Energetics of

1
Energetics of Biointensive Vegetable Production
Sara Hendershot Agroecology Internship
Penn State University August 11, 2003
2
A Quote...
And energy is superhuman in the sense that
humans cannot create it. They can only refine or
convert it. And they are bound to it by one of
the paradoxes of religion. They cannot have it
except by losing it they cannot use it except by
destroying itPerhaps from an objective point
of view it is incorrect to say that we can
destroy energy. We can only change it. Or we
can destroy it also by wasting it that is, by
changing it into a form in which we cannot use it
again. Wendell Berry, The Use
of Energy, The Unsettling of America, 1977
3
Energy Flow Chart
Steve Moore, Harmony Essentials, July 2003
4
Energy Quantified

• Human Labor
• Embodied Energy of Tools

Not quantified

• Pest Control
• Compost (manure, leaves)
• Irrigation
• Transportation

5
Materials and Methods

• All data is presented based on 100 square feet
  beds (20 X 5)
• Study focuses on 4 crops Onions, lettuce,
  broccoli, and carrots
• Time in labor was recorded per crop over past 10
  weeks
• Tool usage was also logged for each crop

6
Calorie Calculations
Calories Labor time x Activity Factor x weight
Very light standing activitiesseeding,
pricking out, etc. Light transplanting,
harvesting, etc. Moderate weeding, U-barring,
etc. Heavy double digging, strenuous lifting,
etc.
Duhan, David. One Circle, 1985
7
Lettuce
Activities Seeding, pricking out, bed
preparation, transplanting, weeding, harvesting
LABOR INPUT
OUTPUT
8
Broccoli
Activities Seeding in flats, pricking out,
bed preparation, transplanting, weeding,
harvesting
LABOR INPUT
OUTPUT
9
Onions
Activities seeding, bed preparation,
transplanting, weeding, harvesting
LABOR INPUT
OUTPUT
10
Carrots
Activities Bed preparation, seeding, weeding,
harvesting
LABOR INPUT
OUTPUT
11
The Tools
12
Embodied Energy of Steel in Tools
13
Embodied Energy of Wood in Tools
14
Total Embodied Energy of Tools Per Year in
Calories
15
Embodied Energy of Tools per Crop Bed
Calculation Sum energy of tools x bed crop
Energy of tools 52 weeks
weeks needed for crop / yr Energy of
tools / 313 beds Energy of tools per
crop bed
16
Results
17
Results
18
Which means...

• Leaf/Fruit crops yielded an average of 12x more
  energy than was invested

• Root crops yielded an average of 92x more
  energy than was invested ! !

19
For Future Research...

• investigate energetics of compost, irrigation,
  pest control, and transportation
• accurate comparison of conventional and
  mechanized organic farming to biointensive
  practices
• effects of labor requirements based on farm
  size

20
References
Duhon, David. Solving the Diet One Circle,
Ecology Action, Willets, CA 1985,
pp25-26. Jeavons, John. Master Charts, How to
Grow More Vegetables. Ten Speed Press, Berkeley
CA, 2002, pp 88-92. Miller, G. Tyler. Living in
our Environment, 8th Ed. Wadsworth Publishing,
Belmont CA, 1994, p 365. Moore, Steve. Personal
Correspondence, June-August 2003. Pimentel,
David, Energy Inputs in Production Agriculture
in Fluck, Richard D., Ed, Energy in Farm
Production, Elsevier Press, New York 1992, p 24.
Pimentel, David. Personal Correspondence via
email, July-August 2003