Lecture 18: Soil and Water - 11/13 Flashcards

1
Q

What are the 5 components of soil?

A

Organic matter, mineral particles, water, gases, organisms

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2
Q

Composition of soil

A

1/2 mineral and organic matter
1/2 gases, water, living organisms

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3
Q

How is the mineral content of soil classified?

A

By diameter

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4
Q

How is soil TEXTURE determined?

A

By its particle-size distribution

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5
Q

What determines soil STRUCTURE?

A

How individual soil particles are aggregated

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6
Q

A Horizon

A

The topsoil; the zone of biological activity, leaching, and mineralization. Extends to ~65 cm

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7
Q

B Horizon

A

The middle layer, or subsoil; leachate accumulates here and there is moderate weathering. Extends from 65-90 cm

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8
Q

C Horizon

A

The bottom layer, or substratum; a zone of transition between the subsoil and parent material. Extends from 90 cm to bedrock

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9
Q

Parent rock/bedrock

A

The source of the soil’s mineral particles

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10
Q

Which horizons do plants root into?

A

Horizons A and B

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11
Q

O horizon

A

The layer above the A horizon comprised of organic matter in varying stages of decomposition

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12
Q

E horizon

A

An area that may develop between horizons A and B when there has been significant leaching, leaving a pale layer mostly composed of silicates

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13
Q

Order of horizons

A

OAEBC

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14
Q

USDA soil classification system

A

Order, suborder, great group, subgroup, family, series

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15
Q

Why is soil pH important?

A

Because it has a significant effect on nutrient availability

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16
Q

Cation-exchange capacity

A

Soil’s ability to retain and exchange cations

17
Q

What is the optimal pH range for most soils?

A

5.5-7.0 pH

18
Q

How can one determine fertilizer needs?

A

Through soil and tissue analysis or by observing deficiency symptoms

19
Q

What determine’s a soil’s water-holding capacity?

A

Its surface area

20
Q

What are the 3 types of soil water?

A

Gravitational water
Capillary water
Hygroscopic water

21
Q

What is the equation for available water?

A

AW = FC - PWP
AW: available water
FC: field capacity
PWP: permanent wilting point

22
Q

What is the most efficient watering method?

A

Drip irrigation

(hydroponics giving a devious sideye in the corner)