Soil Science MCQ Question and Answer | Agriculture MCQ Question

Susceptibility to wind and water erosion is highest for Silt. As the size of silt is neither larger than sand nor it is tiny like clay, therefore silt-sized soil particles are washed away by water and blown away by the wind very easily in comparison to clay and sand.

Humic acid is a group of molecules that bind to, and help plant roots receive, water and nutrients. Humic acid increases nutrient uptake, drought tolerance, and seed germination. It also increases the microbial activity in the soil, making it an excellent root stimulator.
Humic acid can be isolated from the soil when soil is aromatic with high molecular weight.

The biological method for determining a deficiency of lime, P and K is Azotobacter Plague Test. The sensitiveness of the Azotobacter group of organisms to soil acidity and lack of available phosphate has been long recognized and has been the basis of microbiological tests to check soil deficiencies.

The particle size of coarse sand is about 0.2 - 2.0 mm (in diameter). Sand is the largest particle of the soil whereas clay is the finest one.
Soil texture is determined by the relative proportion of the three kinds of soil mineral particles, called soil separates i.e. sand, silt, and clay. These particles determine the properties like porosity, permeability, infiltration, shrink-swell rate, water holding capacity and susceptibility to erosion.

Sodic or alkali soils are clay soils with high pH, a poor soil structure and a low infiltration capacity. Alkali soils owe their unfavorable physio-chemical properties mainly to the dominating presence of sodium carbonate, which causes soil to dwell, and is difficult to settle.
Sodic soils are those which have an exchangeable sodium percentage (ESP) of more than 15. Excess to ESP has an adverse effect on the physical and nutritional properties of the soil.

A hydrometer method is used to determine the particle size distribution of fine-grained soils passing 75 µ sieve. The hydrometer measures the specific gravity of the soil suspension at the center of its bulb. It also measures soil bulk density.
A pycnometer is a small glass bottle of known volume for determining the relative density of liquids and solids by weighing. It helps in Particle analysis of soil.
A permeameter is a tool to measure soil moisture retention, saturated permeability, or K-factor of the soil samples.
A potometer is designed to measure water uptake in a leafy shoot. It cannot estimate soil moisture.

Soda feldspar is a crystalline mineral made up of mainly silica and alumina in combination with sodium and potassium oxides.
Albite is the Pure soda feldspar. The chemical formula of pure albite is NaAlSi₃O₈. It is a tectosilicate. Its colour is usually pure white and is a common constituent in felsic rocks.

The exchange acidity is the number of meq/100 grams of soil which consist of hydrogen, aluminum, and aluminum mono and di-hydroxide ions. The remainder of the cation change capacity would consist of exchangeable bases such as sodium, potassium, calcium and magnesium.
Exchange acidity is determined by Sokonov’s method.

The liquidity ratio is the ratio of the difference between natural water content, plastic limit and liquid limit. It is used for scaling the natural water content of a soil sample to the limits. It is used in the classification of the soil and it gives an idea about the plasticity of the soil.
The liquid ratio is used for soils where soil volume is not constant and for swelling soil.

Urea is a suitable fertilizer for foliar spray. It is designed to be applied directly to the leaves of a plant. As Urea is uncharged and highly soluble, also rapidly and efficiently absorbed by the leaves makes it suitable for foliar spray. After absorption, urea is changed into ammonia and carbon dioxide by a chemical called urease, found in the leaves of many plants.