Soil Science - Study Mode
[#721] Which one of the following is not correctly matched
Correct Answer
(B) Micas : Iron and aluminium silicates
Explanation
Solution: Feldspar is a group of rock-forming aluminum tectosilicate minerals, containing sodium, calcium, potassium, or barium. Micas are a group of phyllosilicate minerals, not iron and aluminium silicates. Gibbsite is a hydrous oxide of aluminium. it is an important ore of aluminium. Goethite is hydrous iron oxide. It is a widespread soil mineral and a major component of many ores, sediments, and soils and it is one of the most thermodynamically stable iron oxides.
[#722] Cat clay minerals are
Correct Answer
(D) Both A and B
Explanation
Solution: Potentially acid sulphate soils are also known as cat clays. Cat clay minerals are Alunite and Jarosite. Cat clays are planted with rice so that the soil can be kept wet preventing oxidation. Subsurface drainage of these soils is normally not advisable. Alunite is hydrated aluminium potassium, sulphate mineral. It is usually mined for the manufacture of alum. Jarosite is a basic hydrous sulphate of potassium and ferric ion. This sulphate mineral is formed in ore deposits by the oxidation of iron sulphides.
[#723] The number 32 in 12-32-16 represents
Correct Answer
(B) P 2 O 5 content
Explanation
Solution: The number 32 in 12-32-16 represents P 2 O 5 content. This number represents the proportion of nutrients in complex fertilizer NPK which means Nitrogen is 12%, Phosphorous is 32% and potassium is 16%. NPK should be applied to the soil considering important factors such as placement, proportion and time of crop cycle.
[#724] Diagnosis and recommendation integrated system (DRIS) is applicable for
Correct Answer
(A) Long duration crops
Explanation
Solution: Diagnosis and recommendation integrated system (DRIS) is a mathematical technique to apply plant analysis information (Nutrient concentration) for diagnosing the most limiting nutrient in a production system. DRIS is a widely used statistical approach for interpretation of the plant tissue analysis data and diagnosing the plant nutrient needs much earlier than the reduction of crop yield with greater accuracy. It is applicable for long-duration crops.
[#725] Which of the following pairs is correctly matched?
Correct Answer
(B) Alkali soil - pH9
Explanation
Solution: Red soil is a type of soil that develops in warm, temperate and humid climates and comprises around 13% of the earth's soil. it is clayey in texture and rich in Iron oxide. Alkali soil is clay soil with high pH, greater than 8.5, a poor soil structure and a low infiltration capacity. Black soil is rich in lime, iron, magnesia, potash and alumina. The colour of the soil ranges from deep black to grey. Laterite is both soil and rock type rich in iron and aluminum and is commonly considered to have formed in hot and wet tropical areas. The pH of this soil is less than 7 and is acidic.