Passages Sustainable Food and Farming Systems - PASA

Human-Powered Ag
continued from page 25
Table 1. Time needed to accomplish two field tasks with human power.
have at least 25 to 30 managed plants
species achieved through intercropping
and undersowing of cover crops, not to
mention rotations. This diversity is key
to many of the ecological services that
make our system efficient.
• Aim for a stable and diverse soil
ecosystem — the Live Web: Being low
input means we need the soil to work
extra hard for us. To enable this, we consciously
develop what Dave Jacke calls
“the live web”; plants feeding the organisms
that protect and feed plants. 6 The
plant diversity mentioned above is essential
to this goal. Similarly, we only half
jokingly refer to our growing beds as
“sacred ground”: thou shalt not step
where thy food is growing.
• Economies of Scale: Human-powered
production for profit is not gardening.
The right tools for a job often require a
certain minimal scale to be economically
efficient. There is certainly a management
tension between being diverse and
mimicking natural systems and achieving
efficient scale, but this aspect is important
to being economically efficient and
there are certainly techniques we do not
use such as deep mulch gardening
because the labor intensity is too high.
• Direct Marketing: One of the big
advantages of operating at a human scale
is the ability to direct market. Low inputs
mean profitability can be attained at a
scale that is very amenable to scale-limited
marketing systems. Combined with
our desire for a high level of diversity, our
vegetable production system is ideally
suited to either a farmers’ market set-up
or a CSA.
• The farmer as ecologist-athlete: Our
system engages both the mind and the
body. Human power requires an expenditure
of human energy, and there is a
distinct need for physical fitness and
exertion while at the same time insuring
our bodies are equipped for the long haul
and work remains enjoyable. Similarly,
the necessary ecological efficiencies this
system needs require the farmer to be an
ecologist of keen observation. Fortunately,
intimate contact with the growing
system is one of the primary strengths of
human power.
Production details of our system will
be provided in the companion article to
this one, to appear in the March/April
issue of this newsletter.
System Performance and Efficiency
Economic, labor and land efficiency
Over the last three years, we have been
conducting scientific as well as informal
research on the efficiency of our humanpowered
vegetable systems. This last year
in particular, as part of the LEAFS project,
we collected detailed data on twenty
100’ production beds as well as comparable
data on our oxen-powered and
machine-powered growing systems. Our
data and observations suggest that our
human-powered systems are labor, land
and energy efficient and can be economically
efficient at the appropriate scale.
Of course the primary concern with
using human power is that there will be a
dramatic increase in the amount of labor.
Our experience and data bear this out,
but not to the extent that might be
feared. In Table 1, we show time data
taken for two of the most difficult tasks
to accomplish relative to machine-powered
agriculture: tillage and cover crop
incorporation. At $15 per hour, these
two tasks cost $15 and $10 respectively,
or under 5% of anticipated gross yield. It
is true that when a bed gets overgrown
with weeds there is a higher price to pay
than is the case with tractor power. It is
also true that we favor cover crops that
either winter kill, such as forage radishes
and oats, or that are tap rooted and easier
to undercut with the wheel hoe (data
shown are for a field pea cover). Such
constraints provide evidence that human
power does require more contemplative
management.
Table 2 shows a broader picture incor-
Table 2. Measured labor and harvests for some human-powered crops in the LEAFS
research project, 2011
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