Farm Notes
CSA Newsletter
Vol. 10 No. 8
September 7, 2009
Potomac Vegetable Farms
www.potomacvegetablefarms.com
(703) 759-2119 ... Vienna
(540) 882-3885 ... Purcellville
By Rebecca Groisser
Child Labor
of making children work dates back
We believe in child labor at to the very creation of the farm,
Potomac Vegetable Farms- East. It when the four children of Hiu and
sounds bad, but it’s true. While the Tony worked long hours daily, in the
hard physical labor is left up to the fields and out of it. It’s hard to whine
grown men and women, the stand about the 3-5 hours I work daily as a
and CSA can barely function without 17-year-old when I hear the stories
the preteen and teenage crowd. my mother tells me about her seven
Every Monday through Thursday, hour days at 13. It doesn’t mean I
there are multiple little girls running don’t whine, but it at least gives me
around filling the bags and boxes of reason to think. The next large batch
the CSA, and every day, usually two of children was after a long gap
– the children
of the four stand
of Hana and
shifts are filled
Anna, me and
by teenagers. Of
my
cousins.
course, that has
F o r t u n a t e l y,
a downside. On
there are more
September 8, all
of us, so we can
the children and
divide the work
teenagers
go
into
smaller
back to school,
portions.
and everything
However, these
at the stand
little birds have
and CSA gets
to fly away
chaotic
and
sometime. I am
very, very slow- Cherry tomato packers doing their ineffithe
youngest
moving. During cient thing but having fun eating ice.
among the six of
the
summer,
the farm’s system becomes entirely us, and I am a senior in high school
dependent on the children, leaving and leaving for college next year, so
them high and dry once we’ve all Mom has to find another bunch of
dispersed to our respective schools. children to assign shifts and work in
Fortunately, the children like the CSA. That group may be the little
working. Whether it’s because of girls of Blueberry Hill, ranging from
the variety in their jobs, the short 10-13 years old, who have already
shifts, or the pleasant company, it’s begun to work CSA and are learning
the preferred job of many of the the basics of stand work.
Mom has become expert at
children in Blueberry Hill. For those
of us who are related to the family, squeezing the most possible work
it isn’t really a choice. The tradition
continued on page 3
CSA Calendar Update
Sept 14 Final Week Summer Shares,
PVF-East
Sept 21 First Day Autumn Shares,
PVF-East
Oct 11 Open House – PVF-WestOct 14
Oct 18
Oct 21
Nov 9
Tour, wagon ride, potluck
brunch?
Final Day Summer Shares,
PVF-West Farewell to offfarm CSA members
Open House – PVF-East
Tour, wagon ride, potluck
dinner
First Day Autumn Shares,
PVF-West On-farm shares
only
Final Week of CSA, both
farms
We have a few spaces left in the Autumn shares, picking up at the farm at
PVF-East. If you are interested in continuing on, please send a message immediately to Hana.Newcomb@cox.
net. Be warned that the fall shares
are full of leafy greens, much like the
early summer. Also celery, radishes,
turnips, and other possibly unfamiliar
fall treats. By October all the summer vegetables will be a memory – no
beans, tomatoes, squash or corn.
We don’t say this very clearly or
very often, but we don’t really condone splitting shares on a weekly basis. We would recommend alternating weeks with a partner if you don’t
think you can eat a full share. It is
hard to split a butternut squash or to
get a meaningful amount of Chinese
broccoli when you attempt to divide
a green bag (we definitely do not approve of splitting a mini share).
Farm Notes
Are Plants Energy Efficient?
By Gabe Popkin and Neil Zimmerman
We hear a lot about energy these
days, and most people believe that solar
power is going to play a significant role
in our future energy economy. But we
already depend on solar energy, because
the sun provides all the energy that goes
into the food we eat. So we thought it
might be interesting to ask how much of
the sunlight that falls on plants actually
becomes useful food energy.
As you know, each vegetable has
its own nutritional profile. Some, like
tomatoes, contain almost no calories,
whereas others, such as corn, pack a
considerable caloric punch. We thought
it would be more interesting to look at
a high-calorie vegetable, so we chose
corn. We estimated that one corn plant
occupies a square of ground roughly half
a meter on a side, giving it a “footprint”
of .25 square meters. We also know that
the earth is bathed in 340 Watts per
square meter (W/m2) of sunlight energy
(averaged over the surface of the earth)
all the time—almost 8,000 times more
than the total global power demand, if
only we knew how to harness it. You
know how bright a 100-Watt light bulb
is, so imagine 3.4 of these illuminating
every square meter of the planet—that’s
a lot of light!
But how much of this sunlight energy
actually hits our quarter-square meter
corn plant over the course of its lifetime?
It depends a bit on the season, so let’s
say the corn was planted on May 15th
and harvested 90 days later. At our
latitude of about 39 degrees north of the
equator, it would receive an average of
around 14 hours of sunlight per day. But
this sunlight is most direct only at high
noon, so we multiply by a factor of 2/pi
(for reasons you can look up in a calculus
book if you want) to correct for the more
slanted morning and afternoon light. We
also multiply by the cosine of 20 degrees
to correct for the fact that the sun never
quite reaches directly overhead, due to
the fact that we are north of the Tropic
of Cancer (the northernmost latitude
that ever receives direct sunlight). That
gives us an average power of around
50 Watts shining on our corn plant’s
quarter-meter-square
home—one
medium light bulb, rather than 3.4 bright
ones. We make one final, very rough,
approximation—we multiply by ½ to
account for the fact that the corn plant
only occupies its full .25 square meter
allotment when it is fully grown (it takes
Page up much less space when it is young),
and also to take into account that the
plant will receive less sunlight on cloudy
and rainy days.
Even given all that, our plant takes
in a lot of energy—roughly 27,000
Calories, in fact. But we know we don’t
get 27,000 Calories from an ear of corn,
or we couldn’t scarf down two or three
at an afternoon barbecue. In fact, an
ear of sweet corn only has about 90
Calories, so somehow a factor of 300
is lost between the sunlight energy that
lands on the plant and the food energy
we get out of it. Where does it all go?
More than half of it is never absorbed
by the plant at all, because plants only
absorb certain types of light. The sun
emits light waves with a vast range of
wavelengths, from long-wave infrared
to those short-wave UV rays we’re all
afraid of. But chlorophyll absorbs mostly
red and blue light, which represents
only about a third of total solar radiation
at sea level. This means the chlorophyll
in a corn plant can only absorb 9,000 or
so Calories of sunlight in its lifetime, but
still only about 1% of that becomes sugar
that we can eat. What about the rest?
One place that a lot of this energy
goes is the rest of the corn plant. Corn
can be anywhere from five to twelve
feet high or so, and the vast majority of
the non-water mass of the plant comes
from carbon dioxide in the air that
was converted into sugars and starches
through photosynthesis. It turns out that
about half the energy of a corn plant
is in the stalk and leaves, which are
indigestible to us, although scientists
are working on developing enzymes
that can digest corn stalks, in order to
produce biofuels.
Another consideration is that
light is not the only requirement for
photosynthesis. Even on the brightest
day, if the temperature is too cold or if the
local carbon dioxide concentration near
a corn field is too low, photosynthesis
will not proceed as fast as it would
otherwise, and some light will be
“wasted.” Physicist Freeman Dyson
notes that “A field of corn growing in full
sunlight in the middle of the day uses
up all the carbon dioxide within a meter
of the ground in about five minutes. If
the air were not constantly stirred by
convection currents and winds, the corn
would stop growing.”
A third reason that most sunlight
energy doesn’t end up as food is that
the plant itself consumes energy to stay
alive. Even though plants don’t move
around the way animals do, they do
transport minerals and fluids up through
their roots, stalks and leaves; they build
large molecules out of smaller buildings
blocks; and they have immune systems
that fight disease. All of these things take
energy, and all of that energy comes
from the sun.
So plants, it turns out, are pretty darn
inefficient. If we had a worker who was
one-third of 1% efficient, we would fire
him or her on the spot. But before we
fire our plants, we might want to ask,
how efficient are plants relative to other
systems that convert energy from one
form to another? As we noted at the
beginning of this article, we hear a lot
about solar power and how it’s going
to solve all our energy problems. The
good news is that solar panels are a lot
more efficient than plants at converting
sunlight to energy we can use—the
typical panels you can put on your roof
today might be around 20% efficient,
and the fancy ones NASA uses to power
its satellite can reach efficiencies of over
40%. The bad news (beside the fact
that we can’t eat solar panels) is that
these panels are made of expensive
materials like tellurium—one of the
rarest elements on earth—and there is
not enough of these materials to power
the whole world. Scientists are working
on developing new solar cells that can
be made out of common and cheap
elements like silicon. Plants solved
this problem long ago, and build their
molecules out of cheap elements like
continued on page 3
Farm Notes
Canning Workshop
We held our first ever canning
workshop on Monday, August 31.
It was an informal event, of the
Tom Sawyer Fence Painting variety.
About 8 CSA members gathered in
the Common House kitchen and
learned about basic canning equipment, hygiene, blanching and peeling tomatoes, stuffing jars safely, using a pressure canner and also the
water bath method. In about two
hours we canned 40 quarts of whole
peeled and stewed tomatoes without even breaking a sweat. At the
end of the session we used all the
leftover ingredients to make Hana’s
special tomato soup. We were so
engrossed in our work that we forgot
to take pictures, but it was a lovely
scene. We’ll do it again next year,
with more warning.
Page child labor, from page 1
photosynthesis, from page 2
out of every child in her presence.
She makes sure that the task matches
the skill level – for example, if you
happen to be about six years old you
may find yourself filling those plastic
clamshells with cherry tomatoes…
for what seems like hours on end.
To a six year old, this task may seem
monumental (and any adult could
finish it up in about 15 minutes)
so she lets kids take frequent
breaks. She also uses the golf cart
as a carrot on a stick. If you want
to drive the golf cart then you may
find yourself chauffeuring buckets
carbon, nitrogen, oxygen, and metals
found in abundance. Chlorophyll, for
example, has at its center a single atom
of magnesium, which is the eighth most
abundant element in the earth’s crust. So
we may wish to learn a few tricks of the
trade from our old-fashioned, inefficient
plant brethren.
Other energy-conversion systems we
could look at are cars, which convert
about 20% of the energy in gasoline
into motion; the electrical grid, which
converts about 13% of the energy in
coal or uranium into electrical energy at
your outlet (another fraction of which is
wasted by whatever device you power
with it); and cows, which convert about
4 to 5% of the energy they consume into
food we can consume, at least according
to one source looking at feedlot cattle.
With grass-fed cattle we may not care
so much about this number, because we
can’t get a single useful calorie directly
from grass, and cows do us quite a
service by turning it into something both
nutritious and delicious. Just another
great reason to eat grass-fed! It turns out
that cattle in general are quite inefficient
food producers compared to other land
beasts such as pigs and chickens. But we
digress.
Finally, we could ask how efficient
our own bodies are. Unless we happen
to practice cannibalism, we probably we
don’t much care about how much food
energy is stored in the human body. But
we might care how much of the food
energy we consume is available for useful
work. That number seems to be within a
few percentage points of 14%, averaged
over the course of a day, meaning that, if
we have a physically demanding job, we
use about 1 in every 7 Calories we eat
to do work, and the other 6 to maintain
body temperature and other metabolic
activities—staying alive, in other words.
Another way to look at it is that, if we
were to fuel ourselves entirely from corn,
we would only use 1 out of every 2100
Calories of sunlight that falls on a growing
plant to do work. That’s bad enough,
but if we eat a hamburger from a feedlot
cow, it’s even worse—we only use 1 out
of every 42,000 Calories of sunlight that
originally fell on the corn plant the cow
ate! You can think about that next time
you’re out there wiping the sweat from
your brow after a long day of work trying
to set things up just right so those plants
can do their wondrous photosynthetic
thing.
Here is a rough recipe for that
soup, in case you want a pot of the
best summer soup ever.
5 ripe tomatoes, blanched and
peeled
1 small onion, chopped
1 stalk celery with leaves,
chopped
2 T. sugar
½ t. salt
½ t. Italian seasoning
2 T. flour and 1 cup cold water
Combine all the ingredients except flour and water in a heavy pot.
Boil for about 10 minutes. Blend or
use an immersion blender (highly
recommended). Make a paste out
of the flour and water and stir into
the hot soup. Cook a little longer to
thicken, and get rid of the raw flour
taste. When you eat the soup, you
can add milk to make it more like
cream of tomato.
Lydia filling boxes in the CSA cooler.
of rotten tomatoes to the compost
pile – happily. And she pays close
attention to whether your hands
are still moving while you talk – and
moves you away from your friends if
you can’t talk and work at the same
time. She can be just like a teacher
sometimes.
I feel sorry for the adults who will
be left behind to do it all, while we
are sitting in air conditioned comfort
thinking great thoughts and learning
Chinese – but after all, they chose
to be farmers. We just happened
to be born into the family or living
within easy walking distance. Those
farmers by choice will appreciate
us that much more next June when
we meander back down the road
to help make salsa kits, clip onions,
bag beans, sort tomatoes, open
the stand, close the stand, unload
watermelons, count bags…Really,
how do they manage without us?
Farm Notes
Page Notes from the Field
Tomato Report: September 3, 2009
The tomato crop this year peaked
early. I would say that 10 days ago we
had our maximum number of fruits on
the farm. The tomato crop was also rather
late, with the first ripe ones not really
appearing until the first week in August.
That’s a pretty steep curve. Now, I’m not
saying this is your last week, just that the
end is in sight. There has been national
attention around the dreaded Late Blight
on the East Coast tomato crop. We haven’t
seen that blight here yet, but we do have
a resounding and serious case of Early
Blight which is less terrible but still does
damage. Both of these blights are happy
about the coolish wet spring we had.
There isn’t much organic growers can
do – the only advice being to spray with
copper or baking soda etc. Try to imagine
using a hand pump backpack sprayer to
get a spray all over 5000 tomato plants
that are as tall as you and then you’ll see
why I just sit back and take my lumps.
There are very fancy expensive machines
that are designed to spray over such large
plants (some on 9 foot stakes no less!)
but we don’t have one. Enjoy those red
globes of goodness.
By Ellen Polishuk
As for the issue of heirloom tomatoes, I
must weigh in. You have noticed a variety
of shapes, sizes and colors of tomatoes
in your bags this season. The big ugly
strangely shaped ones are “heirloom”
varieties. Basically any heirloom is a
variety or cultivar that has been around a
long time (more than 30 years), and has
been “passed down” from one generation
to the next. In tomato
culture that means that
the variety is therefore an
open-pollinated variety.
That means it can be
propagated by just saving
the seed from any fruit
and planting again the
next year. Whereas a
hybrid tomato is the result of a purposeful
cross pollination between a certain variety
that will be the female (mother) and a
certain different variety that will provide
the pollen (father). The cross is usually
done by human hands, in the field, each
carefully pollinated flower marked with
a tag. Only the marked fruit will yield
a tomato whose seed is the hybrid (like
our favorite Celebrity tomato). In order
to have more seed, the
hand pollinated cross
must be made over and
over again. A gardener
or farmer who attempts
to obtain more Celebrity
tomato seed simply by
harvesting the fruit of a
Celebrity tomato will be
sorely disappointed the
following year. They will
find a very non-uniform
field of tomatoes that are
all different from each
other and from Celebrity
itself. The progeny run
the whole genetic spectrum between
the female and male varieties. This is
why the company who owns the hybrid
Celebrity has an important role to play in
our business. We cannot make the hybrid
Celebrity ourselves because we don’t
know the parents involved.
Back to your bags. I grew too many
heirloom plants this year and so the
stream of oddly colored
and strangely shaped
tomatoes made it into the
CSA bags throughout PVF.
I had intended to only
have enough heirlooms
for the stands and markets.
Why? Heirlooms don’t
travel well. They are quite
delicate: at least half the fruit don’t make
it out of the field. Then another half of the
picked fruit don’t make it into the bags.
That’s a lot of fruit rotting somewhere!
You know whether they lasted on your
counter or not. I hope so! These varieties
are fun to have around but they are hard
on a farmer. They are so much more work
to grow, and the loss is almost intolerable.
We love our hybrids Celebrity, Sweet
Tangerine and Pink Beauty. They are
the firmer, more perfectly shaped fruits
(red, yellow, pink) that you’ve had. We
think they taste pretty dang good. They
are much easier to grow and handle and
successfully deliver to you. We appreciate
what the plant breeders did to improve
the handling qualities of the fruit without
compromising the flavor. So, around here,
we are great users of hybrid seed, and
mere dabblers in the heirlooms. To be
sure, many wonderful heirloom varieties
exist but they are really appropriate for
home gardeners, where the journey from
garden to table is measured in inches and
feet, not miles.