced
Could you identify where greatest water holding capacity exists
and where water for crops would be limited?12
Simplify, Simplify, Simplify, SimplifyAverage 2.2 bu/A yield
loss/inch of topsoil Using Iowa average corn yield 2006-2015 170
bu/A 5% reduction per 4 inches (10 cm)Assume $4.00/Bu corn5.7 tons
soil loss/A cost producer next year $0.35/A
Nutrient Redistribution and LossNutrient value in eroded
topsoil5.7 Tons/AMostly redistributed in fieldSediment Delivery
Ratio = 0.35(5.7 Tons/A) X = 2 Tons/A(2 Tons/A) X ($2.10/Ton1) =
$4.20
1Iowa Learning Farms. 2013. Cost of soil erosion.
http://www.extension.iastate.edu/ilf/sites/www.extension.iastate.edu/files/ilf/Cost_of_Eroded_Soil.pdf
Cumulative cost ($/A)Years1Nutrient loss value $2.10/ton for
exported soil
Cumulative cost ($/A)Years1Nutrient loss value $2.10/ton for
exported soil$30/A/Yr Soil Conservation
Cumulative cost ($/A)Years$30/A/Yr for Soil
Conservation1Nutrient loss value = $28.30/A for exported
topsoil
At 50 years is $4536/A total loss or >$90/A average17
Off Site Costs???$12 - $38 / Acre US cropland1
1Tegtmeier, Erin M; Duffy, Michael, External Costs of
Agricultural Production in the United States, International Journal
of Agricultural Sustainability Vol. 2 no. 1 (2004): 1-20.
Between 2005 and 2014, U.S. taxpayers spent $3 billion in Iowa
through five USDA programs to pay landowners to farm in more
environmentally friendly ways.1Approximately $125/A for 24 million
row crop acresApproximately $12.50/A/Yr
1Rundquist, Soren and Craig Cox. 2016. Fooling ourselves:
voluntary programsfail to clean-up dirty water. Environmental
Working Group. Washington DC.
Conservation Stewardship Program, Conservation Technical
Assistance, Conservation Reserve Program, Conservation Security
Program, Environmental Quality Incentive Program19
Farm Costs ~ $ 4.55/A/YROff Site Damage ~ $25.00/A/YRPublic
Investment ~ $12.50/A/YR $40+/A/YR
Summary
Global Food $ecurity?????Weve had the farm program since the
mid-1930s, and we do have to overproduce to help feed the world.
But we have to take care of this land. If we really have to feed 9
billion people by 2050, were really going to need this soil.1 Seth
Watkins farmer Clarinda, IA.Kezar, Mitch. 2016. Theres no magic
bullet to stop erosion. Commonsense practices help. Successful
Farming. Available on
line.http://www.agriculture.com/content/real-world-conservation
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ConclusionsIndustrial Ag - Soil conservation more expensive than
soil erosion for the farmerSoil conservation is added expenseUnless
farmer owns the land for extended time and erosion rates are
highErosion cost to public is greater than cost to the farmer
