Soil Ecology

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Soil Ecology Biological Buffering
Understanding the central role of organic matter
in crop production

• P. Larry Phelan
• Ohio State University

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Fundamental tenets

• Everything is connected to everything else

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DDT
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Fundamental tenets

• Everything is connected to everything else

• Agricultural methods generally are designed to
  maintain ecological disequilibrium

• During their entire evolutionary history, plants
  have obtained their nutrients (particularly N)
  through the soil food web

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Plant as portal of above-ground and below-ground
worlds
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• "can't get excited about the difference between
  organic farming and non-organic farming."
  Pesticide residue is a problem, but when it comes
  to fertilizer, "the plant doesn't give a damn"
  whether nitrogen and phosphorous come from manure
  or from a bag of commercial fertilizer
• Pedro Sanchez (Chair, UN Task Force on Hunger)

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European corn borer damage on paired farms Year
1 Year 2
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Corn yield on paired farms Year 1
Year 2


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Plant mineral balance and insects
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Soybeans Grown in Hydroponic Solution
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Soybeans Grown in Hydroponic Solution
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• Does organic farming alter nutritional quality of
  crops?

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Corn nutritional quality
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• Using ecological principles to control weeds

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Weed composition on 3 Ohio paired organic and
conventional farms (2 year avg)
Grasses Broadleaves
Organic farms
Conventional farms
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Soil CN and soybean-weed competition
0 25 50 -Weeds
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• Soil CN effects on soybean-weed competition
• Pigweed

CN 0 CN 50
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Organic yields compared to conventional farming

• Relative Years
• Crop Yield of data
• Corn 94 69
• Soybeans 94 55
• Wheat 97 16
• Tomatoes 100 14
• Source Liebhardt 2001

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Ideal Agriculture

• Maximize productivity (efficient use of land)
• Minimize inputs- energy, chemicals, costs
• Support human systems/communities
• Minimize environmental impact
• Maximize sensory/nutritional quality of product
• Maximize resistance to perturbations
• Maximize resilience to perturbations