JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II Year PRINCIPLES OF SOIL SCIENCE AND AGRONOMY Previous Question Paper (December - 2017 - R13)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks and may have a, b, c as sub questions.
PART- A
Why bulk density of soil is less than particle density and calculate porosity of soil having bulk density of 1.5 Mg m-3 and particle density 2.5 Mg m-3.
Answer
Bulk density is lower than particle density because bulk density includes the volume of both soil solids and pore spaces, whereas particle density considers only the volume of the solid particles. Porosity is calculated as:
Substituting the values: [1 - (1.5 / 2.5)] × 100 = [1 - 0.6] × 100 = 40%.
Explain chemical weathering process of hydrolysis in minerals with example.
Answer
Hydrolysis is a chemical weathering process where water reacts with minerals to form new compounds, often resulting in the release of soluble cations. The hydrogen ions (H+) from water replace metal cations in the mineral structure. For example, the hydrolysis of orthoclase feldspar produces kaolinite clay:
State Poiseuille’s law with formula.
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Describe how soil colour indicates soil physical, chemical and biological properties of soil.
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Name / Mention what are the major problems in saline, saline – sodic and sodic soils with respect to plant growth and yield.
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Write / Give Arnon’s criteria of essentiality of nutrients.
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Define agriculture and agronomy. What is the scope of agronomy?
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Write a short note on depth and time of sowing of agricultural crops.
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Define a weed. List out the effects of weeds on crop production.
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Briefly explain the problems of crop production in dry farming.
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PART-B
What are soil moisture constants?
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Differentiate between Volcanic rock and Plutonic rocks.
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Define soil texture and explain Bouyoucos hydrometer method in determination of soil texture.
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List out different soil forming / pedogenic processes and write properties of laterite soils.
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Define colloid and explain different sources of origin of charge on colloids with examples.
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Describe mechanisms of gaseous exchange in soil.
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Enlist factors affecting soil temperature and brief account on management of soil temperature.
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Differentiate between saturated flow and unsaturated flow of water movement in soil.
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Define CEC, explain why cation exchange capacity is more important than AEC in agriculture.
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Differentiate between Kaolinite and montmorillonite minerals.
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Enlist different soil groups of India and explain any two soil groups.
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Define soil biology and explain role of soil organisms in agriculture.
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Explain the composition and structure of atmosphere with the help of a neat diagram.
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Write a short note on types of tillage and discuss in detail the effect of tillage on soil properties.
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Write the different methods of application of fertilizers.
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Explain different sowing methods.
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Explain the factors influencing soil erosion. What are the various agronomic measures for soil and water conservation?
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Define Organic Farming and Sustainable Agriculture. Explain the various principles involved in Organic Agriculture and its importance.
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Explain in detail the problems of crop production in dry land farming.
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