So where does all this energy come from? We all
know the answer - mostly oil, some natural gas and electricity (mostly
from coal). The
term sustainable means lasting well into the future. How long will
the oil last?
In the March issue of Scientific American two oil
industry analysts estimate that the current proved reserves of conventional
oil could last 43 years. That is the good news. The bad
news is that world oil production should peak and then begin its slow
decline sooner than most people think, within 10 years. This is because
the last barrel of oil extracted from a well is much harder to get
than the first barrel. After
the peak is reached, oil will become harder to pump and therefore
become more expensive.
Proved world-wide reserves of natural gas could
last 100 years at current consumption rates. But as oil starts
to decline, natural gas use will increase so it will be used up faster.
As with oil, gas prices will rise when it becomes harder to extract.
Estimates of how long these fuels will last are
always changing. But
the fact remains that fossil fuels are non-renewable and therefore not
a sustainable energy supply.
Another factor in determining sustainability is
it ask what harm is being done to the environment and health of the
people by using this resource. Fossil fuels certainly fail this
test. The extraction, processing and burning of these fuels is the
largest single cause of environmental degradation - oil spills, toxic
waste, urban smog, acid rain and ultimately global climate change.
Seven billion tons of carbon dioxide are emitted
a year. The world's
top climate scientists predict global temperatures will rise 2-6
degrees F in the next century causing sea levels to rise 1-3 feet, disrupting
growing seasons, causing worse storms, heat waves, floods and spread
Where will energy come from and how will it be
used in a sustainable agriculture system? The first step is energy
tillage is one way. As above figures show, chisel plowing used
almost half the fuel of plowing. Using less fertilizer and pesticides
also reduces energy use. Organic fertilizers generally take less
energy to produce than their chemical equivalents.
Local marketing where ever possible would greatly reduce the huge amount
of energy now used to transport agricultural products.
Rotational grazing to produce livestock offers
a large energy savings over conventional methods. Just compare
the amount of energy to run an electric fence to the amount to produce
and transport all the hay and grain to feed those animals in confinement.
In addition to more energy efficient practices, other sources of energy
must replace fossil fuel use.
An over-looked source of energy in agriculture
to human power. Fossil
fuel energy has replaced human energy in every facet of modern life,
including farming. Smaller, more intensive farms employ more people
and use less energy.
On my farm I have about one acre in vegetable gardens.
A little less than a quarter of that is raised beds which I work entirely
by hand - no tiller. The rest I work with a tractor using conventional
tillage. Last year that quarter acre produced 42% of my gross sales.
Human labor may work on small intensive farms but not for crops such
as grain and forage that require large acreage.
A century ago animals powered agriculture. Using animal
power looks sustainable from the criteria of how long will it last and
what environmental damage is done. But there is also the element
of extent - how widely can we use this practice and still produce enough
food to feed a growing population? Whether using rotational grazing
or conventional methods, feeding draft animals takes a lot of land. (I
have 2 horses to feed on my farm.)
If animal power were to replace a significant part
of the tractor power, how much land would be used to feed those animals? Would
there be enough to feed the almost 6 billion and growing human population?
I don't have any answer here, but am sure there is a limit to the extent
draft animals could be used.
What alternative sources of energy are there? Biogas
is one. Methane can be made from manure, and the residue left over is
still good fertilizer. It
can also be made from garbage. All our landfills should be producing
Ethanol is another. In Brazil ethanol is made from
sugar cane and in the U.S. it is made from corn. But these are annual
crops raised on prime farmland so it puts energy production into direct
competition with food production. Also, counting all the energy
to grow the crop and produce the ethanol, there is more energy put in
than you get out.
A better system would be to make ethanol from wastes
or perennial crops grown on marginal land. The practicality of
this has not yet been demonstrated, but it holds promise.
The ultimate source of sustainable energy for agriculture,
as well many other uses, is solar generated hydrogen. But who
knows when it will be available, or even it if could be practically
used in agriculture?
So is the way I farm sustainable? No. Why not? Lots
of good excusses - too busy trying to make a living, too set in my ways. I
am raising the question what is sustainable just to get people to start
thinking about it. But it is much easier to ask a question than
put in practice the answer.