Soil Science - Study Mode

[#311] Magnesium in octahedral sheet of clay mineral indicates
Correct Answer

(B) Trioctahedral

Explanation

Solution: Clay minerals are hydrous aluminum phyllosilicates, sometimes with variable amounts of iron, magnesium, alkali metals and alkaline earth. Clay minerals form in the presence of water, and have been important to life. Clay minerals are characterized by two-dimensional sheets of corner-sharing SiO 4 tetrahedra or AlO 4 octahedra. Magnesium is an octahedral sheet of clay mineral that indicates Trioctahedral .

[#312] Which one is right, according to population in soil?
Correct Answer

(A) Bacteria > actinomycetis > fungi

Explanation

Solution: The soil population consists of organisms constantly found in the soil (autochinous flora) and organisms present in the soil only in the form of spores (bacteria and fungi). According to the population in the soil, Bacteria are more in number than actinomycetes, which is more than fungi. The microbial population of the soil is determined by soil depth, organic matter, porosity, oxygen and carbon dioxide concentration and soil pH.

[#313] The amount of organic matter by weight in organic soil is
Correct Answer

(A) > 20%

Explanation

Solution: The amount of organic matter by weight in organic soil is more than 20%. Organic matter of soil is the organic component of the soil, consisting of plant and animal detritus at various stages of decomposition, cells and tissues of soil microbes and substances that soil microbes synthesize.

[#314] . . . . . . . . suggest that saltpeter (KNO 3 ), and not water, was the 'principle of vegetation'
Correct Answer

(A) J. R. Glauber

Explanation

Solution: J. R. Glauber (1604 - 1668), a German chemist, discovered that nitre or saltpeter is very important in plant nutrition. He has concluded saltpeter came from hydrolysis of urea to ammonium followed by nitrification to NO 3 which is then combined with K + . He showed that nitre is obtained from the cow dung and urine of animals in farmyard and it forms from the fodder formed from plants. The addition of these materials to soil increases the growth of plants. This is called Glauber's vegetation theory.

[#315] Which is the correct sequence of decreasing age of soil?
Correct Answer

(A) Ultisol, Alfisol, MoIlisol, Entisol

Explanation

Solution: The correct sequence of soils in case of decreasing age of soil, i.e. Ultisol, Altisol, Mollisol and Entisol. Ultisols mean last are strongly leached, acid forest soils with relatively low native fertility. Alfisols are clay-enriched subsoil and have relatively high native fertility. “Alf “ refers to aluminium (Al) and iron (Fe). Mollisols are the soils of grassland ecosystems. They are characterized by a thick, dark surface horizon. Entisols are soils of recent origin. It is defined as soils that do not show any profile development other than an A horizon.