Passages Sustainable Food and Farming Systems - PASA

Table 3. Land, labor and energy efficiency of the three LEAFS production systems.
porating all labor inputs for certain crops
for a season as well as yields. The data are
for a mix of crops, some that performed
decently and some that did not do as
well. The beans and tomatoes were intercropped
as were the leeks and onions.
Note that this does not include bed construction
work as that is one-time work,
and we did not add in greenhouse labor
when transplants were used, which at the
high end can be another hour of labor to
produce the 400 transplants needed for a
bed of lettuce. These issues aside, the picture
that emerges is not one of labor inefficiency.
Similarly, the yields per unit of
land, extrapolated to an acre, show that a
gross income of $40,000 per acre is feasible,
and that is reducing value by half
since processing and marketing labor are
not included. Given lower equipment
and input costs, this income goes significantly
farther.
Finally, Table 3 displays how the
human-powered treatment performed as
a whole and in comparison to the animaland
machine-powered treatments. With
a record wet spring followed by a tropical
storm and flooding in the fall, all systems
struggled. As expected, the human system
performed the best in terms of
energy and land efficiency. Energy efficiency
in particular was significantly
higher than in US conventional vegetable
production. Energy return on investment
(EROI) measures the energy produce by
a system relative to the energy needed to
run the system. In modern American
agriculture, EROI values for vegetable
production range from 0.26 (for crops
like spinach) to 1.6 (potatoes) 7 compared
to 5.1 for our system. It is interesting to
note that over a third of the energy inputs
into the human system were in the form
of the energy embodied in seed potatoes
and cover crop seeds with potting soil
being another significant input. When
the system requires inputs derived from
mechanical agriculture, there is a significant
loss of energy efficiency.
Conclusion
We are not alone in collecting quantitative
data to demonstrate the value of
human power in farming. I personally
have derived a lot of inspiration from the
work of John Jeavons and Ecology
Action. While there is a great need for
further research and development of
human powered technologies, the tools
and systems that currently exist are sufficient
to produce vegetables successfully
and efficiently. And is there really anything
so bad about employing a few more
people in the growing of our food I have
the pleasure of working every day with
young adults ready for just such an
opportunity.
References
1. Farm Manager and Research Associate at Green
Mountain College. mulderk@greenmtn.edu,
802-287-2941.
2. Based on data from: Heller and Keoleian (2000)
Life Cycle-Based Sustainability Indicators for
Assessment of the U.S. Food System, The University
of Michigan — Center for Sustainable
Systems, Ann Arbor, MI, 1-60, CSS00-04.
3. Ibid.
4. Pimentel, D., Hepperly, P., Hanson, J., Douds,
D., and R. Seidel. 2005. Environmental, energetic,
and economic comparisons of Organic
and Conventional farming systems. Bioscience
55(7): 573–582.
5. Please note that I am also an oxen teamster and
draft animal enthusiast.
6. Jacke, Dave and Eric Toensmeier, 2005. Edible
Forest Gardens. Chelsea Green Publishing, VT.
7. Pimentel and Pimentel, 2008. Food, Energy and
Society. CRC Press, New York, 2008.
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