Soil Science MCQ Question and Answer | Agriculture MCQ Question

Percent pore space is defined by the porosity of a material possessing free space between the mineral grains expressed in percentage. It is proposed by Rebollo et al., 1996.
It depends on the size and sorting of the particles as a cubic or hexagonal package.
$$\% {\text{PS}} = 100 - \left( {\frac{{{{\text{D}}_{\text{b}}}}}{{{{\text{D}}_{\text{p}}}}} \times 100} \right)$$

Walkley & Black method is associated with soil organic Carbon. It helps in determining carbon.
This method quantifies the amount of oxidizable organic matter in which OM is oxidized with a known amount of chromate in the presence of Sulphuric acid. The remaining chromate is determined spectrophotometrically at 600 nm wavelength.

Andisols are derived from volcanic ejecta and are dominated by allophane.
Andisols are an essential tool for agriculture and can be used to cultivate sugarcane, tobacco, potatoes, tea, vegetables, wheat, rice and other crops. These soils also sustain fragile ecosystems in the Andes mountains from forests to paramos, helping to provide essential nutrients and regulate the water cycle.

In the acidulation reaction process, phosphoric acid is produced by reacting sulphuric acid with phosphate rock. This process is associated with nitrophosphate.
It should be mentioned that this reaction takes place in the presence of an excessively large amount of H₃PO₄.

Y-index is proved to be useful to assess the dominating type of clay mineral in soil proposed by Martin and Russell.
An index is defined as a numerical value describing the relative status of a population on a graduated scale with definite upper and lower limits, which permits and facilitates comparison with other groups classified by the same criteria & method.

DCD is the fertilizer that acts as a nitrification inhibitor and as a slow-release N source.
Dicyandiamide (DCD) is commonly used in fertilizer formulations as a nitrification inhibitor to slow the release of nitrogen into plant available forms that are also more prone to losses.
DCD works by blocking the active site, it also slows the conversion of ammonium to nitrate preventing the loss of nitrates.

A soil, which has pH varies between 7.5 to 8.5 and ESP less than 15 and total soluble salt content is more than 0.11, the soil is called Saline soil.
ESP is exchangeable sodium percentage and it measures the proportion of cation exchange sites occupied by sodium. Soils are considered sodic when the ESP is greater than 6 and highly sodic when greater than 15.

DTPA method is applied for testing of (Iron) Fe, (Zinc) Zn, (Copper) Cu and (Manganese) Mn.
DTPA (diethylene triamine penta acetic acid) is a method of extraction method of micronutrients. It is a non-equilibrium extraction for estimating the potential soil availability of the above minerals. It was developed by Soltanpour and Workman.

The hydraulic gradient is the driving force that causes groundwater to move in the direction of maximum decreasing total head. In soil science, it describes the effectiveness of the driving force behind water movement.
There is no unit of Hydraulic Gradient, it is unit less.

Pyrolusite is a manganese-containing mineral. It is a mineral consisting essentially of manganese dioxide (MnO₂) and is important as an ore of manganese. It is a black, amorphous appearing mineral, often with a granular, fibrous or columnar structure, sometimes forming Reni form crusts.