The Role of Soil and Successful Soil
Management in a Sustainable Garden
Jason Lilley
Sustainable Agriculture Professional
[email protected]
January 17, 2017
The Properties &
Roles of Soil in the
Sustainable Garden
The Roles of Soil in a Sustainable Garden
• Absorbs rainfall and mitigates flooding
• Removes pollutants and cleanses water
• Stores water for plants, wildlife and people
• Provides nutrients and oxygen for plants
• Stores atmospheric carbon
• Rooting zone for plants
• Provides habitat for a variety of microbes, plants and
animals
What is Soil?
• Weathered rock
• Mineral particles
• sand
• silt
• clay
• Organic matter
• living
• previously living
Soil
TEXTURE
Soil Jar Test
Class Assignment
How to determine soil types:
• Measure total amount of
soil, by height.
• Derive the % of sand, silt
and clay by measuring each
layer individually and
dividing by the total sample
amount. Percentages
should add up to 100.
TEXTURE
Feel, Squeeze, and Ribbon Test
Class Assignment
UC Davis video; Soil Texture by Feel
https://www.youtube.com/watch?v=GWZwbVJCNec
Soil Texture
Percentage of Sand, Silt or Clay
Sandy Soils
• Nutrients and water
leach away easily.
• Grow plants adapted to
sandy soils.
• Incorporate organic
matter.
• Mulch planting beds.
• Grow green manures.
Clay Soils
• Grow plants adapted to clay
soils.
• Incorporate organic matter.
• Use a garden fork to work
the soil.
• Apply mulch.
• Minimize practices that
compact the soil.
Wet or Poorly Draining Soils
• Grow plants adapted to
wet soils.
• Create raised beds.
• Divert rainwater from
the garden.
• Rainwater harvesting
• Bioswales
NRCS Web Soil Survey
Soil Web
Soil pH
Measure of the acidity or alkalinity of the soil
Soil pH affects:
• The availability of nutrients and minerals to plants
• Activity of soil microorganisms
How to Determine your Soil pH
• Home test kits
• University extension labs
• Commercial labs
Acid Soils
• Grow plants
adapted to acidic
soils.
• Incorporate compost.
• Grow leguminous
cover crops.
Alkaline Soils
• Grow plants adapted to
alkaline soils.
• Use compost and mulch
made from organic materials
such as oak leaves, saw dust
or pine needles that can
gradually lower soil pH.
• Grow vegetables and herbs
in raised beds.
Saline Soils
• Grow salt tolerant
plants.
• Incorporate compost.
• Mulch gardens.
Shallow Soils
• Grow plants adapted to
rocky habitats.
• Garden in raised beds.
• Incorporate organic
matter.
Common Soil Characteristics for the Region
Common soil characteristics in the Southern
Maine region.
• pH (acidic or basic)
• Organic content
• Soil texture
• Drainage
Bedrock Geologic Map of Maine
Successful
Soil Practices
Working with your Garden Soils:
Sustainable Soils Practices
Soil Compaction
Weight or repeated forces push soil particles together
causing them to compact.
Compacted soils:
• Contribute to erosion
• Restrict plant growth
• Limit the soil’s ability to
absorb water
• Decrease the soil’s biological
activity
Common Causes of Soil Compaction
• Construction and
maintenance equipment
Common Causes of Soil Compaction
• Construction and
maintenance equipment
• Repeated pedestrian and
animal traffic
Common Causes of Soil Compaction
• Construction and
maintenance equipment
• Repeated pedestrian and
animal traffic
• Rainfall on bare soils
Common Causes of Soil Compaction
• Construction and
maintenance equipment
• Repeated pedestrian and
animal traffic
• Rainfall on bare soils
• Continually removing
organic matter such as
leaves or lawn clippings
from the landscape
Common Causes of Soil Compaction
• Walking on, compressing or
digging in soil while wet
Common Causes of Soil Compaction
• Walking on, compressing or
digging in soil while wet
• Repeated tillage
Protect Soils from Compaction
Strategy: Restrict pedestrian and
vehicular traffic to designated pathways
Strategy: Avoid working soils when wet
Restore Compacted Soils
Strategy: Cultivate the soil lightly
Strategy: Aerate highly compacted soils
Strategy: Cover the Soil with Mulch or
Cover Crops
Considerations for Landscapes Under
Construction
• Harvest and store topsoil
for reuse.
• Protect soils with mulch.
• Use the lightest
equipment possible.
Preventing
Soil Compaction
During Construction
Maintaining Soil Fertility
Strategy: Support a Healthy Soil
Food Web
How to Protect and Encourage a Healthy
Soil Food Web
• Limit soil disturbance.
• Restore overly compacted soils.
• Regularly apply compost or organic mulch.
• Avoid pesticide use that may harm soil biota.
• Plant a diverse garden.
• Grasscycle.
• Allow plant materials to decompose in the garden.
Strategy: Convert Greenwaste into
Compost
Brown leaves
Kitchen scraps
Straw
Grass clippings
Brown leaves
Green leaves
Wood chips
Example Compost Bins
Strategy: Use Local-made, Natural Mulches
• Use local-made mulch.
• Conserves water.
• Suppresses weeds.
• Insulates roots.
• Prevents compaction.
• Prevents erosion.
• Adds organic matter.
How to Apply Mulch
• Remove all weeds.
• Spread about 3 inches deep.
• Pull back from plant base.
• Avoid mulching seedlings.
• Reapply as needed.
Strategy: Use Green Manure Cover Crops
• SOIL AGGREGATES
Appropriate Fertilizer Use
• Conduct a soil test first.
• Use appropriate amount, only
when needed.
• Choose renewable, natural
fertilizers.
• Take caution to keep nutrients
out of surface and groundwater.
Essential Nutrients
Primary Macronutrients
Nitrogen (N), Phosphorus (P), and Potassium (K)
Nitrogen (N) – Stimulates
plant root growth and the
uptake of other nutrients.
Primary Macronutrients
Nitrogen (N), Phosphorus (P), and Potassium (K)
Phosphorous (P) – Enhances
flowering, fruiting and seed
production.
Primary Macronutrients
Nitrogen (N), Phosphorus (P), and Potassium (K)
Potassium (K) –
Activates enzymes
responsible for basic plant
processes .
Macronutrients
•N, P, K
•Calcium
•Sulfur
•Magnesium
Micronutrients
• Iron
• Boron
• Copper
• Manganese
• Zinc
• Chlorine
• Molybdenum
• COMPOST NUTRIENT LEVELS
Unsustainable Landscape Sustainable Landscape
Soil is often compacted by
equipment and overuse.
Soil is a living, healthy
ecosystem.
Unsustainable Landscape Sustainable Landscape
Soils are exposed to sunlight,
rain and wind.
Soils are protected by
vegetation and mulch.
Unsustainable Landscape Sustainable Landscape
Soils require frequent
amendments to support
healthy vegetation.
Vegetation is selected that
can thrive in the existing soil
type.
Unsustainable Landscape Sustainable Landscape
Garden clippings disposed of
off-site, often in a landfill.
Garden clippings are
composted and used to
support the soil food web and
healthy vegetation.
The Role of Soil and Successful Soil
Management in a Sustainable Garden
Jason Lilley
Sustainable Agriculture Professional
[email protected]
January 17, 2017