Soil Science MCQ Question and Answer | Agriculture MCQ Question

The science dealing with the origin or formation of soil from the unconsolidated parent material with special reference to factors and process of soil formation is known as Soil genesis or pedogenesis. It is influenced by a few factors that are intertwined in the evolution of soil, these are parent material, climate, topography, organisms and time.

Red soil is dominant in Tamil Nadu. Red soil is formed in warm temperate and humid climates and comprises approximately 13% of the earth's soil. It contains thin organic and organic mineral layers of highly leached soil resting on a red layer of alluvium.
It contains large amounts of clay and is generally derived by weathering of metamorphic rock.

Steamed bone meal contains 30 - 35% P₂O₅.
Bone meal is primarily a source of phosphorus, which helps plants in bearing flowers and fruits. However, Steamed bone meal helps in the easier release of phosphorus in the soil. It is an excellent source of phosphorus, calcium and other important minerals including some nitrogen which aids in microbial activity to aid healthy top growth and stimulate root growth in plants.

In soil, the main process of heat transfer is Conduction.
Conduction is the mode of transfer of heat through matter without bulk motion of the matter. Moreover, it is the transfer of energy from the more energetic to less energetic particles of a substance due to interaction between the particles. Therefore in soils also the heat is transferred from one particle to another through the process of conduction.

Kaolinite is a clay mineral. It is a layered silicate mineral, with one tetrahedral sheet of silica linked through oxygen atoms to one octahedral sheet of alumina octahedra. It is described as a 1 : 1 or TO clay mineral because its crystals consist of stacked TO layers. Each TO layer consists of a tetrahedral sheet composed of silicon and oxygen ions bonded to an octahedral sheet composed of oxygen, aluminium and hydroxyl ions.
Two successive units of Kaolinite are connected by the means of an H-bond.

Crumby is the soil structure that is best for cultivation.
Soil structure is defined by the way individual particles of sand, silt and clay are assembled. It is determined by how individual soil granules clump, bind together and aggregate, resulting in the arrangement of soil pores between them.
There are various types of soil structures apart from crumby Platy, Prismatic, Columnar, Blocky, Granular, Wedge and Lenticular.

MP buffer was used for the determination of Lime requirement, having a pH of 7.5.
The primary purpose of Lime requirement Calculations (LBC) is to determine the lime requirement of soil to adjust it to the desired pH level.
It is calculated based on the three factors that are:
i) The initial pH of the soil
ii) The desired or target pH
iii) The soil’s LBC

The occurrence of quartz in high amounts makes a rock acidic. Rocks like granite, microgranite, and rhyolite rich in silica are acidic rocks and contain the minerals quartz and feldspar.
Acidic rocks refer to the chemical composition of igneous rocks that has 63% weight % SiO₂ content. It usually contains more than 20% of free quartz.

The fibrous Clay mineral is Attapulgite.
It is a magnesium aluminium phyllosilicate with the chemical formula (Mg, Al)₂Si₄O₁₀(OH)·4(H₂O) that occurs in a type of clay soil. It is a type of fuller’s earth. Attapulgite forms gel structures in fresh and saltwater by establishing a lattice structure of particles in fresh and saltwater by establishing a lattice structure of particles connected through hydrogen bonds.

Heterocysts are specialized N fixing structures found in BGA (Blue green algae).
A heterocyst is a differentiated cyanobacterial cell that carries out nitrogen fixation in aerobic conditions. It is formed during nitrogen starvation by some filamentous cyanobacteria. It works by differentiating highly specialized cells to provide fixed nitrogen to the vegetative cells in a filament.