Fertile Ground: Digging Deeper into Sustainable Soils
Kohler Arts Center, Sheboygan: “Life Lit Up” through Feb 21, 2016
Credit: Caleb Charland, Potato Power, LaJoie Growers LLC, Van Buren, Maine, 2012; pigment print; 23 x 29 in.
Courtesy of the artist and Sasha Wolf Gallery, NY.
Background
• Organic turf care, Earthcare Natural Lawn and
Landscapes, Milwaukee, WI
• Sales and consulting on soil fertility, Purple Cow
Organics
• Horticultural Manager, The Green Team of WI,
based in Milwaukee
• 15 year board member at Wellspring farm and
education center, Newburg, WI
Goals
•
•
•
•
•
•
Synthesize and simplify complex soil interactions
Provide broad context
Provide practical details
Recent studies
Give visuals to make soil “come to life”
Suggest resources for further exploration
It’s Not Enough To Be Local
 Quality of what we grow is essential to
maintaining and expanding our markets
 Profitability is essential
 Soil Sustainability is essential
3 Questions to Ask Ourselves
1. How do I assess soil health?
2. What are the best practices for improving soils on a
farm of my size, given that farming is a naturally
destructive process. (Destructive?)
*Short term needs vs long term sustainability*
3. What’s the most efficient way to fertilize crops?
1. Use of Resources
2. $$$
Central Premise:
Soils
Plants
Animals
Central Premise:
Soil
Biology
Soils
Plants
Animals
Living Soils
• Microbial biomass existing underground may approach
the sum of all living biomass on the earth’s surface.
(Gold,T. 1992)
• In one gram of soil: One billion bacteria cells, comprised
of thousands to millions of species. (Gans, 2005)
• In one gram of soil: Upwards to 1,000,000 fungi
comprised of hundreds of species producing over 100
meters of mycelial filaments (Lehman, 2015)
• 250,000 to 1,600,000 insects and spiders in one acre of
conventionally-cropped corn. (Lehman, 2015)
Central Premise:
(Think like a microbe)
Soils
Plants
Animals
Central Premise:
(Think like a microbe)
Soils
Plants
Animals
Central Premise:
(Think like a microbe)
Soils
Plants
Animals
Assessing Soil Health
1.
2.
3.
4.
5.
Observation: Covered? Crust? Drainage?
Smell
Ribbon Test (Google: “ribbon test CSU”)
Biology- Earthworms, Smell, Microscope
Soil Test
1.
2.
3.
4.
5.
OM
Macronutrients (P,K)
Micronutrients (S, B, Mn, Fe, Cu)
CEC
pH
Lab Testing: How to Sample
1.
2.
3.
4.
Sample 5-10 locations for a single test.
~6 inches deep
Remove root material!
Test at the same time of year (ie: fall-fall-fall or
spring-spring-spring).
5. Use the same lab for successive tests.
6. Test any areas of concern separately.
7. However, only test an area separately if you intend
to treat it differently. If you intend to treat an area
the entire way, then aggregate the sample to get an
average.
Water Soluble
Exchangeable
Total
Lab
Test
Soil Biology
LEVELS OF NUTRIENTS
Central Premise:
Soils
Plants
Animals
Central Premise:
Soils
Plants
Average:
45% Carbon
42% O2
6.5% Hydrogen
1.5% N
5% Everything else
(Minerals)
Animals
Central Premise:
Plants
Soils
Average:
95%
Air and
Water!
45% Carbon
42% O2
6.5% Hydrogen
1.5% N
5% Everything else
(Minerals)
Animals
Central Premise:
Plants
Soils
Average:
95%
Air and
Water!
45% Carbon
42% O2
6.5% Hydrogen
1.5% N
5% Everything else
(Minerals)
Animals
Humans:
65% O2
18.5% Carbon
96%
9.5% Hydrogen
3% N
4% Everything else
(Minerals)
Central Premise:
Plants
Soils
Average:
95%
Air and
Water!
45% Carbon
42% O2
6.5% Hydrogen
1.5% N
5% Everything else
(Minerals)
Minerals
= Health
Animals
Humans:
65% O2
18.5% Carbon
96%
9.5% Hydrogen
3% N
4% Everything else
(Minerals)
Central Premise:
Soils
Biology
25% Air
25% H2O
46-48% Minerals
2%-4% OM
Plants
45% Carbon
42% O2
6.5% Hydrogen
1.5% N
5% Minerals
SOIL FOODWEB
MYCORRHIZAE
N2
NITROGEN FIXATION
DECOMPOSITION
MINERALIZATION
• PARENT ROCK
• SOIL ORGANIC MATTER
NUTRIENT CYCLING
H2O
SOIL AGGREGATION
NUTRIENT CYCLING
5:1
C:N
30:1
C:N
NUTRIENT CYCLING
5:1
C:N
30:1
C:N
Eat 6 bacteria = 30:6 or too much N
NUTRIENT CYCLING
5:1
C:N
30:1
C:N
Release 5 units of N!
Eat 6 bacteria = 30:6 or too much N
NUTRIENT CYCLING
NH4+
5:1
C:N
30:1
C:N
Release 5 units of N!
Eat 6 bacteria = 30:6 or too much N
NUTRIENT CYCLING
NH4+
5:1
C:N
30:1
C:N
Release 5 units of N!
Eat 6 bacteria = 30:6 or too much N
https://www.youtube.com/watch?v=-f45sT2zECg
Root Exudates
•
•
•
•
Organic Acids
Amino Compounds
Carbohydrates
Phosphate Esters
Root Exudates
Carbon!
•
•
•
•
Organic Acids
Amino Compounds
Carbohydrates
Phosphate Esters
Root Exudates
Up to 20%
of Photosynthetic
Production
Carbon!
•
•
•
•
Organic Acids
Amino Compounds
Carbohydrates
Phosphate Esters
Root Exudates
Up to 20%
of Photosynthetic
Production
•
•
•
•
Organic Acids
Amino Compounds
Carbohydrates
Phosphate Esters
Majority of
stored carbon in
the soil
is root derived
(Schmidt et al, 2011)
Root Exudates
Up to 20%
of Photosynthetic
Production
•
•
•
•
Organic Acids
Amino Compounds
Carbohydrates
Phosphate Esters
Majority of
stored carbon in
the soil
is root derived
(Schmidt et al, 2011)
If majority of carbon in soils is root derived..
AND
the majority of carbon in microbes is root-derived…
Then roots of living plants, followed by their decay, are the
most important mechanisms for building soil carbon.
Cover Crops:
Vital key to soil health:
• Economically-wise and energy-wise
• Build SOM
• Feed soil biology through root exudates
• Top growth provides energy source for upper horizon microbes
• Capture excess nutrients and prevent leaching (keep nutrients
on your farm and not in waterways or ground water)
• Provide weed suppression (eg. oats, cereal rye, buckwheat)
• Preserve topsoil by preventing erosion
• Can be used to combat pests, eg nematodes (although reverse can be true)
Cover Crop Principles:
• Combine grasses (soil building) with legumes (N-fixing).
• Use winter-killed covers to avoid spring tillage demands
• On perennials, know the growth stage when you will
terminate the crop. Flail mower is invaluable. (Prevent a
weed issue, N-tie up etc).
• Use multiple covers seeded at the same time to combine
benefits (summer seeding particularly)
• Use allelopathy to your advantage (oats, cereal rye, sorghumsudangrass).
• Get a jump start on cover crop establishment by interseeding
an established cash crop.
• Goal of ¼ of a farm’s acreage in cover crops each year.
Common Cover Crops in Vegetable
Production
Winter-Killed Covers:
• Oats planted in early September to catch nutrients
• Sorghum-Sudangrass- great biomass producer.
• Daikon radish to break hardpan (not before/after Brassicas)
Perennial Covers:
• Cereal rye and hairy vetch planted by mid-Sept (use caution in areas
that are commonly wet in spring, allelopathy)
• White clover
Source: Managing Cover Crops Profitably, USDA/SARE publication, 2007. Available
online (free download).
Fall seeded wheat reducing dandelion growth in spring 2015 vegetable
beds. Three Brothers Farm, Oconomowoc, WI
What about compost?
•
•
•
•
•
Slow release nutrients
Improved soil structure
Diverse microbial life
Soluble forms of carbon
Microbial metabolites
Benefits of compost may be more from non-living ingredients than
the living ones (Saison et al, 2005).
• Sterilized compost compared to Non-sterilized compost. Microbial
community measured over 6 and 12 month periods based on CO2
metabolism, Phospholipid Fatty-Acid profiles, dissolved organic carbon
The soil’s native microbiology plays a larger role in the microbial
community than the introduced biology after a 6 month time
period (in-vessel study).
Important Compost Characteristics
• Source materials are no longer visible/detectable.
• Completed the heating phase to kill weed
seeds/pathogens.
• Cured- ie not residually warm.
• Smell sweet/earthy and look like the color of dark
chocolate
• C:N ratio below 25:1. *important*
• Purchased compost
– US Composting Council Seal of Testing Assurance
– OMRI listed
– Organic approval: 15 days above 130 ◦ and turned 5 times within
that period.
Simplifying Diverse Vegetable Fertility
Midwestern BioAg Vegetable program:
Crops that like 1 to 1
N to K
Brassica’s
Cucurbits
Greens
Root Crops
Potatoes
Crops that like 1 to 3
N to K
Tomatoes
Peppers
Veggies NKO 6-1-6
Veggies Sol 4-1-12
Veggies Plus (traces, Ca, humic substances)
Fertilizer Plan
Crop: Tomato
N
1. Need:
130 lbs N/A
P (P2O5)
K (K2O)
2. Nutrient Credits:
Manure
Compost:
(Get analysis
from Vendor)
Approx ¼ to 1/3
of analyzed
content
Cover Crops
Good Clover
Stand? 60 lbs/A
Soil Organic
Matter
20 lbs/A per 1%
of OM
--
--
Total Credits:
Total Nutrient
Needed:
From: Nutrient Management on Organic Vegetable Farms, (PDF), Vern Grubinger, University of
VT Extension
D’s Hierarchy of Soil And Crop Needs
Goodies
Short term:
Fertilizer
pH
Weed Management
Tillage - O2
Water
•
•
•
•
•
Fish Hydrolysate
Molasses
Kelp
Compost Tea
Humic Acids
D’s Hierarchy of Soil And Crop Needs
Long term:
Traces
Mineral Corrections
Compost
Rotations
Cover Crops
Balancing Needs
Goodies
Fertilizer
Traces
Mineral Corrections
pH
Weed Management
Tillage - O2
•
•
•
•
•
Compost
Cover Crops
Water
Rotations
Short term
Long term
What’s your vision?
How long will you farm the land you are on?
What are your prospects for renting or buying adjacent land?
How much can you remove from production in a given season?
What’s your ecological vision?
Horticratic Oath
Sources
Gans, J.; Wolinksy, M.; Dunbar, J. computational improvements reveal great bacterial diversity and high metal
toxicity in soil. Science 2005, 309, 1387-1390.
Gold,T. The deep, hot biosphere. Proc. Natl. Acad. Sci. USA, 1992, 89, 6045-6049).
Lehman, R. Michael; Cambardella, Cynthia A.; Stott, Diane E.; Acosta-Martinez, Veronica; Manter, Daniel K.;
Buyer, Jeffrey S.; Maul, Jude E.; Smith, Jeffrey L.; Collins, Harold P.; Halvorson, Jonathan J.; Kremer, Robert J.;
Lundgren, Jonathan G.; Ducey, Tom F.; Jin, Virginia L.; and Karlen, Douglas L. Understanding And Enhancing Soil
Biological Health: The Solution for Reversing Soil Degradation. Sustainability, 2015, 7, 988-1027.
Saison, Carine; Degrange, Valerie; Oliver, Robert; Millard, Peter; Commeaux, Claire, Montagne, Denis; Le Roux,
Xavier. Alteration and resilience of the soil microbial community following compost amendment: effects of
compost level and compost-borne microbial community. Environmental Microbiology, 2006. 8(2), 247-257.
Michael W. I. Schmidt; Margaret S. Torn; Samuel Abiven; Thorsten Dittmar; Georg Guggenberger; Ivan A.
Janssens; Markus Kleber; Ingrid Kögel-Knabner; Johannes Lehmann; David A. C. Manning; Paolo Nannipieri;
Daniel P. Rasse; Steve Weiner & Susan E. Trumbore. Persistence of Soil Organic Matter as An Ecosystem
Property. Nature, 2011, Oct. (478) 49-56.
Managing Cover Crops Profitably, USDA/SARE publication, 2007. Available online (free download).
Nutrient Management on Organic Vegetable Farms, (PDF), Vern Grubinger, University of VT Extension
Kohler Arts Center, Sheboygan: “Life Lit Up” through Feb 21, 2016
Credit: Caleb Charland, Potato Power, LaJoie Growers LLC, Van Buren, Maine, 2012; pigment print; 23 x 29 in.
Courtesy of the artist and Sasha Wolf Gallery, NY.
Contact Information: Darrell Smith [email protected]