eChapters

The Kjeldahl method is mainly divided into three main steps. This method needs to be carried out in proper sequence. 

The statement is still valid as long as it is understood that in an aqueous solution the substances involved are subject to dissociation, which changes the ionization state of the substances. 

The lime requirement (LR) of an acid soil is the amount of lime needed to neutralize the acidity from an initial condition to some target soil pH, like 7.0. Different methods are used to calculate a LR for specific soils. Lime requirement tests will always recommend adding enough lime to neutralize all the acidity associated with soil pH, much of the salt-replaceable acidity, and some of the residual acidity.

In the detection of soil organic carbon a known weight of soil is heated with an excess volume of standard K2 Cr2 O7 in the presence of Con. H2 SO4 . The soil is slowly digested at the low temperature by the heat of dilution of H2 SO4 and the organic carbon in the soil is thus oxidized to CO2 . The highest temperature attained by the heat of dilution reaction produced with the addition of Con. H2 SO4 is approximately 12o C which is sufficient to oxidize the active forms of the soil organic carbon but not the more inert forms of carbon that may be present.

Electrical conductivity of the soil is the quantity of electricity in coulombs that passes per second per cm3 of the soil solution under an applied potential difference of 1 volt. It is written as EC in abbreviated form and is expressed in millimohs cm-1 or dS m-1 (deciSiemen m-1). Current flows in the soil solution due to presence of soluble salts like Cl- , SO2- 4 and NO3 - of Na+, K+ Ca++ and Mg++. These salts fully dissociate in water to their constituent cations and anions and the current is carried by those cations anions in the soil solution.

Atomic weight of an element is defined as the relative average weight of its atom as compared to the weight of an atom of C12 (stable isotope) taken as 12 on the a.m.u. (atomic mass unit) scale.

Determination of soil texture mainly depends on the complete dispersion of soil aggregates into their individual primary particles without triturating the particles themselves, accurate fractionation of the sample into various separates, sedimentation of different particles in the viscous medium as well as measurement of individual particle by the hydrometer.

The maximum water holding capacity is the amount of water, expressed as percentage on oven dry basis held by a soil when it is completely saturated with water. At this moisture content, all the pore spaces are completely filled with water.

Infiltration is the entry of a fluid from one medium into another. Soil water plays an important role in nature. The entry of rain or irrigation water into soil is called infiltration. Infiltration rate is defined as the amount of water entering into a soil per unit area per unit time under one atmospheric pressure. The infiltration rate depends upon initial moisture content of soil, condition of soil surface and permeability of various layers.

Field capacity may be defined as the amount of water held in soil after excess water has drained away and the rate of downward movement of water was materially decreased which usually taken place within two to three days after heavy rain or irrigation. In this condition water was moved out of the macropores and air has moved into take its place. 

The soil water plays an important role in the physical, chemical and biological activities taken place in the soil which directly or indirectly affects the crop growth. The water content of the soil can be measured by different methods. These methods are gravimetric method, neutron scattering method and electrical resistance method.

Primary particles tend to adhere under natural condition so as to form secondary unit called aggregates. It is very difficult to determine the diameter of the individual aggregated particle. So the mean weight diameter is calculated as a single value constant, which indicate the wetted average value for a group of aggregates.

Pore space or porosity : Porosity is an index of the relative pore volume in the soil or volume fraction of pores. Its value generally lies in the range of 0.3-0.36 (30-60%). Coarse textured soils tend to be less porus than fine textured soil, though the mean size of individual pores is greater in the former than in the latter. The total porosity, in any case, reveals nothing about the pore size distribution which itself is an important property.

Soil texture is the relative proportion of sand, silt and clay in soil by weight. As per the classification of the inorganic soil particle by the International Society of Soil Science, diameters of the sand, silt and clay particles vary from 2 to 0.02 mm, 0.02 to 0.002 mm and less than 0.002 mm, respectively. There are 3 broad textural groups i.e sand, loam and clay and each broad textural group is subdivided into different textural classes depending upon the proportion of sand, silt and clay.

Aim of the Experiment: The composite soil samples, collected, are air-dried and processed before analysis in the laboratory.

Soil testing identifies various constraints in soil that limit crop production. Fertilizer recommendation and soil management practices to be adopted are based on the soil test report. Soil testing starts with collection of soil samples from the field
and ends with interpretation of soil test results leading to necessary recommendations for increasing crop production.

Q. 1 In building material RCC stands for
(A) Revised cost calculation
(B) Revised construction cost
(C) Reinforced central construction
(D) Reinforced cement concrete

Q. 1 The question below consists of a pair of related words followed by four pairs of words. Select the pair that best expresses the relation in the original pair. 

Unemployed : Worker
(A) Fallow : land     (B) Unaware : sleeper
(C) Wit : jester        (D) Renovated : house

Q. 1 An ellipsoidal object has three axes measuring 40 cm, 20 cm and 20 cm respectively. The volume of the object is
(A) 4.23 liters       (B) 8.38 liters
(C) 12.63 liters     (D) 17.05 liters

Q. 1 Choose the most appropriate word from the options given below to complete the following sentence:
His rather casual remarks on politics ………. his lack of seriousness about the subject.
(A) Masked        (B) Belied
(C) Betrayed       (D) Suppressed

Q. 1 Froude number is the ratio between
(A) Inertia force to viscous forces (B) Inertia force to gravity force
(C) Inertia force to shear force      (D) Gravity force to inertia force

Q. 1 The amount of heat required to raise the temperature of 1gm milk by
one degree celsius in comparison to water is
(A) 85 %     (B) 93 %
(C) 107 %    (D) 100 %

Q. 1 Unit of refrigeration is:-
(A) Quintal    (B) Gram
(C) kg            (D) Ton

Q. 1 The high moisture grain should be kept in
(A) Air tight structure     (B) Aerated structure
(C) Pucca kothi             (D) Gunny bags in closed room

Q. 1 Which of the following is not a type of grinder ?
(A) Attrition mill      (B) Burr mill
(C) Hammer mill     (D) Solvent extraction mill

Q. 1 LSU dryer was developed at
(A) London State University       (B) Ludhiana State University
(C) Lucknow State University     (D) Lusiana State University

Q. 1 Psychrometric chart is a graphical representation of which properties
of air
(A) Chemical        (B) Aerodynamic
(C) Hygroscopic   (D) Thermodynamic

Q. 1 Fore sight is also known as
(A) Positive sight            (B) Minus sight
(C) Intermediate sight     (D) Vertical sight

Q. 1 Which type of gully is formed on flat land?
(A) U-shaped  (B) V-shaped
(C) L-shaped   (D) T-shaped

Q. 1 Which of the following is a correct match?
(A) Mole drain = pump drainage
(B) Vertical drainage = well drain age
(C) Pipe drain = well drainage
(D) Horizontal drain = bio-drainage

Q. 1 When flow parameters change with time but remain constant with space the flow is called as:-
(A) Unsteady uniform flow       (B) Steady uniform flow
(C) Steady non-uniform flow   (D) Unsteady non-uniform flow

Q. 1 A submersible pump may be
(A) Single stage pump       (B) Multi stage pump
(C) Centrifugal pump         (D) Both (A) and (B)

Q. 1 The development of a tube well should be started from :-
(A) Middle of screen      (B) Top of screen
(C) Bottom of screen     (D) Bottom of casing pipe

Q. 1 The Lysimeter is used to determine
(A) Sun shine hours   (B) Wind velocity
(C) Flow velocity        (D) Evapotranspiration

Q. 1 Hygrophilic soils are those
(A) Which attract water       (B) Which do not attract water
(C) Which transmit water    (D) Which produce water

Q. 1 Density of water is:-
(A) 1000 kg/m3    (B) 500 kg/m3
(C) 1500 kg/m3    (D) 2000 kg/m3

Q. 1 Annual depreciation of a machine is included in
(A) Fixed cost         (B) Variable cost
(C) Hiring cost         (D) None of the above

Q. 1 Weight of a manually operated chaff cutter’s fly wheel should not be
below than
(A) 24 kg      (B) 30 kg
(C) 32 kg      (D) 35 kg
(E) 27 kg

Q. 1 While operating a combine harvester, the grain not collected by the
machine is called
(A) Field loss         (B) Shattering loss
(C) Gathering loss (D) Reel loss

Q. 1 Operating speed of power sprayer varies from
(A) 2 - 5 km /hr          (B) 4.8 - 8 km /hr
(C) 10 - 20 km /hr      (D) 20 - 35 km /hr

Q. 1 If the forward speed of a tractor drawn seed drill is increased twice,
then the seed rate delivered will be
(A) Reduced to half            (B) Double
(C) Increased by four time (D) Remains the same

Q. 1 In agricultural tractors, the vibration level is in the range of .......... Hz.
(A) 0 – 2         (B) 2 - 8
(C) 8 – 20       (D) More than 20

Q. 1 A device which is used to store energy in hydraulic system is known as
(A) Motor             (B) Cylinder
(C) Accumulator  (D) Pump

Q. 1 Toe-in and toe-out are related with
(A) Front axle of tractor     (B) Rear axle of tractor
(C) Tractor steering           (D) Transmission system

Q. 1 Improper wheel balancing results in :-
(A) Excessive tyre pressure       (B) Excessive tyre speed
(C) Excessive tyre wear             (D) All above

Q. 1 In which of the following tractor components, the speed reduction takes place? 
(A) Gear box        (B) Differential
(C) Final drive       (D) All of the above

Q. 1 Which option about the statements made below is correct?
(1) The cooling system maintains engine temperature at 71 to 82ºC for petrol engines.
(2) The thermostat valve begins to open at about 60oC and opens widely at about 71ºC.
(A) Statement (1) is true, but statement (2) is false.
(B) Statement (2) is true, but statement (1) is false.
(C) Both statements (1) and (2) are true.
(D) Both Statements (1) and (2) are false.

A hunting governor is ……….
(A) Less sensitive       (B) More sensitive
(C) More stable           (D) None of these is correct

Direction of rotation can be reversed in
(A) 2- stroke engine           (B) 4- stroke engine
(C) Both (A) and (B)          (D) None of these

Sun’s radiation corresponding to that of a black body temperature is
about
(A) 50000 K           (B) 60000 K
(C) 70000 K           (D) 140000 K