soil health a practical approach to farming in the 21 centurynrcs practices that address soil...
TRANSCRIPT
Soil Health a Practical Approach to Farming
in the 21st Century
David Lamm National Soil Health & Sustainability Team, Leader
Why in 2013?
• World population is estimated to be at 9.1 billion by 2050 • To sustain this level of growth, food production will need to rise by 70 percent • Between 1982-2007, 14 million acres of prime
farmland in the U.S. was lost to development • Energy demands
– Increase use of biofuels (40% of corn used for ethanol) – Increase use of fertilizer (use of Anhydrous up 48%, Urea
up 93%)
Soil Health: What is It?
The continued capacity of the soil to function as a vital living ecosystem that sustains plants, animals, and humans
Soil Function to Support Agriculture
• Nutrient cycling • Water (infiltration & availability) • Filtering and Buffering • Physical Stability and Support • Habitat for Biodiversity
Soil is a Living Factory
• Macroscopic and microscopic organisms – Food – Water – Shelter – Habitat – Powered by
sunlight
• Management activities improve or degrade soil health – Tillage – Fertilizer – Pesticides – Grazing – Plant Diversity
Clear runoff from no-till f ld
No-till field
Conventional-till field
Sediment runoff from conventional-till field
Is the Buffer working? 6 /2007
Gabe Brown -ND
Ray McCormick -IN
Dave Brandt -OH
Brandon Rockey -CO Ray Styer -NC
Ecology: the study of
relationships between people, animals, and
plants, and their environment.
Interconnectedness
Soil Surface
NPK & C
Ray Archuleta
Farm or
Ranch
Characteristics of a Stable Ecosystem
Farm or Ranch Steady
State
Disrupted Soil Ecosystem
This soil is naked, hungry, thirsty and running a fever! Ray Archuleta 2007
The Battle is Won or Lost Here
Agricultural soils do not have a water erosion/runoff problem, they have a water infiltration problem.
Soil Health Planning Principles
• Manage more by Disturbing Soil Less • Use Plant Diversity to Increase Diversity in
the Soil • Grow Living Roots Throughout the year • Keep the Soil Covered as Much as Possible
Manage More by Disturbing the Soil Less
Loss of SOM as CO2
• Agricultural Disturbance Destroys “Soil Organic Matter”
• Destroy “Habitat” for Soil Organisms
• Creates a “Hostile” Environment
• Types of Disturbance – Physical (tillage) – Chemical (over application) – Biological (over grazing)
Forest SOM = 4.3 %
CT 17 yr- Soybean monoculture SOM = 1.6 %
20 c
m la
yer
Same Soils: Dynamic Soil Properties Changed!
62.8% loss of SOM after
17 yr intensive
tillage
Reicosky et al., 1995
Where the problem?
Biological Disturbance • Overgrazing • Mono-culture pasture
1. Disturbance stimulates weed (first responders)
2. Increases weed population 3. Diminishes Fungal biomass and spores- 4. Reduces infiltration 5. Increases soil temperature
6. Diminishes the habitat of the soil microbes
7. Increases the necessity for synthetic inputs
Biological Disturbance Impacts of Overgrazing
Chemical disturbances: over-application of pesticides, fertilizers and manures
Impact of Pesticides on Soil Health
• Impacts non-target organisms – not well understood – Fungicide takes out mycorrhizal fungi
• Pesticides simplify, not diversify • May restrict crop rotation • May restrict cover crop diversity
Impact of Fertilizer on Soil Health
• Short-circuits the rhizosphere & P cycle • Depresses activity of natural N fixers • Stimulates bacterial decomposition of SOM • Excess N at risk for leaching or denitrification • Increased soil salinity (Synthetic fertilizers are
salts)
Impact of Manure on Soil Health
• Can add organic matter and carbon • Build up of P to excessive levels
– Greater than 100 ppm discourages plants from feeding mycorrhizal fungi
• Other issues – Heavy metals – Salts – Pathogens – Soil compaction from application/incorporation
Cover Crop
No Till
NRCS Practices that address soil disturbance
• Nutrient Management
• Pest Management • Prescribed Grazing
Increasing Diversity in a Crop Rotation
• Growing more plants in the same rotation period – Increase soil organic matter – Breaks pest cycles – Improves nutrient availability
• Provide windows for management – spread manure – Increasing diversity in soil organisms
Use Plant Diversity to Increase Diversity in the Soil Microbes
• Plants interact with microbes – Trade sugar, carbohydrates & proteins from roots for
nutrients (Exudates) – Each plant has a unique “exudate” that attract a
specific group of soil microbes – 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 – Disturb soils are dominated by bacteria – Created the habitat for them to flourish
Biodiversity Key to Success • Lack severely limits any
cropping system • A diverse and fully
functioning system provides nutrients, energy and water
• Diversity above ground equals diversity below ground
Mimic Native Ecosystem
• Plant growth habit – Cool season – Warm season
• Plant Morphology • Broad leaf • Grass
Prairie
Forest
Crop Classification Warm Season Grasses
• Corn • Millet • Sudan
• Sudex • Sorghum
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
Role of Diversity
1. Allow you to look at cropping periods rather than years
2. Can be used to accelerate rejuvenating soil health
3. Getting 4 to 6 weeks of growth is adequate to get the “rotation” effect!
4. Will increase soil biological diversity “Diversity above= diversity below”
NRCS Practices that address Diversity
Conservation Crop Rotation
Cover Crop
NRCS Buffer Practices to Improve Diversity
Contour Buffer Strip
Cross Wind Trap Strips
Riparian Herbaceous Buffer
Field Border Filter Strip
Hedgerow
Field Border
Grow Living Roots Throughout the Year
• 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
0
500
1000
1500
2000
2500
1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec
Lbs.
/ac.
Rye & HairyVetch CoverCrop
Corn Grain
Soybean 7" rows
How to Keep a Living Root All Year Long?
• Lengthen Rotation – Add Wheat or another crop to rotation
• 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
Hairy vetch planted into corn July 17
Hairy vetch planted into bean June 29
Hairy vetch good fall growth
Photos 29 Oct 2003
Fall Biomass Data
• Lose 50% to 80% of fall growth potential with a 1 month planting delay • Later planting defers growth potential to spring • Rye is the least impacted by a later planting date
Dry Matter of Both Planting Dates Measured in November
0
1000
2000
3000
4000
5000
6000
7000
8000
Oat
s
Rad
ish+
Oat
s+A
WP
Oat
s+C
rimC
love
r
Oat
s+R
adis
h
Vet
ch+O
ats
Rad
ish
Rye
+Rad
ish
Rye
gras
s
Rye
gras
s+C
rimC
love
r
Whe
at
Rye
gras
s+A
WP
Triti
cale
Vet
ch+R
ye
Rye
Red
Clo
ver
lbs/
acre
Late Aug PlantingLate Sept Planting
0
1000
2000
3000
4000
5000
6000
7000
8000
Rye
Vet
ch+R
ye
Triti
cale
Rye
+Rad
ish
Whe
at
Rye
gras
s
Rye
gras
s+A
WP
Rye
gras
s+C
rimC
love
r
Vet
ch+O
ats
Red
Clo
ver
Rad
ish+
Oat
s+A
WP
Late Aug plantingLate Sept planting
Dry
Mat
ter (
lbs/
ac)
Cover Crop Biomass in April/May 2010
Spring Biomass Data Rye and triticale containing mixtures were least impacted by a later planting date
Ryegrass containing mixtures were moderately impacted by a later planting date
Legumes w/ no spring growing companions were heavily impacted by a later planting date
What are farmers doing!
Interseeding Annual Ryegrass
Cover Crop
Corn Silage
Field Corn
Standing Soybeans
Keep it Covered as Much as Possible
• Control Erosion • Protect Soil Aggregates • Suppresses Weeds • Conserves Moisture • Cools the Soil • Provides Habitat for Soil Organisms
Soil Temperatures
When soil temperature reaches 140 F Soil bacteria die
130 F 100% moisture is lost through evaporation and transpiration 113 F
Some 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 & 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 Soil 1 acre inch = 29,000 gallons of water
Soil Organic Matter Characteristics
• Density of SOM: 0.6 g/cm3 vs. 1.45 g/cm3 soil Bulk density =Mass (grams)/Volume (cm3)
• SOM has less density than soil so it has more space for air and water storage.
• Every Pound SOM holds 18-20# of Water! • SOM acts like a Sponge!
• 1.0% OM = – 10,000 lbs Carbon – 1,000 lbs Nitrogen – 100 lbs Phosphorous – 100 lbs of Sulfur.
• Mineralization Rate = 2-3% from Organic N to Inorganic N.
• Resulting in 20 to 30 lbs of useable N per acre.
Soil Organic Matter Nutrient Bank Account.
NRCS Practices that Keep Cover on the Surface
• No Till • Residue Management
Soil Health Planning Principles
• Manage more by Disturbing Soil Less • Diversify with Crop Diversity • Grow Living Roots Throughout the
year • Keep the Soil Covered as Much as
Possible
Soil Health Management Systems
• Collection of conservation practices that focus on maintaining or enhancing soil health
• Utilizes existing NRCS conservation practices • Incorporates the “4” soil health planning
principles • Must be implemented as a system • Farming enterprise specific
NRCS Conservation Practice Standard
• 161 different practice standards – 97 CED has lead – 21 ESD Agronomist has lead
• 13 Erosion primary resource concern • 4 Residue Management
– 9 ESD Grazing Specialist has lead • Limited number of practices to choose from • Soil Health requires more than controlling
erosion
Conservation Practices
• Must Do – Key practices that achieve the greatest
impact on soil health – Address the “4” planning principles – Cropping system specific – synergistic affect is what give the largest
return
Must Do
• Conservation Crop Rotation
• Cover Crop • No-Till System • Nutrient
Management • Pest Management
As Applicable
• Practices that address resource concerns that may not occur on all fields
• Sight specific – Irrigation water management – Buffer practices
Best Accepted New Technology
• Conservation activities that might not be in an NRCS conservation practice standard
• Improve soil health • Controlled traffic
pattern • Precision application
of nutrients and pesticides
• Use of floatation tires
Helping People Help the Land
Controlled Traffic Farming
Adjusting all farm equipment so that the same wheel tracks are used for different field operations year after year
This limits compaction to only the wheel tracks.
Soil Health Management System Templates
• Cropping system specific –Midwest –Northern Plains –Southeast –Southwest –Organic