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Energetics of Biointensive Vegetable Production. Sara Hendershot Agroecology Internship. Penn State University August 11, 2003. A Quote. - PowerPoint PPT Presentation
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Sara Hendershot
Agroecology Internship
Penn State University
August 11, 2003
“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 it…Perhaps 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
Steve Moore, Harmony Essentials, July 2003
Pest Control
Compost (manure, leaves)
Irrigation
Transportation
Human Labor
Embodied Energy of Tools
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
Activity Factors **
Activity Cal/lb/hr
Category men women
very light .68 .60
light 1.32 1.17
moderate 1.96 1.88
heavy 3.81 3.52
** Duhan, David. One Circle, 1985
Calories = Labor time x Activity Factor x weight
Very light – standing activities…seeding, “pricking out”, etc.
Light – transplanting, harvesting, etc.
Moderate – weeding, U-barring, etc.
Heavy – double digging, strenuous lifting, etc.
Yield (lbs)/bed Calories/lb Calories/bed
159 52 8268
Activities: Seeding, “pricking out”, bed preparation, transplanting, weeding, & harvesting
OUTPUT
LABOR INPUT
Total Labor Time
Calories Expended/bed
108 minutes 293 calories
Activities: Seeding in flats, “pricking out”, bed preparation, transplanting, weeding, & harvesting
Yield (lbs)/bed Calories/lb Calories/bed
50 113 5650
OUTPUT
LABOR INPUT
Total Labor Time
Calories Expended/bed
170 minutes 492 calories
Yield (lbs)/bed Calories/lb
Calories/bed
419 157 65,783
Activities: seeding, bed preparation, transplanting, weeding, & harvesting
OUTPUT
LABOR INPUTTotal Labor Time
Calories Expended/bed
147 minutes 567 calories
Activities: Bed preparation, seeding, weeding, & harvesting
Yield (lbs)/bed Calories/lb Calories/bed
487 156 75,972
Total Labor Time
Calories Expended/bed
127 minutes 459 caloriesOUTPUT
LABOR INPUT
Digging Fork (D handle)
U-Bar (30" W)
Garden Rake
Stirrup Hoe (7")
Trapezoid Hoe (6.5")
4 row seeder
5 prong cultivator
Kaman (hand harvest sythe)
Harvest sheep sheers
6 prong pitch fork
Tools
Weight (Steel)
lbs
Calories/ tool for production
Cal/tool for manufactureand assembly*
Total embodied energy forsteel in each tool
useful life
(years)
Embodied energy per year(Calories)
Digging Fork (D handle) 3.5 23856 3192 27048 25 1082
Garden Rake 3.5 23856 3192 27048 25 1082
Stirrup Hoe (7") 2 13632 1824 15456 10 1546
Trapezoid Hoe (6.5") 0.85 5794 775 6569 5 1314
U-Bar (30" W) 35.5 241968 32376 274344 25 10974
4 row seeder 2.6 17722 2371 20093 25 804
5 prong cultivator 2.1 14314 1915 16229 25 649
Kaman (hand harvest sythe) 1.8 12269 1642 13910 25 556Harvest sheep sheers 0.6 4090 547 4637 25 185
6 prong pitch fork 2.5 17040 2280 19320 25 773
Tool
Weight
(wood) lbs
Calories / tool for
harvest and transport**
Cal/tool for wood drying, workingand assembly
Total embodiedenergy for wood in each tool
useful life
(years)
Wood embodied energy in caloriesper year
Digging Fork (D handle) 1 1100 1320 2420 10 242
Garden Rake 1.25 1375 1650 3025 10 302.5
Stirrup Hoe (7") 1.25 1375 1650 3025 10 302.5
Trapezoid Hoe (6.5") 1.25 1375 1650 3025 10 302.5
4 row seeder 1.5 1650 1980 3630 10 363
5 prong cultivator 1.1 1210 1452 2662 10 266.2
Kaman (hand harvest sythe) 0.25 275 330 605 10 60.5
6 prong pitch fork 1.5 1650 1980 3630 10 363
Digging Fork (D handle) 29,468
U-Bar (30" W) 27,344
4 row seeder 23,723
6 prong pitch fork 22,950
5 prong cultivator 18,891
Stirrup Hoe (7") 18,481
Garden Rake 16,549
Kaman (hand harvest sythe) 14,515
Trapezoid Hoe (6.5") 9,594
Harvest sheep sheers 4,637
Lettuce 145 calories
Broccoli 222 calories
Onions 307 calories
Carrots 240 calories
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
Crop Embodied Energy in Tools
Labor Energy
Total Energy (Cal. Input)
Lettuce 145.42 293.2 439
Broccoli 221.84 491.88 714
Onions 306.59 567.31 874
Carrots 240.26 459.29 700
Crop Total Energy (Cal. Input)
Yield (Calorie Output)
Lettuce 439 8,268
Broccoli 714 5,650
Onions 874 65,783
Carrots 700 75,972
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 ! !
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
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