 Best of the Humusphere
"Best of the Humusphere" are hand-picked essays of interest, announcements, releases, etc. that the managers of the Humusphere believe represent
the core of the issues and discussions surrounding composting and sustainability. Read on to get a taste. If you like it, try other topics.
THE FUNDAMENTALS OF MICROBIAL ECOLOGY OF
INSITU BIOREMEDIATION
Larry J. Forney and James M. Tiedje
NSF Center for Microbial Ecology, Michigan State University
East Lansing, Michigan
BIOAUGMENTATION
There is considerable interest and debate about the efficacy of using
"specialized" microorganisms to enhance biological remediation processes --
so called bioaugmentation. In the typical scenario, pure cultures or
mixtures of microorganisms that are especially adept in degrading specific
classes of contaminants in the laboratory are selected. These specialized
cultures are then used to amend soils or injected into the subsurface with
the intent of increasing the rate of specific metabolic processes. To
perform their intended function, the introduced organisms must survive, grow
and function. However, ecological theory states that only species can occupy
any given niche. So each species introduced into the environment must
compete with the high numbers of different indigenous species present and
must displace one or more of the species present. This is a formidable task
given that each species, by definition, is well-suited and effectively
competes for the niche that it occupies. In many cases, the introduced
species will not be more fit. This is probably true because the indigenous
species for the introduced organisms would have been selected under
conditions that did not mimic the natural environment closely enough. Given
the heterogeneity of soils and the subsurface, and the obvious difficulty of
mimicking natural systems in the laboratory, the "specialized" microorganisms
selected might be used effectively in some but certainly not all environments
(sites). Thus, conclusions as to whether particular "specialized"
microorganisms would be effective in a given environment can only be made
based on empirical, site-specific data. Exceptions to this general principle
would be instances in which none of the indigenous species are able to
efficiently metabolize a contaminant. Under these circumstances, the
introduced species would occupy a 'unfilled' niche. Alternatively, other
perturbations (changes) in the environment might create ecological niches
that could be occupied by introduced species. In sum, it should be
recognized that it is very difficult to predict the efficacy of "specialized"
microorganisms because factors that determine the competitive ability of
microorganisms in the environment are not well understood.
Why Organic Matter?
Organic Matter influences the moisture-holding capacity of the soil, serves
as a supply of nutrients, feeds microorganisms, insects, earthworms, etc.,
and improves soil tilth and structure. The amount of organic matter depends
on temperature, rainfall, aeration and other factors. It tends to be a
characteristic of soil type in a given environment and is not easily changed.
Excessive tillage results in a loss of organic matter. Large additions of
crop residue, compost, mulch, manure, etc. cause only small changes in soil
organic matter. Ideal soils have about 5% organic matter. Excessive
applications of organic matter may tie up available nitrogen. More organic
matter found in mulches would not hurt the garden soil. Compost from the
compost piles is an excellent addition to the gardens, either worked into
the soil or placed on top as a superb organic weed control.
WHAT IS ZEROWASTE?
ZeroWaste is a planning principle for business and citizens in the
21st Century. Waste is inefficiency and businesses must be
encouraged to strive towards environmental efficiency. Just as
businesses don't want to waste time or money, they should be
discouraged from wasting natural resources. Nor should they be
allowed to pass their waste on to consumers, in the form of
"disposable" products and packaging. In a ZeroWaste marketplace,
businesses will create reverse distribution systems to take
products and packaging back into production, rather than
dumping the problem on community incinerators and landfills.
Nature is a ZeroWaste system. Business must learn to be more like
Nature.
Is ZeroWaste necessary?
If all businesses operated as wastefully as do businesses in the
"developed world", we would need THREE PLANET EARTHS to
support them. In our daily lives, we use much more than our fair
share of the earth's resources. As more and more people join the
human family, and all aspire to live the way we live in the
"developed world", the inefficiency we now take for granted will
not be tolerable. ZeroWaste is a discipline we must begin to
practice now. We must learn to eliminate unnecessary waste, in
order to preserve the true quality of life that we aspire to as
human beings -- the quality of life defined by having just enough
of what you want, rather than an abundance of waste -- which no-
one wants.
The North American economic system stands for...
Our economic system is built on the trust we have in the free
market to regulate the production and consumption of goods.
Consumers have the freedom to choose, and their choices guide
the producers in the production of goods. But a free market only
works if the prices of products tells the truth about the costs of
production. For many years, product prices have misled
consumers. Cheap, mass-produced convenience products bear
hidden costs that the consumer never thinks about. Landfills,
incinerators, litter clean-up -- these are all costs that are passed on
to local communities, not paid for by the producers of the
products that become waste. Taxpayer subsidies and tax breaks
that support the squandering of natural resources. Welfare checks
paid to the unemployed -- productive workers who lost their jobs
to automation and mass-production. These environmental and
social costs are hidden subsidies, ways in which the taxpayer
inadvertently encourages businesses to be wasteful and inefficient.
The Solution
A ZeroWaste economy will shift these environmental and social
costs back into the prices of the disposable products and
packaging where they belong, signalling to the consumer that
these are not such bargains after all. In a ZeroWaste economy, the
competitive producer is the one who learns to avoid waste and
invest in jobs that produce high-quality products and services.
The Grassroots Environmental Network is calling for a shift to a
ZeroWaste economy. We want to create jobs, not waste. We want
to end subsidies for waste.
From: Tim Myles t.myles@utoronto.ca
Re: Possible use of termites on spent mushroom substrate or other
agricultural byproducts.
Spent mushroom substrate is likely to be an excellent physical and
nutritional medium for termites. Termites are the main group of
invertebrate animals that digest low-nutrient, lignocellulosic, "brown"
matter. We northern hemisphere biologists have a profound blind spot
when in comes to appreciating the stupendous importance of termites in
the carbon cycle. Termites are the major animal bioconverters of plant
cell wall matter into animal biomass on this planet. I'll just repeat
that: Termites are the major animal bioconverters of plant cell wall
matter into animal biomass on this planet. In performing this they
support a huge percentage of small vertebrate insectivore biodiversity.
One popular misconception about termites is that they eat only wood.
This is true of only the most notorious pests. It is estimated that over
50% of all termite species are humivorous. Entire subfamilies of the
higher termite family Termitidae, such as the Apicotermitinae and
Termitinae are humivourous. Many other termites feed on surface litter,
dry leaves, grass, and even lichens. In arid areas, where animal dung
rapidly becomes too dry for dung flies and dung beetles, termites are
the major decomposers of herbivore dung. In fact, many of the most
abundant termites in arid and semi-arid regions of the world are dung
feeders. This is true in the American Southwest, where several species
of Amitermes, Gnathamitermes, and even Reticulitermes are commonly found
in dung. In fact, I am in the process of describing a new
dung-specialist genus which is found in the American southwest and
Northern Mexico.
Decompiculture, or the culturing of decomposer organisms, is the
inevitable next step in mankind's utilization of natural resources and
ecological integration in the biosphere. Large scale composting is the
first evidence that we are waking up to this ecological imperative.
The most important candidate decomposer organisms are bacteria,
actinomycetes, fungi, earthworms, termites, beetles and flies. Up until
now, these organisms (decomposers) have not been seen as sources of
production. Those of us who study these organisms tend to study the
relatively few that are pests. The majority however are beneficial and
essential cogs in the cycling of nutrients. Now that humankind has
progressed to the point of having numerous large organic waste streams
we must now develop intensive decomposition systems to match our
intensive production systems.
"Termite ranching" or termiticulture inevitably will be much more
important than vermiculture because termites are able to utilize lower
nutrient substrates, wood and humus. Termiticulture could probably be
easily integrated with mushroom production. However termites do not
develop quite as quickly as many other insects thus the start up time
might be several years before the population could consume at the rate
of spent compost delivery. Containment and rearing facilities would
have to take into account their social habits.
Termiticulture may not be feasible out of doors in the temperate part of
the northern hemisphere. The southern tier state of the US would be
adequate for a few genera such as Reticulitermes and Amitermes, but
large scale termiticulture would work best in conjunction with tropical
agriculture, especially wherever there is a large cellulosic waste
component in the food processing. Termite production could also be
integrated with dairy and livestock production as a manure management
system. Matching species to wastes and to stage of waste would be
necessary.
If anyone knows of an innovative tropical agribusiness that would be
interested in putting up the capital for a pilot study, I'd like to hear
from them.
Sincerely,
Tim Myles
++
Dr. Timothy G. Myles, Faculty of Forestry, University of Toronto, 33
Willcocks Street, Toronto, Ontario M5S 3B3, CANADA. t.myles@utoronto.ca
phone: (416) 978-5755
fax: (416) 978-2403
home phone (905) 877-9351
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