Dolomite powder is applied in some agricultural lands. The purpose of applying it is to
- A.increase the pH of the soil
- B.lower the pH of the soil
- C.increase the phosphorus content of the soil
- D.increase the nitrogen content of the soil
Correct answer
Explanation
The correct answer is A, increase the pH of the soil. Dolomite is a carbonate of calcium and magnesium, a base that neutralises soil acidity and so raises the pH.
Dolomite, CaMg(CO₃)₂, is a common liming material. In acidic soils, found in high-rainfall regions such as the North-East, Kerala and parts of Odisha, many nutrients become less available and aluminium can become toxic to roots. Spreading powdered lime or dolomite neutralises the excess acid and brings the pH towards neutral, around 6.5 to 7, where most crops grow best. Dolomite has the added benefit of supplying magnesium along with calcium.
Option B is wrong because lowering pH needs an acidifying material such as elemental sulphur, not a carbonate. Option C is wrong because dolomite contains no phosphorus; that comes from rock phosphate or superphosphate. Option D is wrong because it contains no nitrogen; that comes from urea, legumes or other nitrogen fertilisers.
Exam tip: acidic soil gets lime or dolomite to raise pH; alkaline or sodic soil gets gypsum.
Practice Questions
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- A.Galileo
- B.Martin Luther
- C.Johannes Kepler
- D.Copernicus
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- C.Urea is produced from digestion of starch.
- D.Urea is produced in lung and kidney.
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- A.Condenser-Objective lens-Eyepiece-Body tube
- B.Objective lens-Condenser-Body tube-Eyepiece
- C.Condenser-Objective lens-Body tube-Eyepiece
- D.Eyepiece-Objective lens-Body tube-Mirror
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- A.Haemoglobin present in RBC can carry only oxygen but not carbon dioxide.
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- C.Haemoglobin of RBC can carry only carbon dioxide.
- D.Haemoglobin is only used for blood clotting and not for carrying gases.
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- B.Histones are proteins that are present in nucleus in association with DNA.
- C.Histones are proteins associated with lipids in the cytosol.
- D.Histones are proteins associated with carbohydrates in the cytosol.
Show answer
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