UpdatedRootPresentation

The hidden half of agriculture

ROOTS

Bill Darrington (Persia, IA)Reading

for this week

Read the attached article and submit answers using WO before the start of class

this Friday (8/2).

1) Describe several factors contributing to deep root growth on Bill Darrington's

farm.

2) The article refers to Ray Rawson as the guru of "vertical farming"... what is

"vertical farming“ and what did Bill Darrington learn from Ray Rawson about soil

aeration?

3) Why does Bill Darrington dig so many soil pits and what does he look for?

4) What is Bill Darrington's perspective on anhydrous ammonia? Do you agree

with this perspective?

5) If you had a chance to meet Mr. Darrington, what would you want to ask him?

6) Have you ever looked at roots in a soil pit? If so, describe something you

observed. If not, when do you think you will have an opportunity to look at some

roots? What do you think you will see?

Ray Rawson

Francis Childs

VF = Management system for optimum

root extension and function

Getting dirty with 2 champions of Vertical Farming

Adapted from Hunt et al. (1986)

Tillage systems

affect root

extension and

function

http://www.farm-equipment.com/pages/Vertical-Tillage-Product-Showcase.php

shallow high-speed vertical tillage tools = VF

Shallow high-speed vertical tillage tools can be part of a

vertical farming system

main purpose = sizing residue

http://media.yetterco.com/726JDVTA.jpg

1 pass with high-speed vertical tillage tools leaves most of the

previous year’s corn roots intact, anchored and still in place.

Regardless of soil type, 22,000 – 25,000 corn root systems

per acre were observed in place.

http://www.soils.wisc.edu/extension/wcmc/2011/ppt/Klingberg.pdf

High-speed vertical tillage tools preserve root channels!

Disk ripping in late fall

at the Allison Farm

14”

“Horizontal tillage, works soil uniformly in a horizontal

plane. Years ago, horizontal tillage meant moldboard

plowing. Today, it typically involves running a field

cultivator, disk or soil finisher 3" or 4" deep in the spring

before planting. Following soybeans, it often means

doing no tillage in the fall and making one pass with a

soil finisher before planting corn in the spring. It's a

reliable way to get fast emergence and uniform stands”.

"The downside of horizontal tillage is that it creates

an abrupt change in soil density between the worked

soil and the layer at the bottom of the implement's

working depth."

Comments by Ken Ferrie in Farm Journal - September 1, 2006

“Whether a density change becomes a problem depends on

the year. Heavy rains early in the season may pond on the

sudden density change leading to nitrogen loss and plant

health problems - If it's hot and dry in July and August and

the first three sets of crown roots turn on the sudden density

layer, you won't have the root depth to get through a

drought.“

"One of our primary goals is to get the first three sets of

crown roots deep into the soil… In vertical-tillage, no-till

or strip-till conditions, the first set of crown roots will go

down. But, when we do horizontal tillage before planting-

except in a few conditions like sand-no matter what we did

in the fall, the first two sets of crown roots almost always

turn on the dense layer. Hopefully, with fall vertical tillage,

the third set will penetrate.“

Comments by Ken Ferrie in Farm Journal - September 1, 2006

Long term no-till(w/ healthy soil biology)Intensive tillage

Ontario Ministry of Ag and Food

Plow pan

Network

of cracks

and

biopores

Ken Ferrie inspecting corn roots on the Noland Farm in Blue Mound, ILWhen do roots pull out of

the ground like this?

Annual

ryegrass

roots

penetrating 40”

Biodrilling ???

Another type

of biodrill

Visual evidence of biodrilling

Rapeseed root

Canola root

So…which approach

would you use ?

Proof that you are using the

right system

John McGillicuddy

IA crop scout

Healthy

shoot growth

and high

yields

white color

proliferate

in all

directions

extensive

growth into

the sub-soil

minimal

evidence of

deformities

Efficient

use of soil

resources

The nodal root system becomes visible at ~ V1.

The nodal root system becomes the dominant

system by V6.

Understanding corn root

development

The seed roots stop

growing shortly after

the coleoptile

emerges from the

soil surface.

4 weeks

8 weeks

16 weeks

7 feet deep !!

Corn root developmentdocumented in the 1920s

If this was possible 90 years ago, just

think what is possible today?

1926

http://www.soilandhealth.org/01aglibrary/010139fieldcroproots/010139toc.html

All you need to do to grow healthy roots

is use rootworm resistant genetics… right??

When rootworm pressure is high, rootworm resistant

genetics normally result in much healthier roots

Severe damage by corn

rootworm larvae to roots of

a biotech corn rootworm

hybrid

http://www.ipm.iastate.edu/ipm/icm/2006/11-13/btcorn.html

Rootworm resistant genetics are not a silver bullet !

We have witnessed historically low densities of European

corn borers across Illinois and some nearby states that are

now believed to be linked to the widespread adoption of Bt

corn hybrids. Will we see a similar phenomenon unfold

with western corn rootworms? I suspect we might be

headed down this road. Will western corn rootworms adapt

as they have repeatedly done so in the past? If we don't

integrate management tactics, we could have the answer

sooner than we would like.

A team of ISU entomologists led by Dr. Aaron Gassman has

found evidence of root worm resistance to the Cry3Bb1

strain of protein toxin from Bacillus thuringiensis found in

Monsanto Bt corn varieties.

"We report that fields identified by farmers as having severe

rootworm feeding injury to Bt maize contained populations of

western corn rootworm that displayed significantly higher

survival on Cry3Bb1 maize in laboratory bioassays than did

western corn rootworm from fields not associated with such

feeding injury," the researchers said in an article published

on July 29 in the scientific journal PLoS ONE.

A significant correlation was found between the number

of years Cry3Bb1 corn had been grown in a field and

survival of western corn rootworm on Cry3Bb1 corn.

Interviews with farmers indicated Cry3Bb1 corn had been

grown for at least three consecutive years in all of the

fields containing resistant corn borers.

The researchers concluded insufficient planting of

refuges and non-recessive inheritance of resistance may

have contributed to resistance.

They noted a 2009 study done by the Center for Science

in the Public Interest indicated only 50% of Bt maize

planted in Midwest complied with EPA requirements for

refuge size and proximity to Bt fields.

http://cornandsoybeandigest.com/blog/bt-resistant-corn-borers-spur-concerns

“Most important, though, for effective corn rootworm

management is to consider a long-term, integrated

approach that includes multiple tactics, such as adult

suppression programs, use of soil insecticides at

planting, rotation of Bt hybrids that express different Cry

proteins, and rotation to nonhost crops. Many producers

have relied on a single tactic for too many years, and

unfortunate consequences are beginning to emerge.

As harvest gets under way this fall, I suspect that more

producers in northwestern Illinois will encounter lodged

corn that has been severely damaged by western corn

rootworms. As I learn more about this evolving situation,

I will keep you informed”.

Mike Gray – U of I Extension Entomologist

Diabrotica virgifera Diabrotica barberi

Western corn rootworm beetle Northern corn rootworm beetle

What do you know about corn rootworm biology ??

http://plantandsoil.unl.edu/croptechnology2005/plant_phys/?what=animationList


Goose

necking

European entomologists are studying natural predators of corn

rootworms (collected from soils in N. and S. America) for use in

controlling corn rootworms in Europe (where rootworms are not native)

In North and South America, corn rootworms are attacked by

many pathogens, predators and parasitoids, some of which

are specialized natural enemies of corn rootworms.

Studies have shown that

many of the natural enemies

of CRW are more common in

reduced-tillage systems, and

in fields with higher levels of

organic matter.

Journal of Economic Entomology

Article: pp. 330-339 | Abstract | PDF (1.44M)

Disruption of Host Location of Western Corn Rootworm Larvae with

Carbon Dioxide

E. J. Bernklau, E. A. Fromm, and L. B. Bjostad

Department of Bioagricultural Sciences and Pest Management, Colorado

State University, Fort Collins, CO 80523

Elevated concentrations of carbon dioxide (CO2) prevented western corn

rootworms from locating the roots of growing corn in behavioral bioassays

conducted in soil tubs. When CO2 was pumped into one end of a soil tub,

significantly more larvae were recovered from soil at the treated end than

from soil around a growing corn plant at the opposite end of the tub. In

controls with ambient air pumped into one end of a soil tub, significantly

more larvae were recovered from the soil around the corn plant than from

soil on the treated side. Larvae were unable to locate the roots of corn

seedlings when CO2-generating materials were mixed into the soil.

When damaged by corn rootworms, the roots of

some corn plants release a chemical called (E)-β-

caryophyllene that recruits an entomopathogenic

nematode (Heterorhabditis megidis) to feed on

corn rootworms.

Corn breeding has resulted in loss of the (E)-β-caryophyllene signal in

some varieties, drastically reducing their ability to recruit H. megidis.

Under field conditions, the infection rate of corn rootworms with H.

megidis were found to be 5x higher on a corn variety producing the

below-ground signal than on a variety that does not. Moreover, spiking

the root system of a non-producing variety with synthetic (E)-β-

caryophyllene decreased the emergence of corn rootworm adults

by > 50%.

Nematode diversity

FungivoreBacterivore

PredatoryPlant parasitic

competition parasitism

antibiosis induced resistance

Soil biology can both promote and

inhibit crop root growth and

function

The growth promoting effects of soil

biology are underappreciated

Dramatic effect of steam

sterilization and compost on

growth of pepper plants

Acute

root

disease

Chronic root

malfunction

VS.

This unfortunately

is the norm in

agriculture

Aluminum

toxicity

Aluminum

toxicity

Chemical toxicities

can inhibit root growth

Al toxicity is very common in

the SE US and in tropical

countries like Brazil

Understanding aluminum toxicity

Toxic forms

of Al are

bioavailable

at pHs < 5.5

Aluminum toxicity

is minimal above

a water pH of 5.5

http://www2.ctahr.hawaii.edu/tpss/research_extension/rxsoil/alroot.gif

Fe and Mn toxicities also

occur at lower pHs

What damaged these corn roots?

B was included in

starter fertilizer

http://www.sdstate.edu/ps/soil-lab/loader.cfm?csModule=security/getfile&PageID=788496

In-row fertilizer can damage crop roots

Ontario Ministry of Ag and Food

Why do crops on tiled-drained land tend to

be more drought resistant ?

Do crop roots grow toward water?

Roots elongate in aerobic soil!

Brady and Weil (2002)Brady and Weil (2002)

Sub-soil water

and nutrients

Sidewall compaction Waiting for drier soil

is the most important strategy

You really won’t know what is happening

underground unless you take a look…

All you need

is a shop-vac

and a hose!

Its just like going to the dentist!

Roots have many functions !

Carbon pumps that feed soil organisms and

contribute to soil organic matter

Storage organs

Chemical factories that change soil pH,

poison competitors, filter out toxins,

concentrate rare elements, etc.

A sensor network that helps regulate plant

growth

In addition to the most obvious functions

physical support and uptake of water and nutrients

ROOTS are:

Macro-

anatomy of roots

http://www.sparknotes.com/biology/plants/plantstructures/section2.rhtml

Micro-anatomy of roots

What is the function

of the root cap?

Physical protection

source of lubrication,

& sensor of gravity

The cell wall of the endodermis (pink inner strip of cells) is waterproofed by the

Casparian strip, which forces water to enter the symplast before it can enter the

root xylem

cortex

epidermisendodermis

root hair

phloem

xylem

The movement of fluids from the root hairs to the xylem

can occur through one of two conductive pathways– the

apoplast and the symplast.

The apoplast route consists of inter-cellular spaces

within the root cortex along which water and solutes can

diffuse.

The symplast route consists of channels through cells

along which water and solutes are actively transported.

Apoplast vs. symplast

http://www.mie.utoronto.ca/labs/lcdlab/biopic/fig/35.03.jpg

Nutrient uptake can be an active or a passive process

insid

e c

ell

ou

tsid

e c

ell

Plants are highly selective for potassium!!

Outside cell

Inside cell

K+

H+

NO3-

H+

The pH of a plant’s

rhizosphere changes as

the plant regulates its

internal charge balance.

http://departments.agri.huji.ac.il/plantscience/topics_irrigation/uzifert/4thmeet.htm

Which plant received nitrate (NO3-)?

Which plant received ammonium (NH4+)?

The ins and outs of plant nutrition

Transpirational

stream

H20

H20

Root exudates

activate soil microbes

Ro

ot g

row

th

N, S, P

Diffusion

Microorganisms produce

most but not all of the

enzymes need to digest OM

Plants take up mostly inorganic forms of nutrients

when inorganic forms of nutrients are readily available

In some natural ecosystems (e.g., tundra), organic

forms of nutrients are very important

Water moves upward

through plants

whenever there is a

negative gradient of

water potential along

the soil-plant-

atmosphere

continuum

Why does

water move

up into

plants?

H20

H20

H20H20

A continuous

chain of water

molecules is

pulled up

through the

plant

Solar energy

drives the

process

Plants provide

the conduit

Rhizosphere

Zone of root

influence

The rhizosphere is

normally << 10 % of

topsoil volume

Roots normally

occupy < 1% of topsoil

volume

Navigating the rhizosphere

Rhizoplane

Endo-

Rhizosphere Ecto-Rhizosphere

End of the

rhizosphere

(Lavelle and Spain, 2001)

< 10% of soil

volume

> 90%

of soil

volume

Mic

rob

ial acti

vit

y

A few millimeters

Healthy

cowpea

nodule

with a

pink

interior

Legume

nodules

come in

many shapes

and sizes

Legume

love

affair

Sarrantonio

Lots of complicated biochemistry – very intensively studied!!

Examples of rhizobia innoculant

Alfalfa Group

(Rhizobium meliloti)

Alfalfa

Black medic

Bur clover

Button clover

White sweetclover

Yellow sweetclover

Clover Group

(Rhizobium trifolii)

Alsike clover

Arrowleaf clover*

Ball clover

Berseem clover

Crimson clover

Hop clover

Persian clover

Red clover

Rose clover*

Subterranean clover*

White clover

Cowpea Group

(Bradyrhizobium japonicum spp.)

Alyceclover

Cowpea

Kudzu

Peanut

Lespedeza

Soybean has its own inoculation group!!

Inoculation groups for commonly grown legumes

How much N do soybeans fix and how much

of this N is left behind after harvest?

A good soybean crop will fix >150 lbs of N/ac but

>200 lbs of N may be removed in the harvested beans.

N

-N

crop rotationsHistorically

revolved around LEGUMES

Mycorrhizae - internet of the soil

Ectomycorrhizae

Arbutoid

mycorrhizae

Ericoid

endomycorrhizae

Orchid endomycorrhizae

AM endomycorrhizae

2 main types of mycorrhizal associations

Lavelle and Spain (2001)

•Many plants are

connected

underground by

mycorrhizal hyphal

interconnections.

•Mycorrhizal (AM)

fungi are not host

specific.

Illustration by Mark Brundrett

Mycorrhizal Networks: Connecting

plants intra- and interspecifically

Increase nutrient (P) uptake suppress pathogens

Mediate plant competition Improve soil structure

Glomalin

Superglue

of the soil ??

There are many

mycorrhizal

inoculants on the

market and some

evidence that they

work but it is

important to keep in

mind that they are a

much less proven

technology than

legume inoculants

There are lots of examples of dramatic

responses to mycorrhizal inoculation in

reforestation projects

Is this really possible?

Tree roots often extend >2 times farther than the canopy

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