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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
Q
F
S
G
E
D
T
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