core soil properties #2 Soil mineralogy

Question 1

what are primary minerals

Answer 1

they persist with little change in composition and are found in sand and silt-sized fractions

Question 2

what are secondary minerals

Answer 2

they are formed by biochemical weathering of less resistant materials and are found in clay and fine silt-sized fractions
Ex. iron oxides, phyllosilicate clays

Question 3

where is calcium carbonates usually found

Answer 3

they are usually found in limestones and commonly found in grassland and agricultural soils of the Canadian prairies

Question 4

where is iron oxides usually found

Answer 4

in the red soils of Atlantic Canada

Question 5

how are iron oxides usually formed

Answer 5

they are usually formed by weathering of iron-containing primary minerals or precipitation of iron from the soil solution

Question 6

where can salt minerals high in sodium be found

Answer 6

they can be found in high concentrations where the underlying sedimentary rock consists of marine shale

shale soils can be found in certain areas of the Canadian prairies. high sodium salts limit crop production

Question 7

describe the secondary clay minerals and some of their characteristics

Answer 7

• appear flat and plate-like at very high magnification

- they possess varying amounts of negative charges

Question 8

why is negative charge in clay important

Answer 8

• gives extra water holding capacity
• acts as a storage mechanism for positive ions(cations) that are plant nutrients
• strong attraction of plant nutrients to clay particles strongly reduces the chance of nutrients being leached

Question 9

what are the different meanings for the word “clay”

Answer 9

• soil size
• soil texture class
• type of mineral

Question 10

what are common minerals found in soils

Answer 10

iron oxides
calcium carbonates
salt minerals high in sodium

Question 11

is clay a primary or secondary mineral

Answer 11

secondary