EarthTalk: The soil beneath our feet is a critical
resource we often take for granted. But I have heard that
there are many threats to soil. What are they and how do
we make things right?
-- J. Lyons, Andover, MA
among the ecology-minded, soil falls well below the radar
of important causes. But the relationship between soil quality
and both environmental and human health is intricately entwined.
From the food we eat and the clothes we wear, to the air
we breathe and water we need to drink, we depend upon the
dirt beneath our feet. Soil nurtures and feeds all life
on Earth, while it under girds our cities, forests, waterways
and crucial agricultural activities. Further, healthy soil
and the plant matter it holds steady act as important “carbon
sinks” that lock vast amounts of carbon up that would
otherwise contribute to global warming.
history, great civilizations prospered where soils were
fertile and fell when soils could no longer sustain rough
treatment. In Mesopotamia, poor land management caused soils
to become degraded, leading to loss of agricultural productivity,
migrations—and ultimately, civilization collapse.
Ancient Greece suffered a similar fate. Many experts also
blame the fall of the great Mayan civilization on soil exhaustion
and erosion, resulting from agricultural practices and clear-cutting
we face many of the same issues: forest loss, over-consumption,
overpopulation and over-worked soils nearing collapse. While
factors such as logging, construction, off-road vehicles,
floods and droughts threaten soil, high use of agricultural
pesticides, fertilizers and other chemicals, as well as
livestock grazing and the “factory farming”
of food animals, are primary culprits.
among threats to soils is damage to or loss of fertile topsoil.
According to the American Society of Agricultural and Biological
Engineers (ASABE), topsoil erosion today reduces productivity
on 29 percent of U.S. cropland and negatively affects 39
percent of rangeland. In West Africa, fertilizer overuse
is causing already acidic soils to become even more so,
making the farming of even native crops difficult. In Sub-Saharan
Africa, declining soil fertility from intensive farming
is a main cause of poverty and hunger.
erosion is equally significant and is becoming more serious
as population growth fuels urban development. Housing and
building projects gouge the soil and strip its vegetation.
Rain then washes the soil away into sewers and then waterways.
This leads not only to water pollution, but the glut of
nutrients the soil carries with it causes “algae blooms”
that use up oxygen and choke out the aquatic life.
farmers in the U.S. and abroad about the damaging effects
of intensive agriculture and over-application of synthetic
fertilizers and pesticides is a good place to start to try
to make things right. Converting more farming over to organic
methods that eschew chemicals altogether is an even better
solution. Supporting local farms also promotes better land
stewardship, as mega farms make heavy use of synthetic fertilizers,
and factory animal farms generate huge amounts of animal
waste, which pollutes surrounding land and soil. And cities
and towns can do their part by supporting low-impact development
and mandating greener design standards.
Scoop on Dirt: Why We Should all Worship the Ground We Walk
I was surprised to learn recently that some cities,
including New York, have outlawed kitchen-sink garbage disposals,
at least in homes. I would have thought these machines were
Earth-friendly. What’s the deal?
-- Maggie Mangan, St. Louis, MO
garbage disposals are not necessarily Earth-friendly in
and of themselves, but they do play a valuable role in grinding
up food scraps into small enough bits for local sewer or
on-site septic systems to handle. In the U.S. overall, about
half of all homes have a garbage disposal in the kitchen.
New York did outlaw the devices for many years, thinking
a ban would alleviate the strain on the city’s aging
sewer system. But a study later conducted in the mid-1990s
found benefits to lifting the ban, including a likely reduction
in rat and cockroach problems and a reduced flow of solid
waste to landfills already bursting at the seams. So in
1997 the Big Apple began allowing the devices again.
But garbage disposals
are not the greenest way to dispose of food waste. According
to Mark Jeantheau of the popular eco-website Grinning Planet,
conscientious consumers interested in returning food-based
nutrients back to the Earth should bypass the garbage disposal
in favor of composting.
waste [in a garbage disposal] does not go back to nature’s
water supply to be gobbled up by fish and other life forms,”
he says. Sewage-treatment and septic systems remove “any
food value the waste might have had.” Indeed, most
modern-day sewer filtration systems utilize chemicals to
rid the outflow of any life forms, beneficial or otherwise.
Plus, grinding food in a garbage disposal uses a lot of
freshwater, which is becoming a more and more precious commodity.
Those on their
own septic systems also might want to minimize their use
of the garbage disposal. According to the U.S. Environmental
Protection Agency (EPA), regular use of garbage disposals
leads to a “more rapid buildup of scum and sludge
layers in the septic tank and increased risk of clogging
in the soil adsorption field due to higher concentrations
of suspended solids in the effluent.” Jeantheau adds
that even if a given septic system is designed to handle
heavier, food-based loads, it still might not be worth the
risk: “There are few homeowner nightmares worse than
having your septic system go belly up.”
may sound like a messy proposition, it doesn’t have
to be. For starters, those doing the dishes should make
sure to dump any and all food waste items into a kitchen-based
composting bin with a lid that seals tight. Many municipalities
now make such bins available to interested residents. A
mesh strainer in the hole in the sink can catch smaller
food scraps and be dumped into the composting bin when the
dishes are done.
When the kitchen-based
compost bin fills up, it can be dumped into a larger composting
bin outside. After four to six months, you should have some
nice compost to add to your garden and jumpstart the health
of your soil. Companies such as The Compost Bin and Clean
Air Gardening offer online sales of a wide variety of quality
compost bins of different shapes and sizes, and provide
a wealth of comparative information for the interested consumer.
Compost Bin; Clean