Soil Science MCQ Question and Answer | Agriculture MCQ Question

Grasslands are areas where the vegetation is dominated by grasses.
The spheroidal structure is dominant in grasslands, these have granular soil structure. The aggregates are 1 - 10 mm in diameter with rounded corners. This structure is usually seen in the A horizon or the layer of fine or medium-textured soils.

Pedon is the smallest unit or volume of soil that contains all the soil horizons of a particular soil type. Soils as unions of modules known as pedons. Soils are encountered on the landscape as groups of similar pedons, called polypedons, that contain sufficient area to qualify as a taxonomic unit.

The diagnostic surface horizons are called Epipedons. A horizon that forms at or near the surface and in which most of the rock structure has been destroyed. Epipedons are characterized by their colour, texture, structure and content of organic matter and certain plant nutrients.

A soil profile is a vertical section of soil, divided into several layers called horizons. The main horizons are A, B, C and D.
B horizon is commonly referred to as “Subsoil”. The B-horizon can accumulate minerals and organic matter that are migrating downwards from the A and E horizons. Because of this, it is also known as the illuviated or illuvial horizon.

Podsolization is a complex soil formation process by which dissolved organic matter like silica and ions of iron and aluminium, released through weathering of various minerals, form organo-mineral complexes and are moved from the upper parts of the soil profile and deposit in the deeper parts of soil.
The surface soils have relatively infertile and high in silica because of the process of podsolization.

Bulk density is defined as the dry weight of soil per unit volume of soil. Bulk density is dependent on soil organic matter, soil texture, the density of soil minerals (sand, silt and clay) and their packing arrangement. The bulk density of the clay soil is 1.10 grams per cubic centimetre.

Generally, soil contains 40 - 45 % inorganic matter, 5% organic matter, 25% water and 25% air. To sustain plant life, the proper mix of air, water, minerals and organic material is required.
Normally for agriculture purposes, Loamy-textured soils with equal distribution of sand, silt and clay are considered best.
However, the clay soils have great potential and are very fertile specifically with the presence of Chlorite and Illite.

Jean Baptiste Boussingault, was a French chemist who was considered the father of the field-plot technique. This technique is used to maintain a balance sheet that showed how much of the various plant nutrient elements came from the composition of his crops during various stages of growth came from rain, soil and air, analyzed.

When Fe contents in plants fall below or equal to 50 ppm, deficiency is likely to occur in plants.
Iron helps the plant move oxygen throughout the roots, leaves and other parts of the plant, producing the green colour that shows the good health status of the plant.

Reclamation disease is the disorder that affects crops grown on reclaimed land and is caused by the deficiency of trace elements like copper.
Reclamation disease due to copper deficiency occurs in plants grown on newly reclaimed is known as Ardisols. Aridisols are CaCo₃ - containing soils of arid regions that exhibit subsurface horizon development.