Soils

Front 1

Grid Survey Technique*

Back 1

Superimpose intersecting transects across survey area

Front 2

Free Survey Technique*

Back 2

Divide areas according to relative similarity (stratified sampling)

Front 3

Transect

Back 3

a straight line across the earth's surface, along which observations are made or measurements taken

Front 4

Statistical Mean*

Front 5

Median vs Mode

Back 5

middle object vs frequent

Front 6

Standard Deviation*

Back 6

How much data values vary from their average value

Front 7

Standard Error*

Back 7

How close sample mean is likely to be from the actual mean

Front 8

Bulk Density*

Back 8

The mass of dry soil per unit of bulk soil volume, including air space
BDu=TDW(g)/SV(cm3)

BDc=(TDW-CFW)g/(SV-DWV)cm3

Front 9

Porosity*

Back 9

[1-(BD/2.7)]x100

Front 10

What can lead to high and low soil bulk densities?

Back 10

High-compaction and location at lower soil depths tend to increase BD

Low-large amounts of organic matter tends to lower BD

Front 11

What bulk density values are associated with impairment of root growth?*

Back 11

Soils with BD>1.6g/cm3 restrict root growth

Front 12

What bulk density values reflect optimal air and water movement in soils?*

Back 12

Low BD<1.5g/cm3 unless waterlogged

Front 13

Three main bulk density sampling techniques

Back 13

Core Method, Excavation Method, Clod Method

Front 14

Core Method

Back 14

FT. double cylinder drop hammer sampler with core designed to remove cylindrical core of soil. Inner cylinder is driven into soil with blows.

Advantage-needing relatively simple equipment and obtaining an undisturbed core

Disadvantage-cores sampling area is small and can be stones and compression inside core that will throw off measurement

Front 15

Excavation Method

Back 15

Dig small hole, oven drying and weighing excavated soils. Line hole with plastic and fill with water to determine volume of excavation. Coarse fragments sieved out and BD is calculated.

Advantage-ability to obtain BD samples

Disadvantage-disturbs soils and carrying necessary water can be cumbersome

Front 16

Clod Method

Back 16

Large soil aggregate coated with water repellent substance, weighed suspended in air then in water to determine volume

Adds greater precision but requires more materials and equipment

Front 17

Three different forms of soil acidity

Back 17

Active, Exachangeable, Reserve

Front 18

How does Al contribute to soil acidity?*

Back 18

When Al is displaced from an exchange site into the soil solution, it hydrolyses, splitting water and releasing H+ ions into the soil solution

Front 19

How does soil acidity affect nutrient availability and levels of toxicity in soils?*

Back 19

pH 5.7-7.0=optimal plant growth

pH 5.6>=OM accumulation and less nutrient availability and concentrations of soluble Al, Fe, and Mn toxic to many plants

pH 7.0>= can reduce Fe availability

Front 20

Buffering Capacity (BC)*

Back 20

Soil’s ability to maintain a constant pH level during action on it by an acidifier or alkalescent agent.

Front 21

What kinds of soils have high BC?

Back 21

High clay or OM have high Cation Exchange Capacity

Front 22

Define three fine earth fraction particles sizes according to their average diameter ranges in the USDA system

Back 22

Sand 2mm-0.05mm

Silt 0.05mm-0.002mm

Clay <0.002mm

Front 23

Texture

Back 23

Percentages of sand, silt and clay sized mineral particles

Front 24

Horizons and Layers & USDA soil texture triangle

Back 24

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