Soil Science MCQ Question and Answer | Agriculture MCQ Question

A penetrometer is an instrument used to evaluate soil crust strength. It is the device to test the strength of any material. It is equipped with a known needle and mass to determine the hardness.
A penetrometer is also used to find the toughness of a leaf by measuring the force needed to punch a hole of a certain size through the leaf.

Permafrost is a layer where the soil temperature is always ≤ 0°C. It is defined as ground with a temperature that remains at or below freezing (0°C) for two or more consecutive years. It is a permanently frozen layer on or under the Earth’s surface. It consists of soil gravel and sand, usually bound together by ice.

Soil pH is a measure of the acidity or basicity of soil. Soil pH is a key characteristic that can be used to make informative analysis both qualitative and quantitatively regarding soil characteristics.
Soil pH is considered a master variable in the soils at affects many chemical processes. The optimum pH range for most plants is between 5.5 and 7.5.
It has been observed that soil pH increases in Winter.

Saline soils come under the Intrazonal soil group as a zonality concept.
Intrazonal soils have more or less well-defined soil profile characteristics that reflect the dominant influence o some resident factor of relief or parent material over the classic zonal effects of climate and vegetation.
Saline soil is one of the important intrazonal soil types, in saline soils, generally, no horizon differentiation and the whole profile looks more or less uniform.

Aspergillus niger is a haploid filamentous fungus that is used for waste management and biotransformation in addition to its industrial uses, such as the production of citric acid and extracellular enzymes.
The use of Aspergillus niger as a test organism for determining Magnesium, copper and Molybdenum in soils.

SSP is the most popular phosphatic fertilizer after DAP and it contains 3 major plant nutrients namely Phosphorus, Sulphur and Calcium along with traces of many micro-nutrients.
DAP is Diammonium phosphate, it is a series of water-soluble ammonium phosphate salts that can be produced when ammonia reacts with phosphoric acid.
SSP can have an edge in supplying Sulphur as it provides Sulphur also as a nutrient whereas DAP does not provide Sulphur to the soil thus it makes soil deficient in Sulphur.

Leaching is the process of loss of soluble substances and colloids from the top layer of soil by percolating precipitation.
In agriculture, leaching is the loss of water-soluble plant nutrients from the soil, due to rain and irrigation.
The leaching requirement of any soil can be estimated by the formula:
$${\text{LR}} = \frac{{{\text{E}}{{\text{C}}_{{\text{iw}}}}}}{{{\text{E}}{{\text{C}}_{{\text{dw}}}}}}$$

In the determination of moisture equivalent, the centrifugal force is used 1000 times of gravity.
Moisture equivalent is defined as the percentage of water that a soil can retain in opposition to a centrifugal force 1000 times that of gravity. It is measured by saturating a sample of soil 1 cm thick and subjecting it to a centrifugal force of 1000 times gravity for 3 min.

The subsoil is the layer of soil under the topsoil on the surface of the ground. It is composed of a variable mixture of small particles such as sand, silt and clay, but with a much lower percentage of organic matter and humus, and it has a small number of rocks that are smaller in size mixed with it.
The subsoil is also called a B horizon found just beneath A horizon or topsoil.

The most suitable form of Nitrogen for Flooded rice soil is Ammonium.
The absence of oxygen in the soil creates an anaerobic condition and thus promotes the growth of anaerobic microbes.
The flooded soil-rice plant ecosystem is extremely complex and final N budgets are the products of many N transformations modified by physical, chemical and biological agents, to a large extent controlled by oxygen fluxes.