Soil Science MCQ Question and Answer | Agriculture MCQ Question

The water held with a water potential greater than $$\frac{1}{3}$$ bar is known as Gravitation water.
Gravitational water is the water that moves through the soil by the force of gravity and drains, the water moves in the larger pores of the soil and drains quickly because there is insufficient tension to hold the water against the force of gravity.

In India, Histosols are the soil order that has a negligible area. Histosol is soil consisting primarily of organic materials.
Organic soil material has an organic carbon content of 12 - 18% or more depending on the clay content of the soil. Histosols have very low bulk density and are poorly drained because the organic matter holds water very well. Histosols are also called Organosols.

Unconsolidated material overlying rocks is known as Regolith. Unconsolidated material is a sediment that is loosely arranged or unsatisfied, or whose particles are not cemented together, found either at the surface or depth.
It is a layer of broken soil material that forms the surface of the land and covers the bedrock nearly everywhere. Regolith is inorganic and lies like a blanket over unfragmented rock.

Zinc is the micronutrient that is usually a deficit in Indian soil. At present, about 48.1% of Indian soils are deficient in Diethylene-Triamine Pentaacetate (DTPA) extractable zinc.
Zinc is an important component of various enzymes that are responsible for driving many metabolic reactions in all crops.

The major organic cementing agent in soil aggregate formation is lipid.
Soil aggregates are clumps of soil particles that are held together by moist clay, organic matter (like roots), gums (From bacteria and fungi) and fungal hyphae.
Soil aggregates form through the combined action of cohesion and fragmentation processes.

Out of 17 essential nutrients of plants, some are macronutrients i.e. required in large amounts by plants whereas micronutrients are required in very fewer amounts.
Nitrogen, phosphorus and Potassium are the primary nutrients (Macronutrients) required by plants in higher quantities than other elements and without which the plants may not survive and grow. These nutrients boost the plant enzyme function, improve biochemical processes and help in plant cell growth.

Soils below the critical level of available nutrients are expected to respond to fertilizer. The nutrient concentration in the plant below which a yield response to added nutrient occurs. Critical levels or ranges vary among plants and nutrients but occur somewhere in the transition between nutrient deficiency and sufficiency.

A straight fertilizer has one major nutrient. Straight fertilizers are those which supply only one primary plant nutrient, namely nitrogen or phosphorus or potassium. Depending upon the nutrient availability they are further classified as nitrogenous, phosphatic and potassic fertilizers.

Non-essential mineral nutrients (elements) are required by certain plants, but not all, to perform their metabolic activities. The non-essential plant elements include hydrogen, oxygen and carbon.
Essential nutrients are those that cannot be synthesized by the human body, hence they need to be absorbed from outside whereas, non-essential nutrients are those that can be synthesized by internal processes.