Soil Science MCQ Question and Answer | Agriculture MCQ Question

The C : N ratio of FYM is a ratio of the mass of carbon to the mass of nitrogen in a substance. The ratio of carbon and nitrogen in Farmyard Manure is 40 : 1.
The carbon to nitrogen ratio is significant in composting because microorganisms need a good balance of carbon and nitrogen to remain active. A high C/N ratio can lead to prolonged composting duration and low C/N ratios enhance nitrogen loss.

Phosphorus is one of the essential plant nutrients and is considered the energy currency of the plant.
It is the main component of the ATP (Adenosine triphosphate) system, the "energy currency" of plants and animals. Phosphate is an important part of the components of DNA and RNA.

Basic slag is the alkaline slag formed by the product of steel-making processes. It is generally rich in lime and sometimes also in phosphates and can be used as fertilizer.
Basic slag is a Double silicate and phosphate lime. It is used as a soil additive to render metals less soluble in contaminated soils by precipitation and adsorption on the surface of metal oxides.

Biotite is known as Black Mica. Biotite is a common group of phyllosilicate minerals within the mica group.
It was regarded as a mineral species by the International Mineralogical Association until 1998. Biotite has a highly perfect basal cleavage and consists of flexible sheets or lamellae, which easily flake off.

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 SiO₄ tetrahedra or AlO₄ octahedra.
Magnesium is an octahedral sheet of clay mineral that indicates Trioctahedral.

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.

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.

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 NO₃ 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.

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.

The oldest surviving long-term manurial trial in India is located at Coimbatore initiated in 1909.
The permanent Manurial Experiment (PME) was maintained at Tamil Nadu Agricultural University, Coimbatore. It is the oldest one having historical importance in India as it has completed 100 years of continuous experimentation.