Soil Science MCQ Question and Answer | Agriculture MCQ Question

Pedology is a discipline within soil science that focuses on understanding and characterizing soil formation, evolution, and the theoretical frameworks for modeling soil bodies in the context of the natural environment. It assumes the status of petrology, petrography and pedogenesis.
Petrology is the study of rocks and the processes that form and transform them.
Petrography is the process of petrology that focuses on detailed descriptions of rocks.
Pedogenesis is the study of the origin and formation of soil.

The soil organisms are most active at 24° - 35°C. It is the optimum temperature range required for the better functioning of microorganisms.
At very low temperatures they move to an inactive state and high temperatures may harm the structural damage to the microorganisms.
Soil temperature impacts the rate of nitrification. It also influences soil moisture content, aeration and the availability of plant nutrients.

Hydromorphic soils are characterized by the reduction of localized segregation of iron, owing to the temporary or permanent waterlogging of the soil pores which causes a lack of oxygen over a long period.
Hydromorphic soils are evolved by the process of Gleization. It is a typical pedogenic regime of soil that occurs in a moist or cool and cold climate. The pedogenic regime in the soil formation process results in the development of a Glei in the lower part of the soil profile above the parent material due to poor drainage conditions and where waterlogged conditions prevail and such soils are called hydromorphic soils.

If the particle density of soil is 2.6 and bulk density is 1.3 then the porosity percentage will be:
$$\eqalign{ & {\text{Soil porosity}} = \left( {1 - \frac{{{\text{Bulk Density}}}}{{{\text{Particle Density}}}}} \right) \times 100 \cr & = \left( {1 - \frac{{2.6}}{{1.3}}} \right) \times 100 \cr & = 0.5 \times 100 \cr & = 50\% \cr} $$

In plants, the common symptom caused by the deficiency of K, P, Ca and Mg is the Appearance of necrotic areas in the leaves.
Necrosis is the condition in plants when plants undergo abiotic stress they initiate rapid cell death with necrotic morphology. In simple words, it is the death of the tissue in a localized affected area.

Apatite is a group of minerals that mainly contains Phosphorus.
It is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of OH^-, fluoride, and chlorine ions respectively in the crystals.
The formula of the admixture of the three most common end members is Ca₁₀(PO₄)₆(OH, F, Cl)₂.
The primary use of apatite is as a source of phosphate in the manufacture of fertilizer and industrial uses.

Among the given options, Urea is the nitrogenous fertilizer for the amide group. It contains nitrogen in amide form but this form of nitrogen is swiftly converted by soil microorganisms into ammonical form and then into nitrate form.
Urea is a white crystalline solid containing 46% of nitrogen as an animal feed additive and fertilizer.

Humic acids are the organic substances that coagulate when the strong base extract is acidified.
Humic acids are organic molecules with complex structures and functions and variable properties.
Fractionation of humus sample is done to determine its solubility and the fractionated materials are likely to be heterogeneous and a large amount of sample would be necessary for their analysis. The ethanol soluble fraction of Humic acid is Hymatomelanic acid.

Soil microbial biomass is a measure of the mass of the living component of soil organic matter. The microbial biomass decomposes plant and animal residues and soil organic matter to release carbon dioxide and plant available nutrients.
The microbial biomass of the soil was determined by killing and lysing the soil microbes by fumigation with chloroform, irradiation with gamma rays or irradiation with microwaves.
Microbial biomass generally constitutes 0.01 - 0.4% of total soil mass.

Central soil salinity research institute is located at Karnal.
It is a premier research institute dedicated to pursuing interdisciplinary research on salinity or alkalinity management and the use of poor-quality irrigation waters in different agro-ecological zones of the country.
It works for the reclamation of rain-fed salt-affected soils, bio saline agro-forestry for fuel wood, bio-fuel, and energy plantation.