A new look at cover crops and carbon
management in our local agricultural
systems
Glenn McGourty, Farm Advisor
UCCE Mendocino and Lake Counties
Ecological Services of Your
Vineyard and Property
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Watershed
Habitat for native species
Pollinators
Carbon sequestering and cycling
Nutrient cycling
Energy cycling through photosynthesis,
production of O2
Urban separation and viewshed
Vineyard Floor Management Objectives
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Be cost effective
Enhance vine health
Increase or decrease vine growth by management
practices
Improve soil health (bio activity, soil structure,
water retention, water infiltration)
Firm footing for vineyard operations
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Control weeds
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In the beginning…
Negative Effects of Tillage:
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Loss of OM
Decreased infiltration
of air and water
Loss of soil structure
Loss of soil biological
activity and diversity
Carbon Sequestering and Climate Change:
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Increase of
atmospheric CO2
from human
activity
Loss of carbon
from soil by tillage
= 30% of total
CO2 generated
Farming for Carbon
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Emphasis on managing soils to accumulate
stable carbon
Focus on natural processes
Soil amendments may also be needed
Changes in tillage practices
Don’t add more CO2 from soil or fossil
fuels
Possibility of carbon credits?
Goals in Improving Soil Chemistry and
Fertility with Organic Matter
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Increase in soil N
Improved availability of K, S, and P
Improved availability of micronutrients
(especially if composts used)
Increased soil buffering capacity
Increased soil CEC
Increase bio activity, both macro and micro
Vineyard Organic Matter
Per Year, lbs /acre
Item
Prunings
Conventionally
Farmed
900 lbs.
Organic/ BD .
Farmed
900 lbs.
Leaves
1200
1200
Weeds/cover c.
1000
1000-10,500
Compost
Total, tons/acre
0
1.5
2000
1.5—7.5 t
North Coast Soil Issues:
Problems:
 Low pH
 Low Calcium
 High Magnesium
 Low Potassium
 High clay, poor soil
structure
 Phosphorus
deficiency
Solutions:
 Apply Gypsum or
Lime
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 Potassium sulfate
 Initial ripping, cover
crops, reduced tillage
 Rock phosphorus,
compost high in P
Soil Structure and
Organic Matter
Improving Soil Physical Quality
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You can manage soils to increase SOM
Increased SOM often means improved soil
structure
Change soil structure from blocky to granular
Increased soil porosity and lower bulk density
with more carbon
Improved water holding capacities, infiltration
rates
Thanks to those you don’t even
see…
Deep Tillage is Important Initially
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Rip to rooting depth
Don’t destroy soil structure
Apply nutrients and
amendments that are difficult
to leach before ripping
Vineyard Floor Management:
Tillage
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Disking
Spading
Under the vine cultivation
Mowing
Alternative Cultivation Equipment
Cover crops
and their effects in vineyards
Cover Crops
Prevent
erosion
Attract benefical
insects
Increase diversity
of soil organisms
Improve soil
structure
Retain soil moisture
Affect micro-climate
Increase organic material
and soil fertility
Source: A. Thrupp
Soil Protection With Cover Crops
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Cover crop foliage shields soil from rain
splashing, slaking of aggregates
Water infiltration rates stay elevated
Improved water storage, water quality
OM conserved by preventing erosion
Mulching effect keeps soil cool in summer,
protects OM from oxidation
Immediate Effects of Cover Crops
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Plant tissue is the primary source of SOM
Soil life is stimulated
Cover crops serve as food source for
vertebrates, invertebrates and microbes
Soil respiration rates and microbe numbers
increase
SOM Forms Quickest Under Sod
Culture
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Root biomass cycles annually
Mulching effects conserve moisture, protect the
SOM from sunlight and oxidation
Summer Vineyard Floor
Management
Cover Crop Types
Grasses and Legume Mixes
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Complimentary in
growth
Good for improving
soil structure, tilth
May also improve
soil fertility
Grasses: Fibrous Roots
Peas, Vetch, Bell Beans and Oats Cover Crop
Fitting the Architecture
of the Vineyard
vs
Self Reseeding Annual
Legumes
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Protect the soil and help water quality
Produce N (15-30 lbs/acre)
Self Reseeding, no tillage needed
Habitat for beneficials
Potentially good forage for grazing
Works best in higher rainfall areas, or vineyards
with sprinklers to help germinate seed
Crimson Clover
Trifolium resupinatum
Subterranean Clover
Trifolium subterraneum
Bur Medic
Medicago polymorpha
Balansa Clover
Trifolium michelianum
Well Mixed Sward
Spring Dry Down
Seed Production
Perennial Cover Crops
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Can greatly reduce vigor
Recommended for fertile sites
Grass and legume mixes useful, but not annual
and perennial species
Grasses: turf-type tall fescue, sheep fescue,
creeping red fescue, hard fescue, perennial
ryegrass
Legumes: white Dutch clover, Ladino clover,
strawberry clover—watch out, gopher magnets!
Tall Fescue
Festuca arundinacea
California brome
Bromus carinatus
What is right for your vineyard or
farm?
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Sprinklers available?
What will grow on native rainfall?
What will tolerate cold weather and
dryness?
Insectary Plantings
Habitat For Beneficials
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Shelter
Nectar
Alternate prey
Pollen
Can assist your
vineyard in creating
self-regulation for
pest control
Dedicated Insectary Rows
Parasitoids
Predators
Wild Carrot or Queen Anne’s Lace
Daucus carota
Compost and Organic Matter—
Helping Your Soil Come Alive
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Recycled Pomace
Manure, lime,
gypsum
Produced on Farm
or Winery
Process takes
about one year
Applied at one or
two tons/ acre
Nitrogen in Compost
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r
r
r
r
Available N = mineral N in the root zone
Mature composts: typically 1 - 3% N=
20 -60 lbs of N
Unincorporated materials: Effective applied
to cover crops before rains
Incorporated materials: may release N or
immobilize N in short term
Other Minerals in Compost
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.5-1.0% P (10-20 lbs per ton)
.5-3 % K (10-60 lbs per ton)
Numerous micronutrients
Compost Applications: Beneath
vines or across the vineyard floor
Vineyard Floor Management:
Wooly Mowers
Useful Tools for
Maintaining Sheep
Leaf Pulling by Sheep
Aggressive Leaf Pulling by Sheep
Helpful Resources
Available: UC ANR Press:
http://anrcatalog.ucdavis.edu/
Thanks for your attention!