Soil Science - Study Mode

[#756] The cation exchange capacity is highest of
Correct Answer

(A) Vermicultil

Explanation

Solution: The cation exchange capacity is a measure of how many cations can be retained on soil particle surfaces. Negative charges on the surfaces of soil particles bind positively charged atoms or molecules (cations) but allow these to exchange with other positively charged particles in the surrounding soil water. CEC of vermiculite is 150, kaolinite is 3 - 15, chlorite is 10 - 40 and for montmorillonite CEC is 60 - 100.

[#757] The extent of Zn-deficient soils is approximately
Correct Answer

(C) 50%

Explanation

Solution: The extent of Zn-deficient soils is approximately 50%. About 50% of soil samples analyzed for available Zn were found deficient in India. Significant improvement in crop yield and quality through the balanced application of Zn has been reported across India. Adequate Zn application to crops is important for the food and nutritional security of India.

[#758] pH of Calcareous Soil is generally
Correct Answer

(D) 8 - 8.5

Explanation

Solution: Calcareous soil refers to calcisol with cemented carbonate layer near the surface in a desert environment. These often have more than 15% CaCO 3 in soil which are sparingly soluble salts that cause the soil to have high pH. The pH of calcareous soil is generally 8 - 8.5.

[#759] If fertiliser prices go up the optimum close should
Correct Answer

(A) Come down

Explanation

Solution: If fertilizer prices go up the optimum close should come down .

[#760] Olsen's method, which is used for phosphorus detection method used in soil is
Correct Answer

(A) All expected sodic soils

Explanation

Solution: The Olsen method is a chemical extractant (bicarbonate) that provides a reasonable estimate of the amount of plant-available P by measuring phosphate from the soil solution and exchange surfaces. This procedure is suitable for all expected sodic soils, calcareous, alkaline, neutral and slightly acidic soils containing CaPO 4 , since the calcium concentration in the solution is suppressed by the precipitation of CaCO 3 , increasing PO 4 concentration in the solution.