Soil health overview

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Soil Health ↔ Soil Function

Kitty O’Neil, Ph.D.

Cornell Cooperative Extension, NNY

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Soil Health ↔ Soil Function

• At the end of the hour…

–Understand the functions of soil and their dependence on soil composition and structure

– Explain to someone what soil is made of , how it’s organized and how it behaves

– Think of some ideas how you might preserve or improve your soil health

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Why do we care about soil?

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Why do we care about soil?

• Soil resources were and are a central factor in shaping human history and development.

• Survival of humans and animals is dependent on light, water, air and soil.

• Civilizations have crashed as a result of degraded soil.

• Good, productive soil is a basic human need.

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Why do we care about soil?

• “Man—despite his artistic pretensions, his sophistication, and his many accomplishments—owes his existence to a six-inch layer of topsoil and the fact that it rains.”

- Author unknown

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What does soil DO?

OK, so soil is important.

Why? What does soil actually DO?

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What does soil DO?

1. Soil serves as a natural medium for the growth of plants,

2. regulates and purifies water,

3. recycles organic wastes and nutrients,

4. provides habitat for soil organisms, and

5. serves as physical support for building and construction.

= Soil functions

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What does soil DO?

1. Soil serves as a natural medium for the growth of plants,

2. regulates and purifies water,

3. recycles organic wastes and nutrients,

4. provides habitat for soil organisms, and

5. serves as physical support for building and construction.

Soil health = soil’s capacity to function

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What is ‘soil?’

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Soil = solids + pore space

From Univ. of Massachusetts Extension Vegetable Program, Soil Basics, part I

Composition of typical soil, by volume Sand

Silt

Clay

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Organic matter

• Wide range of organic materials – Living organisms

• Plants, roots • Insects, nematodes • Fungi, bacteria

– Non-living OM, products of decomposition of living things • Continuously decomposed,

new compounds synthesized by other microorganisms

• Holds mineral particles together to form aggregates

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Pore space = air + water

• Air space provides gas exchange to organisms and plant roots

• Water is needed by plants and organisms

• Soil water also contains dissolved mineral compounds & nutrients needed by plants and organisms

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Soil Aggregation, Structure

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Soil Aggregation, Structure

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Soil Aggregation, Structure

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Soil Structure → Water Infiltration, Erosion Resistance

More storage Less storage

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Characteristics of healthy, well-functioning soils

• Good tilth = desirable combination of particle size, moisture content, aeration, water infiltration, drainage

• Sufficient nutrient content, not excessive

• Good, deep rooting depth

• Sufficient water storage and drainage

• Free from harmful toxins

• Plenty of active, beneficial organisms

• Few pathogenic, parasitic organisms

• Few weeds

• Resilient, able to resist degradation, erosion; recovers well from disturbances

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Agriculture can damage soil health

• Frequent, intense tillage

• Plant monocultures, loss of diversity

• Bare soil

• Heavy fertilizer/chemical use

• Heavy machinery traffic

→ Loss of soil structure → more runoff

→ Loss of soil through erosion

→ Loss of soil organic matter

→ Fewer, less active beneficial soil organisms

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Downward Spiral of Damage…

Intensive tillage, erosion, insufficient plant residues

Loss of SOM, compaction

Loss of aggregate structure

Compacted, crusty soil surface

Reduced infiltration, wind and water erosion

Loss of more SOM, topsoil, nutrients

Poor drainage, ponding, insufficient rooting depth

Fewer beneficial soil organisms, more pathogens

Crop yields decline

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Downward Spiral…

Reduced Soil Health

↓

Reduced Soil Function

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Compacted Soil Surface

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Water Erosion

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Wind erosion in NNY this winter

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So, how to minimize the damage?

1. Reduce frequency and intensity of tillage operations, compaction – No-till, strip-till, ridge-till, mulch-till, vertical-till

– All designed to disturb as little soil as possible

2. Increase organic matter inputs – Cover crops, manure, compost, plant residues

3. Vegetative plant cover all year – No bare soil, spring tillage

– Winter cover crops, leave plant residues

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So, how to minimize the damage?

4. Reduce compaction, field traffic

5. Crop rotation, perennials – Long rotations

6. Manage pests and nutrients efficiently – Test and monitor, apply only when needed at the right

time and place for optimal effect

Improvement takes time.

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Soil Health ↔ Soil Function

• How did we do?

–Understand the functions of soil and their dependence on soil composition and structure

– Explain to someone what soil structure is and how it drives healthy soil function

– Think of some ideas how you might preserve or improve your soil health

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Questions?