eChapters

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