week 6 material

Question 1

What does Brown/black colours in upper

part of profile indicates?

Answer 1

high organic matter content

Question 2

What does Red indicate?

Answer 2

well drained conditions and oxidised iron oxides

Question 3

What does White, in subsurface layer,

indicate?

Answer 3

infertility due to

leaching

Question 4

What system is used to describe colour?

Answer 4

Munsell Colour System

Question 5

how many Hue charts are there in the Munsell Soli colour book?

Answer 5

7 Hue charts

Question 6

What are the different Hue symbols for colour?

Answer 6

R = Red
YR = Yellow-Red
Y = Yellow
G = Gley

Question 7

What are Aggregates?

Answer 7

cluster of soil particles

Question 8

What are Peds?

Answer 8

aggregates that occur naturally and persist

Question 9

What are Clods?

Answer 9

aggregates that occur artificially such as through tillage

Question 10

What is Soil texture?

Answer 10

size mix of the mineral particles

Question 11

What is Soil structure?

Answer 11

sizes, shapes and distribution of soil aggregates and soil pores

Question 12

What does a longer ribbon mean?

Answer 12

More clay

Question 13

How is Particle size determined?

Answer 13

Particle size is determined by laboratory methods

Question 14

What is clay defined as?

Answer 14

< 2 um

Question 15

What is Silt defined as?

Answer 15

2 - 20 um

Question 16

What is Sand defined as?

Answer 16

20 – 2000 um
• (fine) 20 - 200 um
• (coarse) 200 - 2,000 um

Question 17

What is Gravel defined as?

Answer 17

> 2000 mm (> 2 um; 1000 um = 1 mm)

Question 18

What are Soil Aggregates are held together by?

Answer 18

– Electrostatic forces (eg charge on clay minerals)
– Cementing substances like organic matter and hydroxides
– Fungal hyphae and fine plant roots

Question 19

What Bulk density?

Answer 19

Bulk density (Db) is an important mass measurement of soils
• Expressed as weight per volume ie. Mg/m3 or g/cm3

Question 20

What does Bulk density indicates?

Answer 20

suitability for root growth and

permeability

Question 21

How can bulk density be altered?

Answer 21

Can be altered by land management practices eg.compaction, tillage

Question 22

Soil organic matter description?

Answer 22

• Organic matter contains large quantities of plant nutrients
• Key component in improving soil quality and soil health
• Plays an important role in mediating both soil physical, chemical and biological activities

Question 23

how does Soil organic matter Improves soil structure?

Answer 23

increases aggregation
Increases soil water retention
Coarse organic matter particles loosen
soil, provide macropores and channels

Question 24

What is Soil health?

Answer 24

is the capacity of a soil to function within ecosystem and land use boundaries

Question 25

aspects of soil health?

Answer 25

– Sustain biological productivity – Maintain environmental quality – Promote plant, animal and human health