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Soil:
Oceanic City platforms will
not naturally have soil on them. Soil would either have to be imported from
land or, which would be more feasible and sustainable, made from ocean
resources. The practicality of making soil is astoundingly simple. Due to the
abundance on land people rarely think about soil and where to get it. With the
exceptions of desert locations where top soil and fertile soil is a problem.
Soil is made up of a mixture
of organic material and minerals. The organic matter comes from dead plants and
many of the minerals come from the rocks underground. These rocks, which are
part of the lithosphere, are referred to as bedrock. Because the plants grow on
top of the soil and the rocks are found underground, soil is made up of layers.
(See Soil Illustration 1)
The type of soil that forms in a region will depend upon the climate, the bedrock underground, and the plants growing there. In deciduous forests the soil may be deep, rich, and dark brown in colour. In sandy areas the soil will be dry with a dusty grey colour. In tropical regions the soil is often very deep and bright red.
For Oceanic Platforms we
will build our own soil. From the illustration above we need at least three
components:
Bed rock – which will be the
concrete structure of the platforms themselves and the concrete roofs of
buildings on top of the platform.
Rock partials of varying
size from gravel to sand, readily had through dredging of the floor of the
ocean, however it can be grown either in the form of corals or in the Bio-Rock
process.
Humus or Organic material.
This last can come from many sources and it can be demonstrated that when it
comes to plants organic material is made from CO2 and sunlight. One plant
could, in theory, produce organic material for two plants, those too eventually
would produce material for 4 plants and so on until a biome is created.
Mariculture, or the growing
and harvesting of kelp and algae and plankton will provide Oceanic City with an
unlimited source of organic material, in broad general terms the marine plants
will take the building blocks of organic material from the ocean and deposit it
in their fibers, the act of harvesting and composting will reduce those fibers
to organic material for soil.
The initial platforms will
have to import a limited amount of soil to get started, however with a small
amount of soil and with a little work and planning soil could be grown out of
the sea with no dredging necessary.
Amount of soil needed for
plants:
Most plants require only 6
inches of soil. As is demonstrated in houseplants around the world, a small
vessel (pot) of soil can sustain a plant for years. With regular addition of
fertilizers and water a plant survives in its little home with no problem.
Farmers know that only the top 6 to 7 inches of soil is actually used by their
crops; the rest of the soil is used for drainage and a foundation upon which
everything rests on the earth. Oceanic City would therefore only require 6-7
inches of soil, plus some drainage, the foundation upon which it all rests are
the platforms themselves floating upon the waters of the deep blue sea.
Trees: Tree Root Systems
Tree roots serve a variety
of functions for the tree. Roots absorb and transfer moisture and minerals as
well as provide support for the above ground portion. There are two basic types
of roots, woody and non-woody.
Non-woody
roots are found mostly in the upper few inches of soil. The primary function of
these roots is to absorb water and nutrients. These are often called feeder
roots. In addition, some trees, particularly deciduous trees such as ash, have
extensions called root hairs that increase root surface area and increase
nutrient and water uptake. Evergreen trees such as pine may not have root hairs
but possess mychorrhizae. Mychorrhizae are fungi that live on and in the feeder
roots. This fungus do not cause any harm to the tree. In fact, for some species
it is very beneficial for the tree to have this fungal association.
Woody
roots are large lateral roots that form near the base of root and stem (the
root collar). The primary purpose of these roots is support and anchorage for
the tree. They also provide water and mineral transport as well as carbohydrate
storage. These roots are distinct for each tree species and provide the
framework for the tree's root system. The general direction for this framework
is radial and horizontal. These roots are located 8 to 12 inches below the soil
surface and can extend 4 to 7 times the drip line of the tree. These roots are
perennial and show annual growth rings, which is why many tree roots eventually
become exposed.
In
drier soils, some tree species will form "striker roots" at intervals
along the framework system. These roots grow vertically downward until they
encounter an obstacle or soil with insufficient oxygen for growth. They will
often branch and form a second layer of roots deeper in the soil. These roots
function as water and food storage areas for the tree.
Another
type of root is the adventitious root. These roots will often form
spontaneously at the root collar from large woody roots. Although it is not
known exactly what causes their formation, they usually develop as a result of
injury.
There
are many misconceptions about root growth in trees. Horizontal root spread is
one of the more important. It is often said that the majority of feeder roots
are concentrated at the drip line of the tree. Roots extend to that distance
and much farther. Studies have shown root spread to be 4 to 7 times the drip
line distance (radius) of the tree. This is an important fact to remember when
applying herbicides, fertilizers, insecticides, and other soil treatments
around trees. Careful consideration can prevent serious injury to your trees.
Another
misconception is root depth. Roots will grow wherever the environment is
favorable. They require water, oxygen, minerals, support, and warmth. These
requirements are usually found in the upper few feet of soil. Roots rarely grow
below four feet although there are numerous cases stating the opposite. The
major portion of a tree's root system is in the top few inches of soil. This
makes it easier to understand why trees can be easily uplifted during
windstorms or other soil disturbances.
The
main point to take home from this is that tree roots are extensive and are
located in the upper few inches of soil. Broadcast fertilizers are very much
available to the tree roots as are herbicides and other chemicals. Soil
compaction is one of the biggest problems a tree root can have. Water and
oxygen become unavailable when the pore spaces are closed. Avoid large grade changes
during construction, both filling and removal. Avoid the use of plastic as
mulch or under mulches, use weed barriers that breathe. Many tree problems are
accidental by understanding more about the tree root system these problems can
be avoided.
This article originally
appeared in the April 1, 1992 issue, pp. 1992 issue, pp. 43-44.
From the article above we
get a good idea of just how deep soil must be for trees, 48 inches (4 feet) is
a great depth. The determining factor is not depth but the radius of the canopy
(leafy branches), which determines “drip line”.
From Japan comes the art of
bonsai where varieties of tree are kept smaller and require a few inches of
soil. Usually done in a shallow tray-like pot, the art is not lost and
demonstrates that trees can be grown in very little soil.
From the above we get a good
idea of how Oceanic Platforms should design its soil.
For our bedrock we will have
the platform itself. The surface of the platform or in the case of residential
roofs will be reinforced concrete (later reinforced bio-rock) of approximately
12 inches of thickness. On top of that would be a water barrier to prevent
leaking of ground water through the concrete to affect the space beneath. There
are various epoxies and products on the market that are latex (water) based,
plastics can be made from plant materials and could be formed as bed liners.
There are many options on how to seal the concrete.
On top of our liner would be
aggregate material. Although this may sound like a special material it is
simply gravel. The ocean floor is riddled with gravel in some areas dredging of
seafloor for sand, rock and gravel already takes place around the world with
little impact on the environment. Other alternatives would be harvested coral
(Grown on platforms partially submerged to make shallow water environments),
even bio-rock could be grown and broken up for this purposes.
Throughout the gravel bed
drainage pipes would be used. The pipes would simply be pipes with holes
allowing the flow of water into the pipe to where it could be drained out into
tanks for reuse.
On top of that layer would
be a sand and pebble layer, on top of that a layer of soil composed of sand and
organic materials composted and semi-composted. Again pebbles even sand could
be dredged or grown or come from a renewable resource.
Depending on its usage, soil
and layer depths would range from 3 to 6 inches. In the case of plants the
depth would be around 12” total, allowing 4-5 inches of gravel and drainpipe,
with 1-2 inches of sand and pebble the remaining 3 to 5 inches would be soil.
Composted materials would be
human and animal wastes (manure), leftovers from agriculture and mariculture
(plant stems, leaves, husks, etc), papers which have been recycled several
times already, egg shells and even material left over from the processing of
plant material such as the mash (which can also be used as a feed source for
both animals and humans alike being rich in protein it is already dried and
sold as feed from the fuel grain industry).
Composting is very simple
and a natural process. It is happening all around the globe without mankind
moving a finger. However mankind has made compost heaps and does speed up the
natural process.
COMPOST: Composting,
sources of organic material for soils:
Almost
any organic material is suitable for a compost pile. The pile needs a proper
ratio of carbon-rich materials, or "browns," and nitrogen-rich
materials, or "greens." Among the brown materials are dried leaves,
straw, and wood chips. Nitrogen materials are fresh or green, such as grass
clippings and kitchen scraps.
Mixing
certain types of materials or changing the proportions can make a difference in
the rate of decomposition. Composting is being used more often in the
agriculture industry; a short table below demonstrates what can and is used in
composting today in backyards and home gardens around the world.
Following is a
chart listing common composting materials:
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Although animal droppings is
discouraged in the home compost heap, of which the table above is composed,
industrial compost heaps can and are composting such materials as human and pet
excrement.
Human manure composting has
been explored, and is used by a few people. Large-scale waste management has
yet to utilize human waste in this manner. However a good many theories and
even experiments have demonstrated that human manures can be used. There are
also other forms of waste management that are in short created biomes which
work in concert to take gray and black water and convert it into clean potable
water.
One such method employees
the removal of soils through a settling tank then running the run off water
through various streams where plants, then further fish and water animals grow
on the nutrients within the water.
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