5. Bare fields do not convert
light energy into chemical
energy
Heat
Producers (plants and other
photosynthetic organisms)
Chemical
energy
Heat
Consumer
Consumer
Ray
12. Loss of SOM as CO2
CO2
CO2CO2
PHYSICAL DISTURBANCE: Tillage induces native bacteria to
consume soil carbon; byproduct is C02.
Tillage disrupts pore
space and affects
the water cycle
14. Nutrients from Fertilizer Nutrients from Soil C
NPK
Physical disturbance disrupts the
Nutrient Cycle
Allow plants to feed microbes and microbes feed
plants
22. 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
23. •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)
24.
25. 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)
26. Principles to Improve Soil Health
Less
Disturbance
More Diversity
Living Roots
Keep Soil
Covered
27. 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)
28. 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
29. 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)
34. 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
35. Lack severely limits
any cropping system
A diverse and fully
functioning system
provides nutrients,
energy and water
Diversity above
ground equals
diversity below
ground
36. 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
37. 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”
38. Grasses
Corn
Millet
Sudan
Sudex
Sorghum
Broadleaf
Alfalfa
Soybean
Buckwhea
t
Chick pea
Cow pea
Sunflower
42. 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
46. 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
47.
48. Benefits:
Control Erosion
Protect Soil Aggregates
Suppresses Weeds
Conserves Moisture
Cools the Soil
Provides Habitat for Soil Organisms
49. • Conserve moisture and reduce temperature.
• Crop yields are limited more often by hot and
dry, not cool and wet.
50. 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
51. 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.
52. 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 = 27,150 gallons of water
53. 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
54. 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
60. 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.
61. 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.
68. 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
69. 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
Drilosphere: Zone of influence by earthworms and other microarthropods & millipedesFunction to shred and redistribute plant litter from the Detrituspherethroughout the soil profile, horizontally and vertically
Dynamic soil proprieties are those that can be influenced by human activitiesInclude: Soil Organic Matter Structure Infiltration rate nutrient and water holding capacity & availabilitySoil is Habitat that provides Food, Water & Shelter for organisms to liveAgricultural disturbance destroys habitat in which beneficial organisms could thrive and creates habitat that non-beneficial organisms can tolerate or thrive inAll three types of disturbance end in degraded soils
Here are 8 positive changes in the soil that occur when you stop tillage.Pores remain continuous-allows for increased infiltrationAggregates form – increase soil stability, improves aeration and provides habitat for soil microbesSFW – adds trophic levels and complexity, increasing functional groupsWater is held in place by increased SOM and held until plants require itBulk density decrease over time to levels that approach native condtionsSoil organisms flourish because there habitat is not being destroyed
Human’s relate hard physical work with success,
The challenge to soil health is to convince farmers that they can achieve many of the same results they are seeking when they till by using biological methodsPhotos are of tillage radish planted in a timely fashion that allows it to growing into the soil profile greater than 12”, notice the soil lineThe photo in the bottom right shows tillage radishes planted using a split row planter ever 4”. You can see the “bio-drilling that is being achieved, compares to the results that you can get with an inline ripper without the added cost of diesel fuelIn addition the tillage radish scavenge excess N, pull up P from deep in the soil profile and provide some nematode control as an added bonus
Plants exudates attract a particular variety of soil microbesMicrobes use these exudates to do the various function that support plant growth, e.g. decompose organic matter, cycle nutrients, enhance soil structure, and control populations of soil organisms including pestThe more plant exudates in the soil the wider variety of soil organisms that the soil can support, adds complexity and resilienceLack of diversity reduces the number and types of organism that can thrive, soils are less complex and lack resilienceReference the movie “Supersize Me” The movie is about a man that ate McDonalds food every meal for a month, the lack of diversity in his diet cause his blood work to get out of balance, he gained weight and his general health went down. His doctor’s pleaded with him to get off the diet. This is the same principle as feeding the soil corn exudates every year and the effect it has on the soil organisms
What impact does increasing biodiversity have on a cropping system?Lack of biodiversity limits the copping system, How?? Disrupts how soils function, less nutrient cycling, water infiltration, increase pest (weeds & diseases), etc.A diverse and fully functioning soil ecosystem means that: all the organisms that plants require are present and functioningNutrients in the soil are in the proper form for plants to take upNutrients are being held in the soil in non-leachable formsCorrect ratio of soil organisms are presentFungi to bacteriaPredator to preyWhen this occurs the system provides the energy, nutrients and water to produce cropsDiversity in plant community above ground equals or indicates a diverse soil biota
There are 2 basic ways to add plant diversity to a crop rotationLengthen the current rotation by adding more corps, e.g. corn-bean rotation goes to corn-beans-wheatBenefits include:Increase the amount of biomass produced can increase SOMPlanting difference crops breaks pest and weed cyclesPlanting a variety of shallow and deep rooted crops utilizes soil moisture and nutrientsProvides windows of opportunity to spread manure in more suitable time of the year, plant and harvest crops with out conflict, etc.Add more plants in the current rotationUtilize the non-cropping portion of the year to grow cover cropsBe sure to use multi-species cover crops when possible
Cover crops and multi-specie cover crops play a big role in adding diversity into a cropping systemFarmers are hesitant to add more cash crops to a rotation, cover crops allow for diversity to be inserted into periods of the year that normally would not have a living root growing and no exudates being placed into the soilSuccess of cover crops has always been judge by the amount of biomass produced above ground, we need to consider the amount of plant exudates that are feeding soil microbes for a period time that normally would not have gotten any food. Having roots grow for a short period of time accomplishes Multi-species cover crops will added to the biological diversity within the soil
Examples of multi-species cover crops
Graph is built on data from RUSLE2 run for Greensboro, NCIt shows the amount of root mass produced in the top 4” for corn, soybeans and a rye & hairy vetch cover cropTypical corn or soybean will only grow a living root for 100 to 110 days, leaving the soil with no living root growing for the majority of the yearAdding a multi-species cover crop growing in the non-cropping part of the year added over 2000 lbs. of root mass providing a food source year round
A. H. Heggenstaller, University of AlbertaTraditional cropping systems only have a living root growing 90 to 120 days of the yearNiches exist at both ends of the growing season that provide opportunity for cover crops to used to provide a living root
H. Heggenstaller, University of AlbertaCover crops can provide exudates to stimulate soil biology at both ends of the cropping season
There are a variety of ways to get cover crops seeded in order to take advantage of a longer growing seasonLengthen rotation, e.g. adding wheat in a C-B rotation Select shorter season varieties, need to have breeders look at higher yielding shorter season varietiesRemember having a living root growing for 6 to 8 weeks before a killing frost does provide benefitFigure out ways to interseed cover crops into growing crops
The benefits of keeping the soil covered have focused primarily on the erosion control side, we don’t need to discuss this much, thousands of HEL conservation plans have been written based on this.NRCS has totally missed the mark as providing residue all year round does more than prevent erosionCooler soils reduce evaporation and conserve moistureResidue provides habitat for soil organisms
Notice the temperature difference between bare soil and soil with cover crops.Thermometers are placed 40 feet apart in two differently managed fieldsSoil temperatures are 20 degrees cooler where cover crop is shading the soil
This is self explanatory, it shows the potential nutrients available in the SOM that can be tapped as soil health is improved and microbe activities is excellerated
This is AVAILABLE water not simply water being held in the soil profileWhat does it mean on a practical side The average increase in available water is .5” This amounts to an extra 13,575 gallons of available waterCorn water use at it maximum growth rate in the summer uses .25” to .3” of water or 6,000 to 8,000 gallonsThis amount of extra water would be equivalent to 2 irrigation events to meet corn needsThis would amount to decreasing the number of irrigation events needed orextending the time between eventsIt would also mean extra days between rainfall events before non-irrigated crops begin to stress
Using a spade or shovel to examine the soil is the best soil health evaluation tool available
This section we are trying to get the participants to learn how to evaluate existing soil health conditions using our sense and general knowledge about soil health
Measuring compaction in the field can be done using:Penetrometer: measure pressure to penetrate soil on a given day, subject to current soil moisture levels, will vary from day to dayCould use a survey flag or other type of rod to get a feel for were compacted layer occur, won’t give pressure reading but good place to start discussionsShovel is another good tool, how hard is it to get into the ground, will stop at compacted layers,
Photo are from Gab Brown’s farm in ND and demonstrate how quickly residue can breakdown when soils are healthy
Looking at a spade full of soil should begin to show evidence of soil healthHow hard was it to put the spade in the groundWere you able to get to a sufficient depth, 5” to 7”Is there sign of life, e.g. worms, millipedes, etc.Is the residue shreddedThese are all indicators of what’s happened in the past to impact soil health
Color is an indicator of soil organic matter,Should be concentrated in the surface with a clear defined, no line means mixing has been done (unless your dealing with a Molisol)
Photo is of Ray Covino, District Conservationist in Danielson, CT smelling health soil in ND.Slide is self explanatory
Using touch or feel can tell how health soils are, good soil aggregates should crumble easily under finger pressure, poor aggregates need more pressure to crush.Good aggregates are a result of following the 4 soil health principles
Roots are a great indicator of soil conditions, especially related to compaction.Roots should grow uninhibited into the soil profile, generally they hit a compacted layer at varying depths.Compacted layers that exceed 300 psi will restrict root growthRoots need a pore space greater than 0.1 mm