Improving Soil Structure & Case Studies

Eric Berntsen

State Water Resources Control Board

SEVEN PRINCIPLES of River-Friendly LANDSCAPING

1. Landscape Locally 2. Landscape for Less to

the Landfill 3. Nurture the Soil 4. Conserve Water 5. Conserve Energy 6. Protect Water & Air

Quality 7. Create Wildlife

Habitat

3. NURTURE THE SOIL

• Protect from erosion and compaction

• Build “living soil” with organic compost and sheet mulching

• Apply organic mulch to protect and enrich soil

• Feed soils naturally and avoid synthetic, quick release fertilizers

"The history of every nation is eventually written in the way in which it cares for its soil" Franklin D. Roosevelt

What happens when we maintain/improve soil quality?

• More nutrient and water retention

• Less need for fertilizer, pesticides, etc.

• Filtering and decomposition of toxins

Ideal Soil Structure for Plant Growth

Mineral45%

Organic Matter

5%

Water25%

Air25%

Soil Texture

Particle Percentage

Total depth = 4 inches Sand depth = 1 ½ inches

1.5 divided by 4 = .38x100= 38% (40)

Silt depth = 1 ¼ inches

1.25 divided by 4= .31x100=31% (30)

Clay depth =1 ¼ inches

1.25 divided by 4= .31x100=31% (30)

Soil Textural Triangle

BUILD “LIVING SOIL”

• Healthy soil biology, full of micro-organisms forms the foundation for the entire site ecology

• Similar to the role of plankton in the ocean

· Creates soil structure

· Stores and cycles nutrients · protect plants from pests

· Improves water infiltration and storage

· Filters out urban pollutants

LIVING SOIL STRUCTURE

PROTECT FROM EROSION AND COMPACTION

• Stockpile topsoil for later use in the landscape. (max 6’ height)

• Protect stockpiles from erosion

• Specify earthwork construction during the dry season

• Control equipment and foot traffic on site and protect planting areas from damage and compaction

• Coordinate with utility layout and design

• Aerate compacted soils and incorporate compost

Healthy Soil Food Web Benefits

• Suppress Disease (no more pesticides!) • Retain Nutrients (reduce run-off,

leaching) • Nutrients Available at rates plants

require (eliminate fertilizer) • Decompose Toxins • Build (re-build) Soil Structure • Reduce Water Use, increase water

holding capacity, rooting depth

Fungi attacked by bacteria in

anaerobic conditions

Fungal hypha

Bacteria DIC Microscopy;

250X

Ciliates – “Soil Salmon”

Compost • Restores soil biology - contains over 1 billion

microorganisms in one teaspoon

• Forms soil aggregates, allowing air and water to flow through. Turns soil into a “sponge” able to absorb and infiltrate onsite water

• Organic Compost preferred over nitrified sawdust – contains living organisms that feed soil web

• Certified compost – OMRI, STA

• General guidelines: 2”- 4” tilled into top 6” – 12” soil

BUILD “LIVING SOIL” Sheet Mulch composts weeds or lawn in place

UTILIZE MULCH

• Apply minimum 2” layer mulch over all planting beds

• Utilize local, recycled, organic mulch from tree trimmings

• Avoid forest product mulches

• Reapply as needed

• Keep away from root crowns and trunks

Case Studies

Landscape irrigation runoff (aka. “urban slobber”) is a major cause of

water quality pollution…

….we can improve water quality by

• keeping more rainwater on site (rainwater harvesting); and

• creating landscapes that require less water

REQUIRED IN NEW STORMWATER PERMITS!

Good News – the Model Ordinance achieves Waterboard interests…

• Soil Management Report gets at soil quality

• Landscape Design Report gets at the non-structural stormwater BMPs

• Irrigation Design Report gets at the “urban slobber” issue

Building a Rain Garden

The Farm on Hurley Way August 29, 2009

9-11 AM Instructors: Eric Berntsen and Greg Gearheart

California State Water Board, Sacramento

Rain Gardens http://learningstore.uwex.edu/pdf/GWQ037.pdf

• Three Questions

– Where do I put the rain garden? • at least 10 feet away from foundation, not over

septic, etc. – How big to I make it?

• depends on soils, area draining to it, depth, and slope. Need to provide berm.

– What do I plant it with?

• Larger gardens can support more diversity. Must use plants that are moisture tolerant (e.g., Carex barbarae)

• Larger gardens can accommodate more diversity

Plant List for Hurley Rain Garden

Symbol Scientific Name &

Common Name

Plant Count

(280 ft2 area)

Height Soil

Type/Drainage

Sunlight

Requirements

Other

Genus: Carex

Tumulicola

Berkeley Sedge

14 2ft Tall All Soil Types Full Sun Evergreen Grass-Like. Can be mowed to about

8".

Genus: Mulenbergia

Rigens

Deergrass

6 5ft Tall All Soil Types Full Sun Evergreen Grass. Can be inundated with water.

Recommend some summer irrigation to maintain

appearance.

Genus: Juncus

Effusus

Common Rush

12 4ft Tall All Soil Types Full Sun Evergreen Grass-Like. Requires summer

irrigation.

Can be inundated with water.

Genus: Mimulus

Guttatus

Seep Monkey Flower

30 1ft Tall All Soil Types Full Sun Annual or winter dormant perennial. Requires

summer irrigation. Yellow flowers in spring.

Genus: Carex

Elata

Bowles Golden Grass

16 2.5ft

Tall

All Soil Types Full Sun Needs ample moisture. Will grow in standing

water.

Genus: Koeleria

Macrantha

June grass

4 2ft Tall All Soil Types Full Sun Perennial. Recommend occasional summer

irrigation for appearance.

Genus: Juncus

Patens

Common Rush

6 2.5ft

Tall

All Soil Types Full Sun Evergreen grass-like plant. Requires summer

irrigation. Can be inundated with water.

Genus: Potentilla

Glandulosa

Sticky Cinquefoil

30 2ft Tall All Soil Types Full Sun Perennial. Requires summer irrigation. White to

yellow flowers in spring.

Genus: Bidens

Laevis

Joaquin Sunflower

20 1ft Tall All Soil Types Full Sun Annual or perennial. Requires summer irrigation.

Small yellow flowers in summer. Can be

inundated with water

Genus: Deschampsia

Caespitosa

Tufted Hair Grass

8 2ft Tall All Soil Types Full Sun Evergreen grass. Requires summer irrigation.

Can be inundated with water

P

B

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F

S

G

E

D

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J

Sources of Information

• Soil Biology Primer (http://soils.usda.gov/sqi/concepts/soil_biology/biology.html)

• River-friendly landscaping guidelines

(www.riverfriendly.org)

• Soil Science Simplified andTeaming with Microbes

• Sustainable Landscape Construction—A Guide to Green Building Outdoors By J. William Thomson and Kim Sorvig

Sources of Information

Eric Berntsen 916-341-5911

eberntsen@waterboards.ca.gov