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Soil 211: Soil Chemistry Question Paper

Soil 211: Soil Chemistry

Course:Bachelor Of Science In Agriculture

Institution: Chuka University question papers

Exam Year:2013

CHUKA

UNIVERSITY

UNIVERSITY EXAMINATIONS
SECOND YEAR EXAMINATIONS FOR THE AWARD OF DEGREE OF
BACHELOR OF SCIENCE IN AGRICULTURE
SOIL 211: SOIL CHEMISTRY
STREAMS: BSC (AGRIC) Y2S1 TIME: 2 HOURS
DAY/DATE: THURSDAY 25/4/2013 8.30 AM – 10.30 AM
INSTRUCTIONS:

• Answer ALL Questions in Section ONE and TWO in Section TWO
• Section One is 30 Marks and Section Two 40 Marks

SECTION 1

1. (a) Distinguish between permanent and PH dependent charge. [2 Marks]

(b) Why is it recommended that ammonium or urea fertilizer be used for topdressing
in rice fields than nitrate source. [2 Marks]

2. Write short notes on;

(i) Chemical properties of organic mater. [3 Marks]

(ii) Anion Exchange [3 Marks]

3. (a) What are soil colloids? Briefly explain [3 Marks]

(b) Briefly explain what is the cation exchange capacity (CEC) of a soil.
[3 Marks]

(c) Assume a soil has 2.13 Ca2+, 0.53Mg2+, 0.13K+ and 0.1 Na+ meq/100gm. If the
total CEC is 3.25 meq/100gm of soil, calculate the percentage base saturation if the soil does not exhibit an anion exchange capacity. What is the proportion of the CEC occupied by acid cations. [4 Marks]

4. (a) Briefly discuss the effects of soil pH on soil biological activity and crop
production. [4 Marks]

(b) Briefly explain the pools of soil acidity. [6 Marks]

SECTION II

5. (a) State and briefly explain four factors affecting CEC of a soil. [8 Marks]

(b) Discuss the process of adsorption of cations and anions in soils. [12 Marks]

6. (a) Discuss the nutrient mobility within the soil and plant. [10 Marks]

(b) Briefly explain the relationships between pH and ion toxicity. [4 Marks]

(c) Using an equation of copper and magnesium distinguish between oxidation and
reduction reactions in crop production. Give an example of a reduction and an oxidation process in plant growth. [6 Marks]

7. (a) Discuss the factors that affect P-sorption in soils. [9 Marks]

(b) Briefly discuss aluminum toxicity in agricultural soils. [5 Marks]

(c) Explain how flooding and additions of organic matter helps in the management of
soil acidity. [6 Marks]

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Soil 211: Soil Chemistry Question Paper

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