Soil Science MCQ Question and Answer | Agriculture MCQ Question

Earthworm casts are the indurated soil material surrounding channels left in the soil by earthworms. The earthworm castings help increase soil’s water retention, improve soil aeration, anchor plant nutrients and boost soil fertility.
The casting of earthworms is rich in Calcium along with nitrogen, potassium, phosphorus and magnesium.

Soils that have detrimental levels of neutral soluble salts and a high proportion of sodium ions are classified as saline-sodic soils. Plant growth in these soils can be adversely affected by both excess salts and excess sodium levels.
For saline-sodic soils EC value is greater than 4, ESP is greater than 15, & pH values are greater than 8.5.

The purpling along the leaf edges are the characteristic deficiency symptom of Phosphorus. It mostly occurs on the underside of the older leaves due to the accumulation of the pigment, Anthocyanin.
Phosphorus is important for plants to promote photosynthesis, protein formation, seed germination, bloom stimulation and budding.

A soil with pH < 8.5, ESP < 15 and EC > 4 dSm-1 at 25°C is called Saline Soil.
Saline soil is referred to as one that inhibits the growth of most crops because of the higher concentration of neutral soluble salts in it.
ESP is Exchangeable Sodium Percentage, used to determine soil sodicity.
EC is the electrical conductivity, used to measure the salinity of the soil.

Entisols are soils of recent origin. It is defined as soils that do not show any profile development other than an A horizon.

Aridisols are Calcium containing soils of arid regions that exhibit subsurface horizon development.

Histosols are soils that are composed mainly of organic materials.

Vertisols are soils with a high content of clay minerals that shrink and swell as they change water content. It has no link with the word Pedalfor.

A flame photometer is used in the determination of Potassium.
The principle of flame Photometer is based on the measurement of the emitted light intensity when metal is introduced into the flame. The wavelength of the colour gives information about the element and the colour of the flame gives information about the amount of the element present in the sample.

The behavior of the plant about day length is termed Photoperiodism. It is the physiological reaction of organisms to the length of the night or a dark period.
Plant photoperiodism can be defined as the developmental responses of the plants to the relative lengths of light and dark periods.

Among the following, the correct sequence of biotic biopolymer degradation pathway is Fulvic acid - a humic acid - recalcitrant biopolymers- a humin acid.
Microbiological degradation of synthetic biopolymers takes place through the action of enzymes and acids and peroxides secretes from bacteria, fungi, yeast, etc. saprophytic enzymes play an active role in the decomposition process of humic substances in the soil.

Browning disease of rice is a Physiological disease. The physiological issues affect the toxicity level of iron elements which further causes browning disease of the rice.
Iron toxicity occurs usually due to submerged paddy fields with low pH, leading to dramatic increases in ferrous ion concentration, disrupting cell homeostasis and impairing growth and yield.

Limonite is an iron ore consisting of a mixture of hydrated iron oxide hydroxides in varying compositions. It is relatively dense with a specific gravity varying from 2.7 to 4.3. It is usually medium to dark yellowish-brown in colour. In its brown form, it is sometimes called brown haematite or brown iron ore.