Soil Science - Study Mode
[#641] Soil with high mechanical impedance requires
Correct Answer
(D) Chisel plough
Explanation
Solution: Soil with high mechanical impedance requires Chisel Plough . A chisel plough is a common tool to get deep tillage with limited soil disruption. It helps to loosen and aerate the soil while leaving crop residue at top of the soil. Mechanical impedance is ubiquitous within the root environment. Penetration resistances of 0.5 - 1.0 MPa and greater are experienced in soil and reduce root elongation rates.
[#642] NH + 4 fixation takes place in
Correct Answer
(A) Vermiculite and illite
Explanation
Solution: Fixation of NH + 4 takes place in crystal lattices of different clay minerals like montmorillonite, illite and vermiculite. Illite typically weathers to vermiculite through the release of potassium ions from the interlayer. Fixation of ammonium ions by clay minerals is an alternate way of building the nitrogen pool in the soil to optimize N crop recovery and minimize losses.
[#643] Ammonium produced by urea can be absorbed by roots or it can
Correct Answer
(A) Change to nitrate
Explanation
Solution: Ammonium produced by urea can be absorbed by roots or it can change to nitrate. Plants absorb nitrogen in the form of ammonia and nitrate during the assimilation process. When nitrogen nutrients have served their purpose in plants and animals, it is covered back into ammonia and water-soluble ammonium salts by the process of ammonification. And further, bacteria will convert them back into nitrite and nitrate through the process of nitrification.
[#644] Dielectric constant of dry soil is
Correct Answer
(A) 3 - 6
Explanation
Solution: The dielectric constant is the ratio of the permittivity of a substance to the permittivity of free space. It is an expression of the extent to which a material concentrates electric flux and is the electrical equivalent of the relative magnetic permeability. The dielectric constant of dry soil varies between 3 - 6 depending on the texture of the soil.
[#645] Match the following columns: Column I (Particulars) Column II (Measuring instruments) a. Hygroscopic humidity 1. Irrometer b. Canopy temperature 2. Barometer c. Atmospheric pressure 3. Infra-red thermometer
Correct Answer
(B) a-1, b-3, c-2
Explanation
Solution: Irrometer measures the actual soil water tension and can be used to determine hygroscopic humidity. It indicates the effort required by root systems to extract water from the soil. The barometer is a scientific instrument used to measure atmospheric pressure. It works by balancing the weight of mercury in the glass tube against the atmospheric pressure. An infra-red thermometer is a thermometer which infers temperature which infers temperature from a portion of the thermal radiation emitted by the object being measured. It is used to measure Canopy Temperature.