Let's consider the principles
of modern industrial agriculture
and some of the impacts
on the environment.
Today large scale
conventional agriculture
as practices many countries,
including the United States
violates some of the laws
and principles of ecology.
The first thing that agriculture
does, all agriculture does,
is an annual disturbance.
You come in and you plow the
field and you turnover the soil.
You're halting succession.
Naturally plants go
through maybe smaller
to larger and from annuals
to perennials and maybe
from grasses to woody species, to trees.
Agriculture halts that
succession of plants.
In large industrial
agriculture, there's typically
the removal of organic
material that could
be allowed to decompose and
return nutrients to the soil.
There's typically the removal of
natural insects and other organisms
because you're applying
pesticides typically.
A great deal of energy goes into
growing, irrigating, fertilizing,
harvesting, transporting,
processing, and preparing food.
That's not only happening
on a commercial large scale
agricultural farm, but there is a lot
of that going on and possibly more of it
because the large scale farm is
using pesticides, fertilizers,
that are coming from fossil fuels.
When considering any kind
of agricultural method
it's valuable to know
the energy subsidy, which
is the energy that is required
for each calorie of food produced.
So for example, when
growing corn there might
be four calories of fossil fuel energy
expended to yield one calorie of corn.
The energy subsidy for conventionally
grown corn, we say is four calories.
That's for the tractors
and the irrigation
and the fertilizer and the
pesticide and all the energy
inputs, all the fossil fuel energy
inputs that go into growing that corn.
Small scale agriculture
has a lower energy subsidy
than industrial large scale agriculture.
Beef has a higher energy
subsidy than chicken or pork.
Meat and poultry have
a higher energy subsidy
than plant based crops like
lettuce or tomatoes for example.
So each different food
item and the way it's
grown all factor into
a given energy subsidy.
The average American
diet in the United States
requires 10 calories of energy
for every calorie consumed.
By contrast a hunter-gatherer
diet may require
less than one calorie of energy subsidy.
Some energy intensive costs to
agriculture that are most notable
are as we said the
production of fertilizers,
which require large
amounts of fossil fuel.
Running tractors on any kind
of farm involves fossil fuel
and contributes to the energy
subsidy of those food items.
Shipping food especially if
it's transported by airplane,
especially if the food must be
kept refrigerated or frozen,
all the shipping costs
add to the energy subsidy.
Pumping water if there's
a lot of irrigation
that's going to involve
using electricity.
Coming from the grid, it's
probably coming from fossil fuels.
Irrigation, if not done properly,
can lead to water logging.
That occurs when soils
remain wet or underwater
for prolonged periods of time.
Water logging impairs root growth,
because roots can't get enough oxygen.
Water logging also leads to
anaerobic respiration in the soil
and the release of
potent greenhouse gases,
both nitrous oxide and
methane, potentially released
from organic waterlogged soils.
Another thing that happens with
irrigation is salinization.
Salinization occurs when small amounts
of salts in the irrigation water
become highly concentrated on the
soil surfaces through evaporation.
So the water evaporates as pure
H20 and the salts get left behind.
And at some point those salts can
reach toxic levels in the soils
and impede plant growth.
Intensive irrigation can also
reduce the availability of water
for other purposes.
Say you need it for drinking,
or for industrial purposes
or whatever else it might be.
It also takes water out
of the ecosystem and so
your ecosystem services
may not be delivered
as well or in as great
abundance if you're
diverting a lot of water for irrigation.
In commercial agriculture,
typically uses monocultures.
Large, even-spaced rows with one species
that leads to minimal biodiversity.
A biodiversity of one,
that's quite small.
It has improved
agricultural productivity.
It allows large areas of
land to be planted, treated,
and harvested all at the same time.
But monocropping makes crops more
vulnerable to pest invasions.
A large expanse of the
single crop species
represents a vast food supply for a
pest that specializes on that one crop.
So monocropping makes plants more
vulnerable to insects and other pests.
Modern industrial agriculture also
contributes to habitat fragmentation.
You have large areas
of land where you maybe
are putting in roads and
access points around the edges.
And that allows certain
species to enter those areas
and it maybe excludes other species.
Monocropping can lead
to more soil erosion
than intercropping mixing
different species of crops.
Since a large area is harvested all at
the same time, a large expanse of soil
will remain uncovered and unprotected
for an extended period of time.
Which could lead to water or
wind corrosion of the soil.
Mechanization is something going
on in a great amount in large scale
industrial agriculture.
Fields must be plowed,
planted, irrigated, weeded,
protected from pests, harvested and
then prepared for the next season.
Most of this work is
less costly when it's
done with machines rather
than with human labor.
So mechanization allows for large
farms to be more economically
profitable than small farms.
But not necessarily is this better
off for the natural environment.
