Soil Science MCQ Question and Answer | Agriculture MCQ Question

Salt is present in soluble form in saline soils, as well as in irrigation water. The excess salt content hampers the crop yield, thus it is lowered by adding fertilizers and other nutrients. Salinity affects production in crops, pastures, and trees by interfering with nitrogen uptake, reducing growth, and stopping plant reproduction.
Soluble salt content which damages crop growth is 0.1 - 0.2%.

The ionic potential is the ratio of the electrical charge (z) to the radius (r) of an ion. This ratio is a measure of the charge density at the surface of the ion, usually the denser the charge, the stronger the bond formed by the ion with ions of opposite charge.
Out of the given options, Lithium has the highest ionic potential value. On moving down the group, the atomic number of alkali metals increases and their ionization potential value decreases.

The dry adiabatic lapse rate is the rate at which the temperature of a parcel of dry air decreases as the parcel is lifted in the atmosphere.
No heat is added or subtracted from the moving air parcel (adiabatic) and no moisture is condensing. The dry adiabatic lapse rate is 5.5°F per 1000 ft. or 9.8°C per km.

Baule unit is defined as the amount of nutrient when added results in moving 'Y' (yield) halfway closer to A (maximum potential yield).
One Baule unit will give 50% yield, the second Baule will give 50% of 50 i.e. 25% yield as such 2 baules will give 75% yield.
One Baule unit is 223 kg N, 45 kg P, 76 kg K.

C : N ratio is a ratio of the mass of carbon to the mass of nitrogen in a substance. The carbon to nitrogen ratio is significant in composting because microorganisms need a good balance of carbon and nitrogen to remain active. High C/N ratios can lead to prolonged composting duration and low C/N ratios enhance nitrogen loss.
C/N of a bacterial cell is 5 : 1, i.e. 5% of carbon with 1% nitrogen in each cell of bacteria.

Fungi imperfecti are the most frequent in soil. the fungi imperfecti or imperfect fungi are fungi that do not fit into the commonly established taxonomic classifications of fungi that are based on biological species concepts or morphological characteristics of sexual structures because their sexual form of reproduction has never been observed.
Eg: Deuteromycetes are one of the imperfect fungi.

Earthworms increase nutrient availability, better drainage, and more stable soil structure, these excrete wastes in form of casts, a type of soil aggregate.
The enhancement of the number of earthworms and their biomass consequently affect soil fertility. The total biomass of earthworms in soil ranges from 110 - 1100 kilometer per hector.

Igneous rocks are rocks formed from the crystallization of a liquid. It is divided into two categories, Intrusive crystallizing from magma beneath the earth's surface. And extrusive or volcanic rocks lava at the earth's surface.
In the case of igneous rock, if the cooling of magma is slow, then that rock’s texture will be coarse. If the magma cools slowly underneath the surface of the earth it forms granite with relatively large crystals. And if the magma cools rapidly on the surface of the earth the rock forms which is called lava.

Muriate of potash or potassium chloride is a red-white crystal containing 60% potassium oxide. It is extensively used for fertilizing pastures, sugar cane, fruit trees, vegetables and other field crops.
If 50 kg of K₂O/ha is needed to be supplied we need 83.3 kg of potash as 60% of 83.3 kg will be approximately 50, thus this much is needed.

Compost is a mix of decaying nutrient-rich soil with a medium density that is naturally made using oxygen, bacteria, water and organic materials. It takes around 6 months to be well decomposed.
The moisture content of well-decomposed compost is 15 - 25%. The organic material being decomposed has to be moist but not too wet.