Soil Science - Study Mode
[#636] Single super phosphate contains
Correct Answer
(A) 16 - 20% P 2 O 5
Explanation
Solution: Single Superphosphate was the first commercial mineral fertilizer. It contains 3 major nutrients namely (16 - 20%) Phosphorus P 2 O 5 , 11% Sulphur and 21% Calcium along with traces of many micro-nutrients. The chemical formula of SSP is Ca(H 2 PO 4 ) 2 .2H 2 O (Monocalcium Phosphate Dihydrate).
[#637] Least resistant mineral to weathering is
Correct Answer
(B) Olivine
Explanation
Solution: Olivine is the least resistant mineral to weathering. Weathering is the deterioration of rocks, soils, minerals, etc. it is basically of two types, physical and chemical weathering. Olivine is a mixed crystal of Mg 2 SiO 4 and Fe 2 SiO 4 , in which the magnesium member is usually dominant. It is the major mineral in the mantle of the earth as these are not deteriorated by weathering.
[#638] Who developed the DTPA tests for available soil micronutrients
Correct Answer
(B) Lindsay W. L.
Explanation
Solution: The DTPA (diethylene triamine penta acetic acid) test is to test soil micronutrients and identifies near-neutral and calcareous soils with insufficient available Fe, Zn, Mn and Cu for maximum yields of crops. It draws on labile pools it was designed to extract and correlates well with plant micronutrient concentrations when the soil metal levels are neither too high nor too low. It was developed by Lindsay W. L. and Norvell, W. A. in 1978.
[#639] Urea of foliar spray should not contain biuret more than
Correct Answer
(B) 1.5%
Explanation
Solution: Urea of foliar spray should not contain biuret more than 1.5%. Fertilizer-grade urea contains the impurity Biuret which is toxic to the plant, especially when applied as a leaf dressing. Thus Biuret more than 1.5% can damage the root of the plant and also useful bacteria and chock the capillary of the root cell, Nitrogen carrying capacity will be reduced.
[#640] Silica-sesquioxide ratio is useful in the evaluation of soil in respect of
Correct Answer
(B) Iron and aluminum content
Explanation
Solution: Silica-sesquioxide ratio is useful in the evaluation of soil in respect of Iron and aluminum content . The usefulness of silica-sesquioxide ratios in the characterization of clay soil was studied by comparative analysis of primary and secondary minerals and clays isolated from the selected temperate region and tropical soils.