Elements of Soil Science - Past / old Questions - 2064 Jestha, Bachelor in Agricultural Engineering, Tribhuvan University, Nepal, Third semester,
TRIBHUVAN UNIVERSITY
INSTITUTE OF ENGINEERING
Examination Control Division
2064 Jestha
Exam: Regular/Back
Level: BE
Programme: B. Agri.
Year / Part: II / I
Subject: Elements of Soil Science
Full Marks: 80
Pass Marks: 32
Time: 3 hrs.
✓ Candidates are required to give their answers in their own words as far as practicable.
✓ Attempt any Five questions.
✓ The figures in the margin indicate Full Marks.
✓ Assume suitable data if necessary.
1.
a) What are the different horizons of the soil profile? Explain each profile with their characteristics.
b) What is the characteristic of taxonomical classification of soil? How is soil classified based on this characteristic? [8]
2.
a) A soil pycnometer is designed on the principle of porosity tanks. Using this apparatus, the field porosity of a soil was determined to be 16.78%. The soil moisture content was 29.65% (dry basis), and its dry bulk density was 1.225 g/cc. If the volume of the measuring chamber was 728 cc, find the porosity of the dry soil (total porosity). [8]
b) Differentiate bulk density of soil from particle density. What factors are responsible for controlling bulk density of a mineral soil? [4+4]
3.
a) What are the drawbacks of poor aeration? Discuss the management practices you would adopt to improve soil aeration. [4+4]
b) What is the role of soil temperature in agricultural soils? Explain diurnal and seasonal variations in soil temperature. [4+4]
4.
a) What is meant by soil acidity and soil alkalinity? Which cations are responsible for soil acidity? How would you correct soil acidity? [8]
b) What are general plant nutrient deficiency symptoms? What are the functions of nitrogen in plant metabolism? Explain nitrification and denitrification. [4+4]
5.
a) How are layer silicate clays classified? Explain the different types of layer silicate clays. [4+4]
b) What are the different types of soil-forming rocks and minerals? How does weathering of these rocks and minerals occur? [8]
6.
Write short notes on (any four): [4×4]
a) Types of acidity
b) Soil color
c) Soil survey
d) FAO/UNESCO system of soil classification
e) Farmyard manure and green manuring
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