Nick RamseyNatural Resources Conservation
ServiceDistrict Conservationist
610-372-4655 X110
OUR PERSPECTIVE ON OUR SOIL’S HEALTH
(Doran and Parkin, 1994)
Soil health is…“the capacity of the soil to function.”
for its intended use
Soil should…
…manage the flow of energy from the sun.…store and release
water.…cycle crop nutrients.
Soil should manage the flow of energy from the sun
Bare fields do not convert light energy into chemical
energy
Heat
Producers (plants and other photosynthetic organisms)
Chemical energy
Heat
Consumer
Consumer
Ray Archuleta
Plants: transformers of energy for the soil system
Root exudates are bacterial food.
Soil should store and release water
Soil Cover %
100%
0%30%
Rainfall Simulator
Soil Aggregate stability
In flight from Greensboro, NC to
Atlanta, GA. (April 22, 2007)
Not effective
Plant root
Runoff
Infi
ltratio
n
Runoff
Effective Physical disturbance disrupts the water cycle at the soil pore!
Glomalin (soil glue)- holds soil particles together:
• Increases infiltration
• Prevents sealing of the soil surface
Loss of SOM as CO2
CO2CO2CO2
PHYSICAL DISTURBANCE: Tillage induces native bacteria to consume soil carbon; byproduct is C02.
Tillage disrupts pore space and affects the water cycle
Soil should cycle crop nutrients
Nutrients from Fertilizer Nutrients from Soil C
NPK
Physical disturbance disrupts the Nutrient Cycle
Allow plants to feed microbes and microbes feed plants
Types of Soil Organisms
Bacteria Soil Fungi Soil Protozoa Nematodes Arthropods Earthworms
Bacteria
Bacterial Services Decomposition of OM Nutrient cycling Nitrogen fixation Nitrification Denitrification Disease Suppression Breakdown of hard to
decompose compounds
Fungi- Service they provide
•Decompose Organic Matter
•Glomalin secretion develops soil structure
•Extract nutrients•Hold nutrients
Protozoa
Nutrient mineralization
Regulation of bacterial populations
Food source themselves
Nematodes – Services they provide
A fungal-feeding nematode
• Control disease • Cycle nutrients•Disperse bacteria & fungi
A bacteria-feeding nematode
Arthropods
Earthworms
Earthworms Poor soils contain 250,000 earthworms
per acre while good soils contain 1,750,000 per acre
1 or less per shovel indicates poor soil health
10 or more per shovel indicates good soil health
Burrowing through lubricated tunnels forces air in and out of soil
Earthworm casts contain 11% of the humus 7X the nitrogen 11X the phosphorus 9X the potash
than surrounding soil
Drilosphere: Zone of earthworm influence
•Redistributes plant litter “Carbon” throughout the soil the profile • Soils are enriched with N,P, and humified organic matter•Increase water infiltration •Provide a bio pore for plant roots•Homogenize soil surface•Increase bio-diversity in soils
M.H. Beare, D.C. Coleman, D.A. Crossley Jr., P.F. Hendrix and E.P. Odum (1995)
The Soil Food Web
Typical Numbers of Soil Organisms in Healthy Ecosystems
Ag Land Prairie Forest
Organisms per gram (teaspoon) of soil
Bacteria 100 mil. - 1 bil. 100 mil. - 1 bil. 100 mil. - 1 bil.
Fungi Several yards 10s – 100’s of yds
1-40 miles (in conifers)
Protozoa 1000’s 1000’s 100,000’s
Nematodes 10-20 10’s – 100’s 100’s
Organisms per square foot
Arthropods < 100 500-2000 10,000-25,000
Earthworms 5-30 10-50 10-50(0 in conifers)
Principles to Improve Soil Health
Less Disturbance
More Diversity
Living Roots
Keep Soil Covered
Soil Health Principle 1
Manage More by Disturbing Soil Less
Agricultural Disturbance Destroys Dynamic Soil Properties
Destroy “Habitat” for Soil Organisms
Creates a “Hostile” Environment Three Types of Disturbance
Physical (tillage) Chemical (Fertilizer) Biological (overgrazing)
Stop Tilling the Soil Tillage is physical soil disturbance
Destroys aggregates Exposes organic matter to decomposition Causes compaction Damages soil fungi Reduces habitat for all members of SFW Disrupts soil pore continuity Increases salinity at the soil surface
What things change when you stop tilling the soil?
Soil pores remain continuous Soil aggregates form and are not
destroyed Soil Food Web increases and diversifies Weed seeds are not planted Water is captured and stored Bulk density increases slightly; then
stabilizes Soil fungi and earthworms increase Microarthropods increase (>20% of
nutrient cycle)
Human nature drives us to tillage!
•We enjoy power!•Feel in control!•We can see what we accomplished!
Hard to believe that the same results can be achieved using simpler biological methods!!!
Before Primary Tillage
After Primary Tillage
After Secondary Tillage
Dr. D.C. Reicosky, ARS, Morris, MN.
Less Disturbance
Also: Irrigation, Pesticides, Compaction, Fertilizer…
Overgrazing: disturbs soil and reduces root systems
30%
50%80%
60%
Soil Health Principle 2
Use Diversity of Plants to add diversityto Soil Organisms
Plants interact with particular microbes Trade sugar from roots for nutrients
Microbes convert plant material to OM Requires a diversity of plant
carbohydrates to support the variety of microbes
Lack of plant diversity will drive system to favor some microbes more than others
Impact of Biodiversity
Lack severely limits any cropping system
A diverse and fully functioning system provides nutrients, energy and water
Diversity above ground equals diversity below ground
How to Increasing Diversity in a Crop Rotation Lengthen the rotation by adding more crops
Increases soil organic matter Breaks pest cycles Improves nutrient utilization and availability Utilize available water deeper in the soil profile Provide windows for management
spread manure Plant & harvest crops
Add more plants in the current crop rotation Utilize cover crops during non-cropping part of the
year
Cover Crop Role in Diversity
1. Allow you to look at cropping periods rather than years
2. Can be used to accelerate rejuvenating soil health
3. Getting 6 to 8 weeks of growth is adequate to get some of the “rotation” effect benefits!
4. Will increase soil biological diversity “Diversity above = diversity below”
Crop Classification Warm Season
Grasses
Corn Millet
Sudan Sudex Sorghu
m
Broadleaf Alfalfa Soybean Buckwheat
Chick pea Cow pea Sunflower
Crop Classification Cool Season
Grasses Barley Rye
Triticale
Wheat
Broadleaf
Canola Clovers
Mustards
Pea Radish Turnips
Mixture of cereal rye, hairy vetch, and field peas as a winter cover crop
Mixture of cereal rye, hairy vetch and crimson clover
Keep Living Roots in the soil as much as possible
Soil Health Principle 3
Grow Living Roots Throughout the Year
Benefits: Increases microbial activity influences the N
mineralization and immobilization Increases plant nutrient/vitamin uptake/
concentrations with mychorrhizal and bacteria associations
Increases biodiversity and biomass of soil organisms
Improves physical, chemical and biological properties of soils
Sequesters and redeposit nutrients Increases OM
Root Mass in Top 4” of Soil
1-Ja
n
20-Ja
n
8-Fe
b
27-F
eb
17-M
ar
5-Apr
24-A
pr
13-M
ay1-
Jun
20-Ju
n9-
Jul
28-Ju
l
16-A
ug
4-Se
p
23-S
ep
12-O
ct
31-O
ct
19-N
ov
8-Dec
0
500
1000
1500
2000
2500
Rye & Hairy Vetch Cover Crop
Corn Grain
Soybean 7" rows
Lb
s./
ac.
A. H. Heggenstaller, University of Alberta
A. H. Heggenstaller, University of Alberta
How to Keep a Living Root All Year Long
Lengthen Rotation Add Wheat
Select Shorter Season Varieties Choose 100 -104 day Only need 6 - 8 weeks to provide benefit
Interseed into Growing Crops Planting cover crop before harvesting of cash
crop
Keep the Soil covered at all times.
Soil Health Principle 3
Keep it Covered as Much as Possible
Benefits: Control Erosion Protect Soil Aggregates Suppresses Weeds Conserves Moisture Cools the Soil Provides Habitat for Soil Organisms
Soil Temperatures
• Conserve moisture and reduce temperature.
• Crop yields are limited more often by hot and dry, not cool and wet.
When soil temperature reaches
140 F Soil bacteria die
130 F 100% moisture is lost throughevaporation and transpiration
113 FSome bacteria species start dying
100 F 15% moisture is used for growth
85% moisture lost through 95 F evaporation and transpiration
70 F 100% moisture is used for growth
J.J. McEntire, WUC, USDA SCS, Kernville TX, 3-58 4-R-12198. 1956
Soil Organic Matter Nutrient Bank Account.
1.0% OM = 20,000 # 10,000 # Carbon (5 ton)@ $4/ton = $20 1,000 # Nitrogen @ $.50/# = $500 100 # Phosphorous @ $.70/# = $70 100# Potassium @ $.40/# -=$40 100 lbs of Sulfur @ $.50/# = $ 50 Total $680
Mineralization Rate = 2-3% from Organic N to Inorganic N.
Resulting in 20 to 30 lbs of useable N per acre.
Soil Organic Matter & Available Water Capacity
Percent SOM Sand Silt Loam Silty Clay Loam
1 1.0 1.9 1.4
2 1.4 2.4 1.8
3 1.7 2.9 2.2
4 2.1 3.5 2.6
5 2.5 4.0 3.0
Berman Hudson Journal Soil and Water Conservation 49(2) 189 194 189-March April 1994 – Summarized by: Dr. Mark Liebig, ARS, Mandan, ND Hal Weiser, Soil Scientist, NRCS, Bismarck, ND
Inches of Water/One Foot of Soil1 acre inch = 27,150 gallons of water
Harvesting crop residue – What’s it worth?
Plant residue left on a field after harvest is a valuable resource. Non-market economics need to be considered when deciding to harvest residue.
Corn Residue in Nebraska:• Average cost of harvesting crop residue: $60-$70/ac.• Value of removed nutrients: ~$26/ton (1 ton corn residue has 17 lbs. N, 4 lbs., P, 50 lbs K2O, and 3 lbs. S) • Yield reduction of 6% over 5-yr. continuous no-till corn with 50% residue removed each year.
Nutrients removed can be replaced but the function of SOM can not.
NRCS, NE Fact Sheet Sept. 2008
Other Economic Trade-offs of Residue Harvest
• Potential long-term yield loss• More field passes, fertilizer & fuel use• Cost of practices to replace residue• Opportunity Costs:
– C trading– Conservation
Programs– Other uses
Grazing
Management
is the Key to
Soil Health
on
Pastureland
Grazing Management Influences…
• Vegetative cover & distribution
• Species composition
• Soil organic matter
• Soil biology
• Deposition of nutrients
• Soil compaction
• Infiltration
Contributors to Soil Organic Matter on Pastureland
• Residues from non-consumed forage
• Plant roots
• Feces from grazing animals
• Soil organisms
• Application of organic materials
Plants: transformers of energy for the soil system
Root exudates are bacterial food.
Tall Fescue Tall Fescue Tall Fescue Orchardgrass Orchardgrass Fescue/BluegrassRotational Continuous Continuous Rotational Rotational Rotational
Continuously Grazed Tall Fescue Pasture, Bath County, Kentucky
Compaction as a Soil Health Concern on Pastureland
Compacted soil limits root growth, seed germination, and infiltration.
Bare soil is compacted (crusted) by rainfall.
Compaction from hoof action is greatest on overgrazed pastures.
Compaction may be significant when animals graze or equipment is operated on wet or saturated soils.
Compaction as a Soil Health Concern on Pastureland
Proper rest periods in a managed grazing system will facilitate amelioration of compacted soil by plant roots, animals, and soil organisms.
Arrange pasture layout and the location and design of watering and supplemental feeding facilities to minimize the area of concentrated use.
HOW CAN I TELL IF MY SOIL IS HEALTHY?
Simple Test to determine soil health
“Dig a Little, Learn a Lot”
In-field soil assessment what
to look at:
Look at: Residue Soil Surface Soil Profile Plant Roots ???
Utilize all your senses:• Sight• Smell• Touch• Taste????
How compressed is your soil?
From: Cornell Soil Health Manual
Penetrometer -Measures pressure to penetrate soil
Used to identify:•Surface crust•Tightly packed crumbs•Subsoil compacted layers
Effects of compaction•Poor germination•Reduced infiltration•Poor root development•Poor air exchange
June 16, 2009Corn planted into previous years’
cover crop residue
Brown’s
RanchSame Field
July 1, 2009Rapid residue decomposition
A Spade Deep, what it tells You
• Good Soil Tilth
• Sufficient depth
• Shredded Residue
• Signs of life
What About Color?
Darker color higher OM
Topsoil & Subsoil same color
• Not building OM• Mixing of soil
profiles• Poor soil health
Topsoil clearly defined
• No mixing• Deeper layer• OM is accumulating
Does your soil smell? Earthy/Sweet Smell
Geosmin from Actinomycetes Bacteria
Decompose residue Cycle nutrients Important part of soil foodweb
Metallic/Kitchen sink cleanser Soil dominated by Anaerobic
bacteria Indicate anaerobic conditions Hydrogen Sulfide H2S rotten
egg smell, NH3 Ammonia strong urine
smell Drives pH low, release AL
No soil aroma Little active life in the soil because it is too hot, cold, wet,
dry or degraded to have many active soil organisms present at that time.
Poor Habitat
Do you have “Crumbly” Soil?
• Crumbles easily under finger pressure-GOOD
• Need a hammer to crush- BAD
What do Your Roots Say?
Healthy Roots• Uninhibited root growth• Lots of fine roots•White (no root pathogens)
Unhealthy Roots• Restricted root growth• Few fine roots•Short thick roots• Discolored & Lesions (root pathogens present)
Healthy Soil allows for Straight Roots
Compacted Layers
Roots run laterally on top of a compacted layer
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