Soil Science MCQ Question and Answer | Agriculture MCQ Question

The equation introduced by Mitscherlich has been generally used to express nutrient-yield relationships as follows: $${\bf{y = A}}\left( {{\bf{1 - }}{{\bf{e}}^{{\bf{ - eb - ex}}}}} \right).$$
The classical Mitscherlich equation is based on Leibig’s Law of the Minimum and describes the yield response of a crop to an increase in the main factor that is limiting growth.
Mitscherlich's factor for phosphorus is 0.6.

When organic matter is greater than 1.5% in soil, rated as High.
Organic matter makes up just 2 - 10% of most soil's mass and has an important role in the physical, chemical and biological functions of agricultural soils. The portion made of fresh organic material and living organisms, as well as partially decomposed material that is slowly decomposing, is called active organic matter.

D. I. Arnor and Stout proposed the criteria of essentiality of plant nutrients in 1939. The elements that are considered essential elements in deficiency of which the plant must be unable to complete its life cycle.
There are 17 elements classified as essential elements and these are carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, Sulphur, calcium, magnesium, boron, chlorine, copper, iron, manganese, molybdenum, nickel and zinc.

The thermal conductivity of a material is a measure of its ability to conduct heat. Heat transfer occurs at a lower rate in materials of low thermal conductivity than in materials of high thermal conductivity.
The thermal conductivity of sand is highest in comparison to other soil particles given in the options. The thermal conductivity of dry coarse sand is 2.05 W/m/oC at steady state conditions.

Pumice is a rock having a specific gravity lower than water and sponge.
Specific gravity refers to the ratio of a solid or liquid to the density of water at 4 degrees Celcius.
Pumice is a pyroclastic igneous rock. It is extremely porous, with a foamy appearance. The specific gravity of pumice is found to be 0.95.

After submergence specific conductance of soil changes first increases then decreases. Submerged soils are soils that are saturated with water for a sufficiently long time in a year. Water fills the pore spaces and replaces the air.
Specific conductance refers to electrical conductivity i.e. water-quality property whose value is proportional to the collective concentration of ions in solution.

Phosphorite or rock phosphate is a non-detrital sedimentary rock that contains high amounts of phosphate minerals. The phosphate content of phosphorite varies from 4 - 20% phosphorous pentaoxide.
Rock phosphate is a natural source of phosphorous and is suitable fertilizer for soils that are Acidic as low pH helps to solubilize the rock phosphate and increases the available form of P to the plants.

Maize is a crop that can deplete maximum micro-nutrients from the soil.
Soil nutrient depletion can be attributed to insufficient fertilizer use, unbalanced fertilization, and nutrient depletion-induced soil fertility problems.
Growing corn uses a lot of water and fertilizer, especially nitrogen and phosphorus and some of these production techniques, are coupled with the effects of climate change.

The pH of cell sap is maintained by Calcium (Ca). It is related to differences in cation and anion absorption. The relative proportion of calcium ions to calcium also varies, with organic acids, such as malate and citrate, chelating calcium ions in xylem sap.
Cell sap is a fluid found in the vacuoles (small cavities) of the living cell. It contains variable amounts of food and waste materials, inorganic salts and nitrogenous compounds. The pH of cell sap is around 5.5 thus these are acidic.

Na₂CO₃ is the dominating salt among the given options in alkali soil. Alkali soils owe their unfavorable physio-chemical properties mainly to the dominating presence of sodium carbonate, which causes the soil to swell and difficult to clarify and settle.
Alkali soils are clay soils with high pH, a poor soil structure and a low infiltration capacity. They have a hard calcareous layer at 0.5 to 1 meter depth.