- CARBON STORAGE IN SOIL
The Ultimate No-Regrets Policy?
- A Report to
- GREENING EARTH SOCIETY
- By
- David E. Wojick, Ph.D., P.E.
- November 1, 1999
-
-
There is tremendous
capacity for storage of carbon in soil, both in the United States and
globally. In fact, it is estimated that about 100 billion tons of carbon
that was originally in the soil has been lost due to human activity,
especially through agriculture practices. Most of this carbon could be
returned to the soil, improving the soil in the process. With mankind’s
annual carbon emissions estimated to be just 6 to 8 billion tons, this
signifies huge storage potential.
World soils contain about
3.2 trillion tons of carbon within the top six feet. An estimated 2.5
trillion tons is in the form of soil organic carbon. This is the
organic matter in the soil that makes it fertile. The remaining 0.7
trillion tons is soil inorganic carbon.
These are very large
numbers. In fact the soil carbon pool is 4.2 times the entire atmospheric
pool – and 5.7 times the biotic pool. Thus, even a relatively small
increase in soil carbon taken from the air could provide a significant
reduction in atmospheric carbon. Moreover, since plants feed on carbon
dioxide in the air, the primary way to store carbon in soil is to grow
plants. Improved agriculture is the key to soil storage of carbon. Soil
carbon storage is probably the ultimate "no regrets" climate
policy.
Acknowledgements:
Much of this report’s
technical content is abstracted from The Potential of U.S. Cropland to
Sequester Carbon and Mitigate the Greenhouse Effect by R. Lal, J.M.
Kimble, R.F. Follett, and C.V. Cole [Lewis Publishers, CRC Press, Boca
Raton, FL, 1999]. I have also benefited from attending two symposia:
"Agricultural Practices and Policies for Carbon Sequestration in
Soil" at Ohio State University, July 19–23, 1999, and U.S.
Department of Energy Workshop on Carbon Sequestration Research Needs in
Gaithersburg, MD, September 14–15, 1999.
Many thanks to the
following for useful conversations. I recommend their expertise to anyone
seeking additional information: Rattan Lau at Ohio State University (lal.1@osu.edu),
John Kimble of the USDA National Soil Survey Center (john.kimble@nssc.nrcs.usda.gov),
Earl Kulp of Agroforest Group (ekulp@email.msn.com),
and Fred Palmer, President of Greening Earth Society (fredpalmer@greeningearthsociety.org).
All opinions expressed are my own.
David Wojick
dwojick@shentel.net
Table of Contents
Capacity
for Soil Storage of Carbon
There is tremendous
capacity for storage of carbon in soil, both in the United States and
globally. In fact, it is estimated that about 100 billion tons of carbon
that was originally in the soil has been lost due to human activity,
especially agriculture. Most of this carbon could be returned to the soil,
improving the soil in the process. With mankind’s annual carbon
emissions estimated to be just 6 to 8 billion tons this signifies huge
storage potential.
World soils contain about
3.2 trillion tons of carbon within the top six feet. An estimated 2.5
trillion tons is in the form of soil organic carbon. This is the
organic matter in the soil that makes it fertile. The remaining 0.7
trillion tons is soil inorganic carbon.
These are very large
numbers. In fact the soil carbon pool is 4.2 times the entire atmospheric
pool, and 5.7 times the biotic pool. Thus, even a relatively small
increase in soil carbon, if it is taken from the air, could provide a
significant reduction in atmospheric carbon. Moreover, because plants feed
on carbon dioxide (CO2) in the air, the primary way to store
carbon in soil is to grow plants. Improved agriculture is the key to soil
storage of carbon.
Soil organic matter is
concentrated in the upper 12 inches of the soil. So it is readily depleted
by anthropogenic (human-induced) disturbances such as land use changes and
cultivation. The magnitude of soil carbon depletion is increased by soil
degradation, especially due to erosion. (See figure – Soil Carbon
Storage Replaces Lost Carbon)
Land use changes in
forests, grasslands and wetlands have transformed large areas of the earth
from relatively stable ecosystems to agro-ecosystems under extensive and
intensive use. The introduction of agriculture involves land clearing,
draining, sod breaking, cultivation, replacing perennial vegetation with
annual crops, and fertilizing. These changes have had major impacts on
carbon pools and fluxes around the globe. In the initial phases of these
transformations, major losses of CO2 to the atmosphere occurred
as soil carbon levels adjusted to reduced carbon inputs and increased soil
disturbance.
Intense pressure for
production also has led to serious soil degradation through erosion and
nutrient losses. These trends continue in many areas of the world. In the
U.S. and other industrialized nations with available energy and
technology, agricultural productivity has steadily increased, land
degradation has slowed or reversed, and soil carbon pools have stabilized
or increased. However, soil carbon levels are still well below
pre-agricultural levels.
It is estimated that a
large part (75 to 80%) of the lost carbon can be re-sequestered in the
soils of the earth. Of course the soil carbon storage capacity is finite.
Moreover, ecological factors and management practices limit the rate of
storage. Nevertheless, it is thought possible to achieve this storage over
the next 25 to 50 years. Since most of the original productive capacity of
the earth would be restored in the process, this is indeed the ultimate
"no-regrets" climate policy.
The following table shows
estimates of annual global soil storage of carbon that might be sustained
over the next 25 to 50 years. [Source: Carbon Sequestration – State
of the Science, U.S. Department of Energy, Office of Science and the
Office of Fossil Energy, February 1999 available on-line at http://www.fe.doe.gov/coal_power/sequestration/index.html.
|
(carbon in billion tons
per year) |
| Agricultural lands |
0.85 – 0.90 |
| Biofuel croplands |
0.50 – 0.80 |
| Grasslands |
0.50 |
| Rangelands |
1.20 |
| Forests |
1.00 – 3.00 |
| Deserts and degraded lands |
0.80 – 1.30 |
| Terrestrial sediments |
0.70 – 1.70 |
| Boreal peatlands and other
wetlands |
0.10 – 0.70 |
| Total |
5.65 – 10.1 |
These numbers compare
favorably with total human carbon emissions due to fossil fuel combustion,
which are presently estimated to be six billion tons per year.
One of the key research
questions is how long these rates of carbon storage could be maintained.
Also, there clearly is some maximum capacity for soil storage, but that
capacity is far from certain. Refining such estimates should be one of the
central R&D tasks in any soil-carbon-storage program.
While perhaps surprisingly
large, these relatively high levels of potential carbon storage are not
unreasonable. For example, a five percent increase in total carbon
contained in global terrestrial ecosystems and agro-ecosystems over a
25-year period would store over 100 billion tons of carbon. Storing 100
billion tons over 25 years requires increasing the rate of storage by an
average of only 0.2 percent per year – roughly one half of the amount
estimated above.
The
Science of Soil Carbon Storage
Scientific study of the
potential for soil storage of carbon is relatively recent, because
widespread concerns about climate change have only arisen in the last
decade or so. This is also true with regard to research into practices to
increase soil storage of carbon.
A good "best place to
start" in investigating the science of soil carbon storage is the
recently-published book The Potential of U.S. Cropland to Sequester
Carbon and Mitigate the Greenhouse Effect; by R. Lal, J.M. Kimble, R.F.
Follett, and C.V. Cole [Lewis Publishers, CRC Press, Boca Raton, FL,
1999]. Most of the data referenced in this report comes from the book. CRC
Press also has available many additional titles in this area.
Nevertheless, there is a
large literature on the role of carbon in soil fertility and on ways to
improve or retain the quality of soil for agriculture. The
above-referenced book includes several hundred scholarly references. Among
the principle U.S. soil science journals are:
- Advanced Agronomy
- Crop Science
- Crops and Soils
- Journal of Soil and Water
Conservation
- Journal of Sustainable Agriculture
- Soil & Tillage Research
- Soil Science Society of America
Journal
- Soil Technology
Additionally, every county
in the United States has an agricultural extension agent who is familiar
with this body of science.
Strategies
for Soil Carbon Storage
Soil is an ultimate
storehouse for carbon. Carbon dioxide taken out of the air by
photosynthesis can be stored in soil either as living organisms (biomass
carbon) or in their residue, especially humus. Soil humus is relatively
resistant to biological degradation and has a long storage time, ranging
from decades to centuries. Moreover, the poorer the soil, the greater is
its potential for increased storage. So, the greatest carbon storage
potential is in the countries with the poorest soils.
Numerous practices are
available to increase carbon storage in soil. Many of these improve soil
quality or have direct ecological benefits. Some also decrease carbon
dioxide emissions from the soil. Basic strategies include:
Soil erosion management
- Land conversion and restoration,
including
- Conversion of marginal cropland to
grassland, forest or wetland
- Restoration of degraded lands
- Restricting use of organic soils
- Restoration of wetlands
- Reclamation of mined land and toxic
soils
- Restoration of salt-affected soils
- Intensification of prime
agricultural cropland, including
- Erosion control through conservation
tillage, buffers, conservation reserves, etc.
- Supplemental irrigation
- Soil fertility management
- Improved cropping systems and winter
cover
- Elimination of summer fallow
- Biofuels, including
- Energy crops (including blending
with fossil fuels)
- Biogas from liquid manure
- Soil carbon storage in land for
biofuel
- Improved fertilizer-use efficiency,
including
- Crop rotation and tillage methods
- Nitrification inhibitors
- Mixed farming
- Recycling of organic material
- Biological nitrogen fixation
- Management of rice paddies,
including
- Residue management and tillage
methods
- Water management
- Fertility management
The options directly
related to CO2 emission reduction can be grouped into three
categories: Land conversion and restoration, biofuels that reduce fossil
fuel combustion, and intensification of prime agricultural land.
The basic strategies for
land conversion and restoration are:
Conversion of marginal
agricultural land to non-agricultural restorative uses such as
grassland, forest or wetland;
Restoration of lands that
have been drastically disturbed by processes such as erosion,
salinization, or fertility depletion; and
Restoration of wetlands
and organic soils to their natural vegetation.
These strategies allow some
marginal land to be used to produce biomass for conversion into biofuels.
Such approaches imply
intensification of production from prime agricultural lands through
widespread adoption of best management practices (BMP). A BMP can be both
soil- and ecoregion-specific, and therefore must be specified locally.
However, a BMP typically involves using conservation tillage, also called
"no till" farming. A BMP can also involve crop residue
management, increased fertilizer and water-use efficiencies, increased
crop intensity, and frequently uses cover crops suited to the region and
soil.
Many of the listed
strategies are discussed more fully elsewhere in this report.
Soil
Erosion Management
A large proportion of soil
organic carbon content is concentrated near the soil surface. Therefore it
is highly vulnerable to the processes associated with soil erosion,
particularly oxidation. As a result, accelerated erosion increases
greenhouse gas emissions.
Accelerated erosion is a
severe problem on a large proportion of U.S. farmland, especially cropland
and rangelands. Soil erosion by water is considered severe in Illinois,
Indiana, Kansas, Kentucky, Texas and parts of other states where row crops
are grown. Wind erosion is ranked severe in many arid and semiarid areas
including Arizona, Colorado, New Mexico, Texas and Wyoming.
Like erosion by water,
wind-blown soil often winds up in waterways. As an indicator of the
magnitude of the erosion problem, an estimated 400 million cubic yards of
sediment are dredged each year as part of the maintenance of U.S.
waterways and harbors. Soil erosion has become a major water quality
problem in many parts of the U.S.
Overall it is estimated
that, in the U.S. alone, water erosion removes about 1.5 billion tons of
soil each year. Wind erosion is even worse, removing an estimated 2.5
billion tons. Average erosion is estimated to be about seven tons per
acre, but almost 25 percent of U.S. cropland erodes at a rate three times
that great, or more.
Soil erosion control can be
achieved using a combination of techniques, depending on local conditions.
These include:
Conservation tillage
(basically a technique of not plowing to control weeds and mix the
soil);
Management of crop
residues and cover crops to maintain soil coverage; and Water
management systems, including runoff management.
Land
Conversion and Restoration
Land conversion and
restoration converts marginal agricultural land into ecologically enhanced
land-use systems. Taking fragile lands out of production curtails soil
degradation, sets soil restorative processes in motion, and leads to
significant carbon storage. Under suitable conditions, this storage is
permanent.
The U.S. already has a
policy of land conversion through the Conservation Reserve Program. Lands
eligible for this program include those with highly erodable soil that
cannot be protected with best management practices. Incentives include the
government sharing the cost of converting cropland to alternative uses
such as woodland or cover crops, as well as annual payments. This program
could be expanded and could be exported.
Conservation buffers are
another form of conversion and restoration. Conservation buffers consist
of restored vegetative strips and riparian wetlands used in conjunction
with other recommended practices. In addition to storing carbon, such
strips also can help control flooding and reduce water pollution.
Depending on the characteristics of the biomass, these buffers can be
extremely effective in absorbing water, sediments, and chemicals
transported from agricultural lands. The USDA has a voluntary program to
develop two million miles of conservation buffers by 2002. This program
could be expanded and it could be exported.
Wetland maintenance and
restoration is extremely important for soil carbon storage. This
principally is due to peat accumulation. Wetlands include the swamps, bogs
marshes, mires, fens and other wet ecosystems that cover about six percent
of the earth’s land area. Of these, about 15 percent (or 100 million
acres) are within the U.S.
Peat accumulation is the
result of reduced oxidation of the biomass produced in wetlands. This
effect is so pronounced that wetlands have an important impact on the
global carbon cycle. In fact, while wetlands comprise only six percent of
the land, they hold an estimated 15 percent of the soil organic carbon
pool. They are also extremely important for promoting biodiversity and
improving water quality.
The U.S. has a Wetlands
Reserve Program intended to restore and protect wetlands that have been
converted to agricultural use. The WRP places accepted land areas under
30-year or permanent easements that prohibit drainage. The WRP pays
compensation based on the type of easement and the appraised land value,
up to the full value of the land. This program could be expanded and could
be exported.
Cropland and grazing land
that is irrigated in arid and semiarid regions is prone to salinization
when there is insufficient drainage to carry away salts leached from the
soil. Salinization retards plant growth and inhibits soil carbon storage.
The total area of salt-affected soils in the U.S. is estimated to be 50
million acres. These soils are located primarily in the following water
resource regions: Missouri (44%), Souris-Red-Rainy (16%), California (8%),
Texas-Gulf (7%), Pacific Northwest (5%), Great Basin (4%),
Arkansas-White-Red (4%), and Colorado (4%).
Intensification
of Prime Agricultural Land
Most strategies for
increasing soil storage of carbon imply intensification of production from
prime agricultural lands through widespread adoption of best management
practices (BMP). BMPs are both soil and eco-region specific and therefore
must be specified locally. However, BMPs typically involve conservation
tillage in combination with:
Management of crop
residues and other organic material;
- Water management systems, including:
- Runoff management,
- Drought management through
supplemental irrigation, and Drainage
of seasonally-wet lands to improve aeration and infiltration
capacity;
Improved soil fertility
management practices;.and/or
Improved cropping
systems.
A conservation tillage (CT)
system is defined by the USDA Conservation Tillage Information Center as:
Any tillage and planting system that maintains at least 30 percent of the
soil surface covered by residue after planting to reduce erosion and/or,
where wind erosion is a primary concern, maintains (roughly) at least 1000
pounds per acre of flat, small grain residue (or equivalent) on the
surface during the critical wind erosion period.
In fact, CT is a generic
term that encompasses all tillage systems that reduce loss of soil and
water from cropland, relative to conventional tillage. Conventional
tillage includes plow-based methods, such as successive operations of
plowing (soil turnover with a moldboard plow), mixing (as with a disk
plow), and pulverization (as with a rotovator). CT eliminates one or more
of these operations. CT often involves use of herbicides to control weeds.
Crop residue management is
an integral part of most CT systems. It may include selecting crops that
produce a sufficient amount of residue, as well as sowing cover crops to
provide an effective ground cover. Rather than turning under plant
materials or crop residues following harvest, they are left on the soil
surface to protect the soil. Some important CT variations include no till,
ridge till, minimum till, and sod till. About 37 percent of the cropland
in the U.S. is now managed with a CT system.
Long-term use of a CT
system leads to an increase in soil organic carbon content, as well as
enhancement of soil quality and improvement in soil resilience.
Improving
Fertilizer Usage and Efficiency
Soil fertility status
affects the amount of biomass produced. The soil organic carbon content of
cropland is related directly to the quantity of crop residue returned to
the land and, inversely, to the nitrogen deficit in the soil. Several
experiments have shown that addition of fertilizers on a regular basis for
many years often leads to an increase in soil organic carbon content.
Likewise, pasture
experiments indicate that soil organic content in manured land is
significantly higher than that of unmanured land. In addition to the high
production of below- and above-ground biomass, erosion control is an
important factor in high soil organic carbon content in manured land.
The conservation
effectiveness of manuring and treatments using inorganic fertilizer under
different management systems is revealed in topsoil thickness and the soil’s
clay content.
Producing and transporting
fertilizer requires energy, which typically results in the production of
carbon dioxide due to the combustion of fossil fuel. In fact, about one
third of the energy consumed by farming is in the production and
transportion of fertilizer. As a consequence, improving the efficiency of
fertilizer usage is a key element in any strategy for soil carbon storage.
Efficient usage also reduces runoff and improves water quality.
Vast improvement in the
efficiency of fertilizer use is possible in the U.S. and throughout the
world.
Biofuels
and Soil Carbon Storage
A "biofuel" is
any type of solid, liquid or gaseous fuel that can be produced from
biomass (including its substrates) and can be used as a substitute for
fossil fuel. Biofuels are increasingly recognized as a feasible
alternative to fossil fuel. Not only does a biofuel recycle (as opposed to
creating) atmospheric carbon dioxide, it also stores carbon in the soil.
Sometimes biofuels can be
burned directly. The forest products industry already generates a
significant amount of its electricity by burning its wood waste. In rural
areas many people heat their homes by burning wood. Examples of biofuels
from substrates include ethanol from sugar crops, methanol from woody
crops, and "biodiesel" from oil crops.
Several options can
increase the agricultural production of biofuels. The land area for
biofuel production can be increased by substituting it for other crops.
One can grow biofuel crops on tree plantations as agro-forestry systems.
Biofuel crops can also be grown as an integral component of soil and water
conservation programs, such as in buffer strips.
Idle or marginal land can
be converted to biofuel production. Idle cropland constitutes an estimated
15 percent of total cropland, or about 100 million acres.
Likewise, part of the
above-ground crop residues produced on existing cropland could be used for
biofuel, provided that this is consistent with the maintenance of adequate
levels of groundcover for soil and water conservation.
Cross-cutting
Issues
Bio-Engineering
for Soil Carbon Storage
Since soil carbon storage
is driven by biological processes, the opportunities for bio-engineering
are enormous. Obvious areas of interest include:
- Increased plant carbon content
- Increased root mass development
- Increased crop residue mass or
quality
- Faster growing rates for crops and
forage
- More efficient microbial processes
- Plants better adapted to degraded or
salinized soils.
Moreover, soil carbon
storage involves highly complex systems. Ecological systems and human
technical systems, both of which vary by eco-region, soil type, and many
other factors. Within this complex, the opportunities for subtle but large
improvements through bio-engineering are likely to be numerous. Many, no
doubt, have yet to be thought of and will depend on new research into the
nature of the underlying biological mechanisms and processes.
Social
Changes for Soil Carbon Storage
Changes in land-use
practices – and in land-use itself – may involve social changes.
Globally, among the most
dramatic among such social changes would be abandonment of slash-and-burn
agriculture. Deforestation, biomass burning, and similar methods account
for an estimated 14 percent of anthropogenic carbon dioxide emissions.
Other agricultural practices account for an additional five percent.
Deforestation is occurring
mostly in tropical areas. The total area of tropical forests is about 4.7
billion acres. The annual deforestation rate is estimated to be 0.9
percent, or 42 million acres per year.
Tropical deforestation is
occurring mostly in the Amazon Basin, Central America, the Congo Basin,
and in Sumatra. The resulting greenhouse gas emissions are due to a
combination of biomass burning, biomass decomposition, and mineralization
of soil organic carbon content. In the U.S., deforestation is primarily
confined to slash (the debris left behind) from timbering, land clearing,
and woodcutting. The slash is either burned or left to decompose.
Improved, sustainable
agricultural practices in the tropical Third World will involve
significant social change [see discussion at A Third World Soil Carbon
Storage Program].
In the U.S., the changes
needed to increase soil carbon storage generally could not be
characterized as "social change." Rather they represent shifts
from one practice to another. Among the more dramatic would be a switch to
conservation tillage, not cropping marginal lands, and restoration of
wetlands. While these could be perceived as major changes by the
individuals involved, they are likely to have already been accomplished
locally by others.
Policy Issues
Defining
a "No Regrets" Policy
People who think there is a
low (but nonetheless real) risk of human-induced climate change often
speak of a "no regrets" climate policy. The term is seldom
defined, however. Rather, it is often vaguely alluded to as actions that
are useful even if the climate change threat turns out to be illusory. In
order to confine this study to genuine no regrets soils storage policies,
it is necessary to offer a more precise definition for use. Hence, the
following general derivation and definition.
Suppose there are two
alternative policy options respectively labeled "A" and
"B." Each enjoys positive net benefits apart from the issue of
the threat posed by climate change. Suppose B, however, also enjoys
positive benefits with regard to the threat of climate change.
Suppose, then, that (1)
absent the threat of climate change we would choose option A. But, also
suppose (2) that with the climate-change threat considered we choose
option B. Taking action as described in (1) implies that apart from the
threat of climate change, A is better than B. If we opt for taking the
action described in (2) and the climate-change threat turns out to be
false, we lose benefits, vis-à-vis Action (1). We would
"regret" this loss. Therefore, to avoid the possibility of
regret, the option chosen must have net benefits equal to the ones not
chosen, absent the consideration of the threat of climate change. For
purposes of this report, we will use the following definition of
"no-regrets policy": The choice of one policy option, which has
potential climate change net benefits from among a group of policies that
have equal net benefits, absent the consideration of any purported
climate-change threat.
Of course equality of
benefits is itself a vague concept, probably necessarily so. The actual
effects of any given policy are typically difficult to know in advance (or
after the fact, for that matter). This merely means that the pool of equal
options is likely to be rather large.
But the basic point remains
– a no-regrets climate policy is a choice among policies that are
equally beneficial, absent the consideration of climate change.
Non-climate benefits are a necessary – but not a sufficient –
condition for a no-regrets policy.
Soil carbon storage appears
likely to be a legitimate no-regrets climate policy using this definition.
Increasing carbon storage means improving agricultural land. Moreover,
many of the storage techniques also improve air and water quality, perhaps
even the quality of life itself. There are also numerous ecological
benefits.
Further research and
careful analysis will be necessary to confirm the benefit potential of
soil carbon storage. But the policy certainly appears to be promising.
An
American Soil Carbon Storage Program
Soil storage potential and
the practices needed to increase storage depend on the type of land use.
The primary non-urban uses are cropland, grazing land, woodland, and
wetland. Cropland area in the U.S is around 450 million acres. Grazing
land is about 600 million acres. Forest land is about another 700 million
acres. Wetlands represent about 100 million acres, nearly 30 percent of
which are coastal.
The U.S. already has
several policy initiatives that have the secondary benefit of soil carbon
storage. These include:
- The Conservation Reserve Program to
take highly-erodable and other marginal farm lands out of
production;
- The Wetlands Reserve Program to
restore and protect wetlands that have been converted to
agricultural use; and
A voluntary program to
establish conservation buffers.
Each of these programs can
be expanded on a no-regrets basis. Principally what is lacking is:
- A program to promote use of
conservation tillage systems, as described earlier in this report
(at Intensification of Prime Agricultural Land);
- A program to promote restoration and
intensification of degraded grazing lands; and
- Research and development to support
soil carbon storage initiatives.
A
Third World Soil Carbon Storage Program
The greatest potential for
soil carbon storage lies in restoring degraded soils in tropical regions.
Earl Kulp, a farm system scientist with experience in these regions, has
designed a model program to achieve this goal. The program, called "Greenled
Growth," is interesting in three respects.
First, Greenled Growth is
projected to store from five to seven times as much carbon, annually, as
the U.S. would have to eliminate under terms of the Kyoto Protocol (an
amendment to the UN Framework Convention on Climate Change or "Rio
Treaty" that, if ratified by the U.S. Senate would require the United
States to return its greenhouse gas emissions to seven percent of what
they were in 1990).
Second, the program is
projected to significantly improve the living standards of three billion
of the world's poorest people.
And, third, the Greenled
Growth business plan shows the program paying for itself and earning a
reasonable return-on-investment. In other words, the standard of living
increases are such that the affected people can afford to pay back the
investment with interest – at a rate of 14 percent, as estimated by Kulp.
Kulp's approach is to
analyze the basic eco-regions, with a farm system model for each. Assuming
presently-available technology, he optimizes each farm model for maximum
soil carbon storage. This has the effect of greatly enhancing agricultural
production.
Kulp calls the resulting
farm model "Hi-Biomass Farming." It uses the initial high yields
on basic food crops to diversify land and labor, first into livestock, and
then into high-biomass lumber, forage, and mulch. The mulch is used with
manure to build up the soil and its nutrients.
Kulp's Greenled Growth
model offers compelling evidence that soil carbon storage is the ultimate
no-regrets climate policy.
Soil
Carbon Storage Research and Development Needs.
There are four critical
aspects to be considered in planning a research and development program to
address carbon storage in soil.
Basic Science
What is the potential for a
given strategy to actually work? What are the scientific principles that
govern carbon storage in soil? How much carbon can we actually store?
There has been a great deal
of research on soil science. But because carbon storage, per se, is
a new concept, there are significant unknowns in the basic science.
Measurement and Sensing
How can we measure or
otherwise detect actual carbon storage rates and amounts? There are
well-established laboratory techniques for measuring the carbon content of
soil. But these are too laborious and expensive to be used for
verification purposes. What is lacking are large-scale methods suitable
for program verification. These might be direct measurements, indirect
measurements, remote sensing of land use changes, or a some combination.
As with the science,
because soil storage, per se, is a new concept, the basic
verification tools do not exist. Moreover, the science itself needs
improved large-scale measurement techniques.
Implementation Methods
If a strategy appears
feasible, how should it actually be pursued? Here many engineering issues
arise, likewise issues of cost and benefit estimation methodologies (as
with any large-scale land use program).
Assessment
Where are the best
opportunities to implement various strategies? What are the possible (or
likely) consequences of implementation – not only with regard to soil
carbon storage, but to the local, regional or global ecosystems? While we
have rough answers to these and related questions, there is nothing
approaching a well-formulated decision support system.
