A biotic approachto erosion control by building soil

without importing topsoil

Construction Engineering Design

• Always attempt to minimize amount of earthwork to minimum necessary

• Is intended to reduce risks as much as possible

After Construction

the erosion control part of the project start and ……

• Organic Matter Lost (usually due to removal) • Loss of micro and macro pores (air/water exchange)

The Biotic Approach Ask:

Is importing topsoil really needed for establishing vegetation and therefore

control erosion?

Natural Soil Profile

Topsoil is imported only to add the ORGANIC MATTER needed

Why Topsoil is Added?

Conventional approach to Erosion Control

A typical Standard Specifies a Minimum of 5 cm Topsoil. To achieve this it is required to transport and manage the equivalent of 25 trucks per hectare loaded each one with 20 cubic meters of soil

Biotic Approach to Erosion ControlJust what is needed

Construction Engineering Design

• Always attempt to minimize amount of earthwork to minimum necessary. However, when the Agronomic part of the project starts (erosion Control) the design criteria changes, why?

• Because the designers are usually civil engineers and because this part of the project is typically the smallest

Biotic Approach• Amend the existing soil with the right organic matter

and fertilizer and tillage the soil if needed to improve the physical conditions. By doing this vegetation can be established without the need of importing TOPSOIL.

• The Biotic Approach follows the design criteria of minimizing the amount of earthwork and Is intended to reduce risks as much as possible.

What sources of organic matter are available?

– Compost (although it can contain some nutrients, frequently it is not consistent in texture and quality and might import contaminants such as hydrocarbons, metals, pathogens, pesticides and weeds

– Peat Moss (the best source of organic matter available and the best growing medium)

Compost Sock in Toronto

Why Peat Moss is the best?This photomicrograph of a peat moss particle shows it’s natural capillary and porous structure (natural sponge). It increases many times the water and nutrient retention as compared with any other source of organic matter (compost, manure, wood, etc. The peat absorbs inside water and nutrients and avoid the leachate and loss of nutrients to the environment.

This is why it is the Most popular green house growing medium of the world.

HONEYCOMB STRUCTURE

Peat Moss• Most popular green house growing

medium in the world. • Consistent in texture and quality• Honeycomb structure holds inside water

and nutrients• Weed and contaminants free

What prevents the Peat Moss to be washed away?

Peat Moss in combination with Straw, Flexible Flax Fibers and a stabilizing emulsion or tackifier creates a stable matrix which temporarily protects exposed soil from erosion and fixes the peat on place, and works as an excellent growing medium that accelerates the grass growth that eventually will protect permanently the soil.The source of these materials?Biotic Earth ™ Growth Medium

Flexible Flax Fibers

Straw

Why Biotic Earth ™ Growth Medium

• Other mulches look for increasing the temporal protection of the soil by making the mulch last longer using synthetic materials

• Biotic Earth™ Growth Medium protect the soil but additionally are excellent growing mediums that make the grass to establish faster, reducing the risk because the planted area will be totally vegetated sooner.

The Biotic Earth ™ Growth Medium Family

• Biotic Earth™ Black

• Biotic Earth™ HGM

• Biotic Earth™ BFM

CASE STUDY

• 70% Straw with FFF (flexible flax fiber)

• 30% Canadian Sphagnum Peat Moss (growth medium)

• By volume.

Hydro Quebec James Bay

• Northern Canada• Boreal Forest• No topsoil • Short Growing

Season

We just added what was needed, THE BEST SOURCE OF ORGANIC MATTER

One Year Later

One Year Later

To mimic nature a seed mix was used

• Creeping Red Fescue• Timothy• Bent Grass• Birdfoof Trefoil• White Clover Barley• Reed Canary Grass

Bird River

Success adding just what was needed, the best source of ORGANIC MATTER

CASE STUDY

• 60 % Sphagnum Peat Moss• 40 % Straw with FFF• Mycorrhizae• Tricontonal Growth Stimulant • Micro Nutrients

Bird River Manitoba

• Manitoba, Infrastructure and Transportation Cut Slopes

• Done in 2003

2250kg/ha or 2000lbs/acre

Black HGM requires erosion protection on slopes 3:1 or steeper. C32 was used for it’s longevity.

40 days after seeding

Milner Ridge Manitoba• Government of Manitoba• Medium Security Jail• 70,000 square meter waste water pond

• PROBLEM– Very sandy material– marginal natural topsoil – not reclaimable

Very Erodible Sand

Challenge

• 70,000 square meters pond• $6.00 per square meter to import topsoil

= $420,000• Plus seeding and erosion control cost

Marginal topsoil layer

3900kg/ha 3500lbs/acre

Seed, fertilizer added right in the mix

Complete Ground Cover

Biotic Approach Building the O Horizon (mimic nature)

2 weeks later

3 weeks later

7 weeks later

13 Weeks later

Effects of mycorrhizea (a strong root system)

Biotic Layer mimic the natural O horizon

“Our Expectations of the finished product has been far exceeded”

Harry Schroeder, P.Eng, LEED AP

• 70% Straw with FFF• 20% Canadian sphagnum peat moss• 10% Tackifier and growth stimulants

Glue added during manufacturing

Peat moss added

Biotic Earth™ BFM

• Used in slopes up to 1:1• Where you need effective erosion

control and a biotic HGM

To maximize biotic performance

• Conduct a minimum of 3 soil tests to determine– Soil pH (to know if you need to add lime or sulphur)– Fertility requirements (Slow release fertilizers optimal)

– Organic content and requirements.

In challenging situations conducting these tests is critical to helping improve your vegetation in the short and long term.

Venezuela Case Study 2009A rail road embankment was constructed using sub soil in Venezuela by Astaldi (Italian company). It needed slope protection in 80 kilometres. Topsoil was specified for the construction. Because there were no sources of adequate topsoil in adjacent areas, the cost of the topsoil addition was far away out of budget.

The embankment soil characteristics were:

• pH 5 (acid)• Organic Matter less than % 2• Fertility extremely poor (P < 4 ppm, K = 10 ppm, Mineral N (traces),

Mg = 47 ppm)• Soil Particles: Sand 54.8%, Silt 18% and Clay 27.2%

SOLUTIONThe solution was to spray a layer of organic matter composed of a biotic growing medium. Before it, soil samples were taken and the soil was limed accordingly to the low pH. With the biotic growing medium, appropriate amounts of fertilizer and seeds of two varieties of grasses adapted to tropical conditions were added.

RESULTS

BEFORE AFTER AERIAL VIEW

Slope Soil Erosion was avoided due to fast vegetation growth without the addition of a topsoil layer, therefore saving a lot of money

Summary• Mimic nature (building soil)• Faster growth = lower risk• Using a Growth Medium helps • Peat moss – consistent organic material• Straw – natural wide mulch• FFF- Flexible Flax Fiber• Topsoil is not needed in most cases