Ahs 2204:Soil Chemistry Question Paper
Ahs 2204:Soil Chemistry
Course:Bachelor Of Horticulture
Institution: Meru University Of Science And Technology question papers
Exam Year:2013
QUESTION ONE – (30 MARKS)
a) Explain four (4) types of soil colloids. (8 Marks) b) Explain the difference between mineral colloids and the organic (humus) colloids. (6 Marks) c) Distinguish between a 1:1, 2:1 and 2:1:1 layer of silicate clays. (9 Marks) d) Differentiate between the following; i. Dioctahedral and Trioctahedral mineral. ii. Permanent charges and pH dependent charges. iii. Ectomycorrhizas and Arbutoid mycorrhizas. (7 Marks)
QUESTION TWO (20 MARKS)
a) Describe the characteristics of Kaolinite 1:1 type of silicate clays. (10 Marks) b) Explain the expanding nature f the smectite and vermiculite 2:1 type of silicate clays. (10 Marks)
QUESTION THREE (20 MARKS)
a) Explain the structural characteristics of humus and show the humus hydrophilic sites. (10 Marks) b) What do you understand by the following: i. Soil pH. ii. Isomorphous substitution iii. Humification
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iv. Mineralization v. Mineral mobilization. (10 Marks)
QUESTION FOUR (20 MARKS)
a) Explain what is cation exchange capacity (CEC) and explain how it is measured and it units of expression. (4 Marks) b) By using an equation, explain how calcium carbonate (CaCO3) liming reaction neutralizes soil acidity. (10 Marks) c) What are the commonly used liming materials? (6 Marks)
QUESTION FIVE (20 MARKS)
a) Distinguish between saline soils, sodic soils and saline-sodic soils. (6 Marks) b) Explain the agricultural practices that can be used to reduce and manage salted soils. (9 Marks) c) Explain the influence of micro-organisms in the soil rhizosphere. (5 Marks)
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