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