Soil Science MCQ Question and Answer | Agriculture MCQ Question

The neutralizing value is a measure of the amount of acid a given weight of liming material will neutralize. Calcium carbonate is used as the reference and assigned a neutralizing value of 100 percent.
Calcium hydroxide has a neutralizing value (calcium carbonate equivalent) of 136%.

Humic acids are the organic substances that coagulate when the strong-base extract is acidified. It is a chemical produced by decaying plants. It is used as medicine for stimulating the immune system and treating the flu, avian flu and other viral infections.
A fulvic acid is a group of chemicals formed when plants and animals break down. It is found in the humus part of soil and peat.
Nitrogen content in Humic & fulvic acids is 1 - 4%. Humic acid contains more carbon and less hydrogen than does the animal and plant residues from which it has formed through extensive biological decomposition.

Potash is produced worldwide in amounts exceeding 90 million tonnes per year, with Canada being the largest producer of potash, mostly for fertilizer use followed by Russia and Belarus. The most significant reserve of Canada’s potash is located in the province of Saskatchewan and is mined by the Mosaic Company.

Potassium deficiency symptoms in corn appear first on the lower leaves because potassium is easily moved within the plant from older to younger leaves. Leaf symptoms are yellowing to necrosis of the outer leaf margins.
The critical value for K deficiency in maize is 1.0%. Potassium deficiency symptoms were observed when the tissue content was 2 - 3% of K and exchangeable K was less than 5 meq K/100g.

The microrelief of soils produced by expansion and contraction with changes in moisture is known as Gilgai microrelief. A gilgai is a small, ephemeral lake from a depression in the soil surface in expanding clay soils. Gilgai is found worldwide wherever cracking clay soils and pronounced wet and dry seasons are present. Gilgai is also called melonholes, crabholes, hogwallows or puff and shelf formations.

Phyllosilicate, are a compound with a structure in which silicate tetrahedrons each consisting of a central silicon atom surrounded by four oxygen at the corners of a tetrahedron are arranged in form of sheets or chains.
A chain like phyllosilicate is Palygorskite-sepiolite. Both of them have similar fibrous or lath-like morphologies, but palygorskite exhibits more structural diversity.

Iron is a micronutrient and is required by plants in small amounts. Most of the annual plants require fe on the order of 1 to 1.5 lb Fe per acre.
The deficiency of Iron starts when it is less than 55 ppm.
Iron deficiency starts with a yellowing of the leaves in between the dark green veins, giving the leaves a spidery look. After some time, the leaves become whitish and start to die back, eventually resulting in stunting and drying back of the entire plant.

Soils high in swelling clays that crack widely upon drying resulting in shrinking, shearing, and soil mass movement are characteristics of Vertisols.
The shrinking and selling of vertisols can damage buildings and roads, leading to extensive subsidence.
A vertisol is a soil type in which there is a high content of expansive clay minerals present and typically forms highly basic rocks.

A hygrometer is an instrument used in meteorological science to measure the relative humidity or amount of water vapour in the air.

The barometer is a scientific instrument used to measure atmospheric pressure.

The thermometer is a device that, measures temperature or a temperature gradient.

Rainguage is a meteorological instrument to measure the precipitating rain in a given amount of time per unit area.

Particle density is the density of the solid particles that collectively make up a soil sample. The value is commonly expressed in grams per cubic centimeter. The common range of all the soils is 2.55 to 2.70 grams per cubic meter.
The particle density of clay soil is 2.83 gm/cm³.