Building Healthy Soils

Fred Magdoff

fmagdoff@uvm.edu

The Great Hunger of 2008

Rioting in response to soaring food prices recently has broken out in

Egypt, Cameroon, Ivory Coast, Senegal and Ethiopia. In Pakistan and Thailand, army troops have been deployed to deter food theft from fields and warehouses.

Intensive tillage, soil erosion, and insufficient

added residues

Soil organic matter decreases

Surface becomes compacted, crust forms Less soil water storage, less diversity of soil organism, fewer nutrients for plants

Aggregates break down

More soil organic matter is lost

Crop yields are reduced

Increased erosion by wind and water

Hunger and malnutrition result

Soil Degradation

… it is our work with living soil that provides sustainable alternatives to the triple crises of climate, energy, and food. No matter how many songs on your iPod, cars in your garage, or books on your shelf, it is plants’ ability to capture solar energy that is at the root of it all. Without fertile soil, what is life?

—VANDANA SHIVA, 2008

% of aggregates

stable to 1.25cm

rain/5mins:

2mm sieves

Organic

management

~70% - high

Conventional

management

~20% - low

Aggregates after stability test

Add organic matter

Increased biological activity (& diversity)

Decomposition

Nutrientsreleased

Aggregationincreased

Pore structureimproved

Humus and othergrowth promotingsubstances

Reducedsoil-borne diseases,parasitic nematodes

Improved tilthand water storage

HEALTHY PLANTS

Harmful substances detoxified

crop harvest

carbon dioxide (CO2)(0.04% in the atmosphere)

erosion

photosynthesis

root

respiration

and soil

organic

matter

decomposition

carbon in

soil

organic matter

respiratio

n

in stems

and

leavescrop and

animal

residues

a) create soil & above ground conditions forhealthy plants with enhanced defenses

b) stress pests

c) enhance beneficials

Overall strategies of ecologically-based agriculture

Build internal strengths into agricultural

ecosystem

Prevention (of symptoms and consequences of weak

ecosystem)

Routine ecologically sound practices during season to keep plants

healthy

Reactive management

Preventive managementpre-season through planting time

(building internal strengths into the system)

create soil & above ground conditions forhealthy plants with enhanced defenses

stress pests

enhance beneficials

1. Crop/plant selection & planting management;

habitat conservation & enhancement of field

and surroundings

2. Build healthy soil (below ground

habitat conservation & enhancement)

1. Add plentiful amounts of organic materials from crop residues (including cover crops) well as off-field organic materials such as animal manures and composts.

Building Healthy Soil

vs.

2. Keep the soil covered with living vegetation and/or crop residue.

Building Healthy Soils

• Supplies food and habitat for maintaining biodiversity (helps beneficials at expense of pests)

• Suppresses weeds, insect, and disease cycles

• Helps grow healthier plants because:

a) development of better soil tilth

b) supplies nutrients and soil holds water better

c) lessens compaction

d) etc.

Use cover crops or perennial sod cover routinely.

Reduce tillage intensity.

3. Use better crop rotations.

Building Healthy Soils

Building Healthy Soils

4. Reduce tillage intensity.

Many different reduced till systems —conservation till, ridge till, zone-till, no-till.

Better planters help.

Cover crops can help.

Building Healthy Soils

5. Use other practices that reduce runoff and erosion.

6. Reduce severity of compaction.

Building Healthy Soils

Don’t travel on wet soils.

A lasting injury is done by ploughing

land too wet.

S.L. Dana, 1842

Use controlled traffic lanes (“permanent” beds).

Better load distribution.

Increase organic matter.

Etc.

Building Healthy Soils

7. Use best management techniques to supply nutrients to plants without degrading the environment.

fertilizers,

lime, organic

amendment

s

leaching,

runoff, and

volatilizatio

n

crops

farm-grown crops

soil

crop

residues

Farm boundary

Nutrient Cycles vs. Nutrient Flows

Healthier Crops

Better

rotations

Reduce

compaction

Add various sources of

organic materials (crop residues,

manures, composts, etc.)

Cover crops

Reduce

tillage

Control

erosion

Better nutrient

timing, placement,

and amounts

Use

Multiple Tactics