Soil Science - Study Mode
[#291] The microrelief of soils produced by expansion and contraction with changes in moisture is known as
Correct Answer
(B) Gilgai
Explanation
Solution: The microrelief of soils produced by expansion and contraction with changes in moisture is known as Gilgai microrelief. A gilgai is a small, ephemeral lake from a depression in the soil surface in expanding clay soils. Gilgai is found worldwide wherever cracking clay soils and pronounced wet and dry seasons are present. Gilgai is also called melonholes, crabholes, hogwallows or puff and shelf formations.
[#292] Chain like Phyllosilicate is
Correct Answer
(C) Palygorskite-sepiolite
Explanation
Solution: Phyllosilicate, are a compound with a structure in which silicate tetrahedrons each consisting of a central silicon atom surrounded by four oxygen at the corners of a tetrahedron are arranged in form of sheets or chains. A chain like phyllosilicate is Palygorskite-sepiolite. Both of them have similar fibrous or lath-like morphologies, but palygorskite exhibits more structural diversity.
[#293] Iron deficiency starts when it is
Correct Answer
(A) < 55 ppm
Explanation
Solution: Iron is a micronutrient and is required by plants in small amounts. Most of the annual plants require fe on the order of 1 to 1.5 lb Fe per acre. The deficiency of Iron starts when it is less than 55 ppm. Iron deficiency starts with a yellowing of the leaves in between the dark green veins, giving the leaves a spidery look. After some time, the leaves become whitish and start to die back, eventually resulting in stunting and drying back of the entire plant.
[#294] Soils high in swelling clays which crack widely upon drying resulting in shrinking, shearing and soil mass movement are characteristics of
Correct Answer
(D) Vertisols
Explanation
Solution: Soils high in swelling clays that crack widely upon drying resulting in shrinking, shearing, and soil mass movement are characteristics of Vertisols . The shrinking and selling of vertisols can damage buildings and roads, leading to extensive subsidence. A vertisol is a soil type in which there is a high content of expansive clay minerals present and typically forms highly basic rocks.
[#295] Relative Humidity is measured by
Correct Answer
(D) Hygrometer
Explanation
Solution: A hygrometer is an instrument used in meteorological science to measure the relative humidity or amount of water vapour in the air. The barometer is a scientific instrument used to measure atmospheric pressure. The thermometer is a device that, measures temperature or a temperature gradient. Rainguage is a meteorological instrument to measure the precipitating rain in a given amount of time per unit area.