Rhizosphere Affects on Soil Quality Slake Test Demonstration - - PowerPoint PPT Presentation

• “Rhizosphere Affects on

Soil Quality”

Slake Test Demonstration Infiltration Test

George D. Derringer

Resource Soil Scientist Southwest Ohio 937-836-5428 Ext. 107

Forest SOM = 4.3 % CT 17 yr- Soybean monoculture SOM = 1.6 %

20 cm layer

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

Grassland Soils

Natural soil ecosystems: Have a diverse living growing root in the soil at all times- generally nutrients don’t leak Man’s agroecosystems- leak nutrients: 2/ 3 of year the soil is bare in the corn belt!

Mimic Nature: The Supreme Farmer.

What holds the Porosphere together?

From ATTRA - Soil Quality Publication

No-till Conventional tilled Maintenance mode Repair mode Grass systems

OHIO (2010) BIRD’S EYE VIEW

Productive factory workers

Decomposition active zone Aggregation active zone

Zone of aggregation in layers This enrichment of the surface layer with SOM maintains soil quality by enhancing aggregation and facilitating aeration (Doran and Parking, 1994; Franzluebbers, 2007).

Hierarchical Approach to Understanding Soil Function Rhizosphere Drilosphere Aggregtusphere Detritusphere Porosphere

Rhizosphere

The number of bacteria negative gram in the rhizosphere is from 5 to 2000 times larger than in the regular soil.

Managing for microbial habitat in the soil

 Less Disturbance of the soil.  More diversity in what is grown in the soil.  Living roots in the soil as much as possible.  Keep the soil covered with crops and their residues.  These are the ‘keys to the kingdom’ of improving soil quality

and sustainable agriculture because they focus on soil biology and soil ecology; what really runs the soil and all that it does.

IF YOU BUILD IT THEY WILL COME

First you have to create a habitat for all the organisms that live in

the soil

No Tillage will be the best, and then conservation or minimum

• tillage. Anytime you can have a forage or pasture phase in the

rotation you will be creating and maintaining an undisturbed habitat.

Even what appears to be a derelict soil there will be a number of

microorganisms that are in resting stages waiting for the right condition: one earthworm per square metre can become 10 or more in one season given a good food source and the right conditions.

The Detritusphere: . Protects the aggratusphere and the poroshpere from the sun, wind and rain

• Lowers temperture and evaporation
• Provides habitat and food for soil
• rganisms
• Enhances biogeochemical nutrient cycling
• Builds soil structure and nutrient reserves
• 20 percent of total carbon energy for soil

FOOD WEBS

Soil food webs are mainly based on three primary

carbon (C) sources: root exudates, litter or residues, and soil organic matter (SOM). These C sources vary in their availability and accessibility to soil

• rganisms, and can thus, increase the C flow and

biodiversity within the food web.

SOIL IS A LIVING, BREATHING, ENERGIZED COMMUNITY OF ORGANISMS

Arthropods

Aboveground diversity is a mirror for belowground diversity

HOW COVER CROPS WORK TO INCREASE BIODIVERSITY

 Increase the quality and quantity of soil organic matter  Remember it is not just about the above ground residues, roots are the most

available source of organic matter in the soil.

 The rhizosphere (rooting zone) is the most biologically active part of the soil  Roots leak carbohydrates, amino acids, organic acids, and a number of

• ther complex compounds that feed the microorganisms in the

rhizosphere

 Each plant species leaks its own unique signature of compounds into the

rhizosphere.

 The more diverse the plant community above ground the more

diverse the community below ground

 A greater diversity of soil services

Enlarged Soil aggregates Glomalin and hypae

• Dr. Kris Nichols, Microbiologist, ARS, Mandan, ND

Root and Mycorrhizal Fungi Association:

vasicular-arbuscular mycorrhizal (VAM) fungi Rhizosphere

Dennis Froemke ND Area Range Specialist

Soil Engineers: Earthworms Subsoil macropores - Model of earthworm burrow systems

• 75 ind/m2
• 30% endogeic (∅ 2-3 mm)
• 70% anecic (∅ 6 mm)
• ∅ core 212 cm

Bastardie, Capowiez et al. Biol Fertil Soils (2002) 36:161–169

1 m 1 m

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. Colem an, D.A. Crossley Jr., P.F. Hendrix and E.P. Odum ( 1 9 9 5 )

EARTHWORMS & OTHER SOIL ANIMALS LIKE MUSTARD AND CANOLA

Photo by Francis Yeatman

BI ODI VERSITY

Flexibility Resilience Resistance The ultimate insurance!

WORKING WITH ROOTS

Each Plant Species has

different:

Root Exudates Root biomass and

architecture

Architecture affects the: Distribution and number of

• rganisms

Soil stability Amount of habitat Amount of exudates

Rooting depths

Creating a root canopy

Deep Moderate Shallow Alfalfa Barley Pea Safflower Canola Flax Sunflower Wheat Lentil Buckwheat

Loss of SOM as CO2

CO2 CO2 CO2 PHYSI CAL DI STURBANCE: Tillage induces the native bacteria to consum e soil carbon; byproduct is C0 2.

Tillage disrupts Drilo- Poro-Detritus-Rhizo-and the Aggregtus-sphere

Aboveground diversity is a mirror for belowground diversity