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How do we define a health soil?
A healthy soil:
• has a stable soil surface,
• is increasing in SOC or is at the maximum level for the location,
• has a microbial population that efficiently decomposes organic residues,
• does not contain P, N, or herbicides and pesticides in sufficient quantities to cause water quality problems in the event of an unexpected erosional episode
• is regenerative under its intended land use or management system.
Is our soil unhealthy?
What is the “Canary in the Mine” of the Soil ?
What do most of our soil tests show today?
What really determines the potential Soil Organic Matter in a given area?
4
0 20 40 600
25
50
75
100
Carb
on c
onte
nt %
Reduction in the Carbon content of the soil with time of soil use
Years under tillage cultivation (Bauer & Black, 1983)
%
North Dakota Farm Research
What is the most limiting natural resource in your forage/crop production system?
Sunshine?Minerals?
Water?
Monday, June 12, 2006 8:30am Rainfall: 1.8 inches
Disk No Cover Disk Cover
No Tillage CoverNo Tillage No Cover
JSWC C.W Raczkowski 2009
CT= 119 tons/6 years89% lost in 3 rain events (June 97, June 2000 and Sept 2000
NT= 7.1 tons/6 years
3.8%-6.2% slopes
6 year study
Forest SOM = 4.3 %
CT 17 yr- Soybean monoculture SOM = 1.6 %
20
cm
la
yer
This is the same soil- What happened?
Both soils started with the same Inherent soil Properties soil:
•climate (precipitation and temperature) •topography (shape of the land) •biota (native vegetation, animals, and microbes) •parent material (geologic and organic precursors to the soil) •time (time that parent material is subject to soil formation processes)
62.8% loss of SOM after 17 yr intensive
tillage
Dynamic properties depend both on land management and inherent properties of the soil: • organic matter,• soil structure, • infiltration rate, • bulk density, • and water and nutrient holding capacity.
62.8% loss of SOM after 17 yr intensive
tillage
Disrupted Soil Ecosystem
This soil is naked, hungry, thirsty and running a fever!
Ray Archuleta 2007
When soil temp reaches. . .140°F
130°F
100°F
70° F
Soil bacteria die
100% moisture lost through evaporation & transpiration
15% moisture is used for growth 85% moisture lost through evaporation & transpiration
100% moisture is used for growth
J.J. Mc Entre, USDA SCS, Kerrville, TX, 1956
Physical Disturbance in the form of tillage destroys the
biological and ecological integrity of the soil ecosystem.
1. Disturbance stimulates the first responders--increased weed population
2. Destroys soil pores by shearing and smashing-impacts infiltration
3. Diminishes the soils ability to respire
4. Disrupts the habitat of most microorganisms arthropods
5. Simplifies the soil fauna over time -fungi don’t like disturbance -Mycorrhizal fungi – uptake of P, Zn, Cu, Fe
13
Mineralisation of Organic Matter
>Erosion
Consequences of tillage
The USDA estimates that about half the fertilizer used each year in the US simply replaces soil nutrients lost by topsoil erosion.
(David Montgomery, 2007)
25 yrs of conventional corn
20 yrs of bluegrass, then 5 yrs conventional corn
Water stable
aggregates
After adding water
Soil Health
Type of Organism number/acre pounds/acre
Bacteria 800,000,000,000,000,000,000 2,600
Actinobacteria 20,000,000,000,000,000 1,300
Fungi 200,000,000,000,000 2,600
Algae 4,000,000,000 90
Protozoa 2,000,000,000,000 90
Nematodes 80,000,000 45
Earthworms 40,000 445
Insects /arthropods 8,160,000 830
Soil Food Web
Rhizosphere
Number one food source of most soil organisms is a living root.
Living roots release many types of organic materials into the rhizosphere around the surface of the root
Rhizosphere
The number of organisms in the rhizosphere is up to 2000 times higher than in the rest of the soil.
Plants Interacting with Mycorrhizal Fungi
Assists with P uptake from the soil
Moves P from the non-legume plant to the legume plant
Moves N from the legume plant to the non-legume plant
The Nature and Property of Soils, Brady and Weil
Ranching/Farming in the 21st Century-a practical approach to soil health
Manage more by disturbing less
Diversity is Critical
Living Roots feed your soil livestock
Keep the soil covered
Integrate livestock
The quality of our lives depends on
the food we eat
the water we drink
and the air we breath.
All of those things depend on
the quality of the SOIL.
Charles Kome
Expand your knowledge - Read a Book
The Nature and Properties of Soils by Brady and Weil
Holistic Management by Allan Savory
Agroecology by Gliessman
The One Straw Revolution by Masanobu Fukuoka
Teaming with Microbes by Lowenfels and Lewis
Soil Biology Primer by Elaine Ingham
The Worst Hard Times by Timothy Egan
Collapse by Jared Diamond
Dirt-The Erosion of Civilization by David Montgomery