Soil Science MCQ Question and Answer | Agriculture MCQ Question

Chemical degradation of soil refers to the undesirable changes in soil chemical behavior so that the quality of soil declines due to human interventions. Soil degradation causes include agricultural, industrial and commercial pollution, loss of arable land due to urban expansion, overgrazing, unsustainable agricultural practices and long-term climatic changes.
Around 13.5 Mha of the area is under chemical degradation in India.

Soils are categorized as heavy soil or light soil in the aspect of impedance against mechanical force.
Light soil refers to soil high in sand relative to clay, whereas heavy soils are made up largely of clay.

The cryptogamic crust is the biological crust are microscopic non-vascular assemblages composed of blue-green algae, diatom, golden brown algae, lichens, mosses and a few xerophytic liverworts. It also covers the surface of soil between grasses, shrubs and flowering plants.
Thus, the cryptogamic crust is formed by Microbes.

The lime recommendation is made based on a 6 inch furrow slice. These are based on the pH goal.
The lime recommendation is defined as the amount of agricultural limestone or other basic material needed to increase the pH of the soil from an unacceptably acidic condition to a value that is considered optimum for the desired use of the soil.

Peat soil is generally characterized as Black, heavy and acidic soil.
It is an accumulation of partially decayed vegetation or organic matter. It is characterized by a high water table, absence of oxygen, reducing condition, low bulk density and bearing capacity, soft spongy substratum and low fertile soil.

Nitrogen and Sulphur are essential to plant nutrients and there is a strong relationship between S and N content in plants. The ratio of total N to total S and protein S determine the degree of availability of Sulphur in protein. Availability of proper nitrogen and Sulphur is important in the case of legumes, as it promotes nodulation in legumes. Therefore, the N/S ratio is wider in the case of legumes than in other crops.

Phosphorus is the element that is indirectly related to drought resistance. Drought resistance is the mechanism of minimum loss of yield in a water deficit environment relative to the maximum yield in a water constraint-free management of the crop.
Phosphorus is vital to plant growth and is found in every plant cell. It is involved in several key plant functions, including energy transfer, photosynthesis, the transformation of sugars and starches and nutrient movement within the plant.

Specific humidity is the mass of water vapour in a unit mass of moist air. Specific humidity is at a maximum in the tropics and declines as one moves poleward reaching minimum values in each polar region.
It can be calculated using the formula:
Specific humidity $${\bf{ = 6}}{\bf{.11 \times 1}}{{\bf{0}}^{\frac{{{\bf{7}}{\bf{.5\, \times \,dew\, point}}}}{{{\bf{237}}{\bf{.3\, + \,dew\, point}}}}}}$$
Its measuring unit is g/g or, kg/kg.

Boron is the element and is the only non-metal among the micronutrients of the plants. Boron plays a key role in a diverse range of plant functions including cell wall formation and stability, maintenance of structural and functional integrity of biological membranes, movement of sugar or energy into growing parts of plants, and pollination and seed set.

The correct soil order in the sequence of increasing age is: Entisol. Mollisol, Alfisol, Ultisol.

Entisols are known as the soil or recent origin. These are the most abundant soil order, occupying about 16% of the global ice-free land area.

Mollisols are the soils of grassland ecosystems. It has deep, high organic matter, nutrient-enriched surface soil and fertile soil order.

Alfisols are moderately leached soils that have relatively high native fertility. These are primarily found in temperate humid and sub-humid regions of the world.

Ultisols are the oldest soil order and are strongly leached, acid forest soils with relatively low native fertility.