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Soil Sciences




  • Soil science : It is a science, which deals with soils and natural resource on the surface of earth, including chemical, biological and fertility properties of soil and these properties in relation to their management for the growth of plants to clean the environment.

    Soil science : It is a science, which deals with soils and natural resource on the surface of earth, including chemical, biological and fertility properties of soil and these properties in relation to their management for the growth of plants to clean the environment.

    Earth : This term is used by engineers as a general name for unconsolidated masses that can be dug, moved or compacted and formed by equipment. It can come from shallow or deep layers of earth’s mantle.

    Land : It is a general term used to describe the non – water portion of earth usually in reference to a large surface area, but it is sometimes used synonymously for soil.

    Soil : The unconsolidated mineral and organic matter on the immediate surface of the ear that serves as a natural medium for the growth of the land plants.

    Soil chemistry : It deals with the study of chemical composition of soil and chemical reactions occurring in soil.

    Soil genesis : It is the study of mode of origin of soil with special regrernce to the processes or soil forming factors responsible for the development of the solum from the unconsolidated parent material.

    Soil morphology : It is the study of the soil including the texture, structure, consistency, color and other physical, chemical and biological properties of the various soil horizons that make up the soil profile.

    Soil classification : The systemic arrangement of soils into groups or categories on the basis of their characteristics .

    Soil conservation : The protection, improvement and use of soil according to principles that will ensure their highest economic and social benefits.

    Soil physics : It deals wit the physical processes of soil a s well as with the measurement, prediction control of the physical process take place in and through the soil.

    Soil fertility : It deals with the inherent capacity of a soil to supplement of the nutrient s in adequate amount and suitable proportion essential for plant growth.

    Soil biology : It is the branch of soil science concerned with soil inhabiting organisms and their functions and activities.

    Soil mineralogy : It deals with the study of structural chemistry of solid phase or it is the study of mineral occurring in the soil.

    Soil salinity : It deals with the study of salt – affected soil and their effect on plant growth.

    Soil survey : The systemic examination description classification and mapping of soils in an area soils are classified according to kind and intensity of field examination.

    Atmosphere : The atmosphere is a mixture of gases held to earth by gravity.

    Hydrosphere : It is the potion of the earth that includes oceans, seas, lakes and rivers together with water that has soaked into the grounds and occupies the opening in lithosphere.
    Lithosphere : It is the solid or rock portion of the earth.

    Mineral : Naturally occurring inorganic substance with characteristic internal structure and chemical composition having physical properties that are either uniform or variable within definite limits. All minerals except water and mercury are solids at normal temperature.

    Rock : Rock is an assemble of mineral grains.

    Cleavage and fracture :Cleavage is the tendency of the minerals to split along definite planes, where as fracture is the way of mineral breaks when it is not following a cleavage plane.

    Hardness : Hardness is the resistance of a mineral to stretching or abrasion.

    Luster : Luster is the general appearance of a mineral in reflected light.

    Streak : Streak is the color of the powdered mineral.

    Specific gravity : This is the weight of the mineral compared to the weight of an equal amount of water.

    Diaphaneity : It is the property of transmitting light.

    Tenacity : Tenacity is the behavior of mineral towards attempts to crush, cut , hammer, bend, tear or break it.

    Crystal : The definite shape of the mineral is called crystal.

    Primary minerals : Minerals that have not been altered chemical since deposition and crystallization from molten lava.

    Secondary minerals : Minerals resulting from the decomposition of a primary mineral or from the reprecipitation of the products of decomposition of primary minerals.

    Igneous rocks : Rocks formed by cooling and solidifying of extremely hot molten material. The word igneous meaning fire, which provides a clue to the origin of the rocks.

    Sedimentary rocks : Sedimentary rocks as the name implies, has formed from layers of accumulated sediment.

    Metamorphic rocks : Metamorphic rocks are formed when rocks already in existence are subjected to intensive heating, fluid impregnation of pressure.

    Weathering : All physical and chemical changes produced in rocks at or near the earth is surface, by atmospheric agents is weathering.

    Hydrolysis : It is a mineral weathering reaction that adds H+ ions to a mineral structure.

    Hydration : It is the addition of water molecules in chemical combination with a mineral to form hydrated compounds.

    Dissolution : When the solute is dissolved in the solvent, this process is called dissolution.

    Parent material : Unconsolidated products of weathering from which soil develop.

    Loess : Transportation of silty material through wind is called loess.

    Sand dunes :The coarse particle remains near the source and accumulate in the form of sand dunes.

    Adobe : It is similar to loess but calcareous in nature.

    Volcanic ash : Fine material of rock that is carried away wind from active volcanoes settles often in layers to become soil parent material. It is not important in our country but is found in Japan, Mexico etc.

    Soil formation : Soil formation means both the production of parent material by weathering process and the soil profile development.

    Process of soil formation : Addition, loess, transformations and translocations these four steps are known as process of soil formation.

    Topography : The earth’s surface contour is called its topography. It relates to the configuration of land surface and described in terms of difference in elevation slope and so on. Soil morphology is the visual observation of soil structure, shapes e.g. the arrangements of soil components in the soil profile. This can be studied in the field by naked eye with the aid of land lens and binocular stereoscope material with the electron microscopy. Soil profile : A vertical section of the soil through its various layers and extending into the C- horizon.

    O horizon : The o group is comprised of organic horizons that form above the mineral soil.

    H horizons : Horizons composed of mineral soil material, but strongly darkened by hum field organic matter intimately mixed with mineral fraction. The horizons import a darker colors that of lower horizon.

    E horizon : Mineral horizons from which silicate clay, iron, aluminum, or some combinations of these have an elevated leaving a usually light colored horizon. In which sand or silt sized quartz or other resistant mineral have been constructed.

    B-horizon : Horizons that form below and A, E or O horizon and show illuviation of materials has taken place from above and even from below.

    C-horizon : Mineral horizon or layers relatively unaffected by pedagogic processes and lacking properties of A, O, E or B-horizons. May be like or unlike the parent material of any overlying slum in the same soil.

    R layers : Layers composed of hard bed rocks, not practically dig able with a spade and shows little evidence of weathering.

    Horizons : Soil horizons are commonly considered to bee more or less parallel to the surface of the earth, but some horizons are irregular in shapes. Horizon is material that shows pedological organization.

    Pedon : A three dimensional body of soil with lateral diminish large enough to permit the study of horizon shapes and relations.

    Pedogenesis : Means mode of formation of a pedon, i.e “ a soil”. Pedogenic process these are the internal soil building processes “the combination or sequence of event for the rearrangement of matter that intimately affects the soil formation in which it oprates to give rise a particular type of morphology.

    Calcification : A process where by accumulation of CaCO3, to Cca horizon in soil profile, takes space.

    Decalcification : Reaction that remove CaCO3 from one or more soil horizons or eluviation of carbonates within a soil body.

    Pedzolization / silication : The chemical migration of Al and Fe and organic matter , resulting in the accumulation of silica in the layer eluviated or development of E horizon. Pedozilization is defined a stew process by which sesquioxides are Tran located in a soil profile.

    Desilication (laterization) : The chemical migration of silica out of the soil slum and thus the accumulation of sesquioxides in solum with or without formation of ironstone and concretions.

    Gleization : The reduction of iron under anaerobic ´waterlogged´ soil conditions with the production of bluish to greenish gray matrix colors, with or without yellowish brown, brown and black mottles and ferric and manganisgerous concretios.

    Salination : The accumulation of soluble salts such as So4 and Cl’s fo Ca, Mg, Na ad K resulting in slaty or salic horizon. desalination. The removal of soluble parts from salic or salty soul horizon.

    Sodication : It involves the accumulation of sodium ion son the exchange site sin a soil.

    Desodication : The removal of sodium ions and salts from nitric horizons.

    Soil texture : It refers to the relative portions of the three soil separates in a < 2 mm soil. Soil structure : The term structure relates to the clustering or arrangement of primary soil particles into secondary soil particles or units called peds or aggregates, which are separated from the each other by surfaced of weakness.

    Particle density : Particle density refers to the retio of the total and mass of the solid particle to their total volume excluding pore spaces between particles.

    Bulk density : It is defined as mass of dry soil solid per unit bulk volume. Bulk volume means volume of soil particles plus pore space.

    Pore space : The pre space of a soil is the proportions of soil bulk volume occupied by soil pores.

    Soil aeration : It is the process by which air in the soil is replaced by air from atmosphere.

    Soil water potential : The difference between free energy of soil water and that two pure, free water in a standard reference state is known as soil water potential.Gravitational water present in excess of field capacity or water held at potential greater than –33 kPa is called gravitational water.

    Field capacity : The content of water remaining in a soil two or three days after having been saturated with water and after the free water has been allowed to drain away is called field capacity.

    Permanent wilting percentage : It is the largest water content of soil at which plants growing in that soil will wilt and not recover when placed in a humid chamber. It is estimated at about – 1500 Kpa water potential or less.

    Soil consistency : It is a term used to describe the resistance of soil material to crushing and its ability to be molded or changed in shape.

    Ion exchange : It is the interchange of ions between colloids and solution phases and or between the solid phases if they are in close contact with each other.

    Cation exchange
    It is defined as the interchange between a cation in soil solution and another cation on the surface of any surface active soil particles such as clay colloid or organic colloid  between two colloids if they are in close contact with each other.
    Ctaion exchange capacity
    The total of exchangeable cations that a soil cans absorb at a specific pH. It is usually reported in comes or charge per kg dry soil;
    Anion exchange
    The positively charged sites may also be present on the soil colloid though in lesser number than the negative charge. Certain acid tropical soils contain colloids. with a net positive charge. These charge attract and exchange soluble anions just as negatively attract.
    Anion exchange capacity
    The sum total of exchangeable anions that a soil can adsorb is called anion exchange capacity.
    Soil pH
    Soil pH is the negative logarithm of the hydrogen ion activity in a soil or
    The hydrogen ion activity of a soil expressed by a set of –ve logarithmic values. The term pH is from the French pouvoir hdrgeheor” hydrogen power”.
    Soil reaction
    Soil reaction is an indication of the dire of acidity of alkaline of a soil and is determined by a glass or other suitable electrode or indicator  at a specific water content or soil water ratio
    Buffer solution
    Chemically a buffer solution is defined as one that represent a change in pH on addition of acid or alkali. In soils the clay and humic fractions act as a  buffer system.
    Soil buffer compounds.
    The solid and solution phase components of soils that resist marked pH changes in the soil solution are carbonates, phosphates, phyllosilicates, oxides and some organic materials.
    Humus
    Humus is colloidal, complex, and resistant to decomposition brown to black amorphous mixture of organic substances that result from microbial decomposition and synthesis and has physical and chemic al properties of great significance at soil and plant.
    Green manuring
    A growing  crop that is ploughed under and fixed with the soil to enrich it with organic matter is called green manure. The practice of turning into soil undecomposed green plant is called green manuring.
    FYM
    FYM consist of excreta of animals, litter, feed wastage, other plant debris and microorganism.
    Composting
    Composting is the microbial decomposition of piled organic materials into partially decomposed reduce, which are called composts or humus.
    Essential element
    For elements be considered essential plant nutrient, three criteria must be meet:
    1- A deficiency of the element makes it impossible for the plant to complete its vegetative or reproductive stage of its life.
    2- The deficiency symptoms of the element make it in question can be prevented or corrected only by supplying the element.
    3- The element is directly involved in the nutrition of the plant quite apart from its possible effect in correcting some microbiological or chemical condition dim soil or culture medium.

    SHORT QUESTIONS

    What is the atmosphere?
    The blanket of gases surrounding the earth that enables life to exist. There are different types of atmosphere.
    Troposphere…In, which we live.
    Stratosphere…it contains a layer of ozone.
    Mesosphere…it is a freezing sphere, which ranges from 50 to 80m above ground level.
    Thermosphere…it is hot sphere, which ranges from 80 – 480K.
    Exosphere…It is  outer atmosphere where space shuttle revolves.

    .What is difference between Evaporation and

    Condensation?
    Evaporation is a process by which liquid becomes gas and Condensation is a process by which gas becomes liquid.

    What is difference between Crust and Core?
    Crust is a thin, rocky outer most layer of the earth while Core is the inner most portion of earth. Average thickness of Crust is about 30 Km beneath the continent and about 10m beneath the oceans.
    What are Fossils?
    The ancient remains or traces of once living things, usually found preserved in rocks.
    What is difference between Magma and Lava?
    Magma is hot melted or molten rock that is formed mainly in the Earth’s upper mantle but also deep in crust and when it has reached the Earth’s surface through volcanoes called Lava.
    What is a Nutrient?
    A vital chemical substance that all living things need to
    live and grow.
    What is a Mineral?
    . Mineral is an inorganic crystalline substance, rocks are made up of minerals. Minerals are the most common solid materials found on the Earth.

    What are Igneous Rocks?
    A type of rock formed from magma that has cooled and
    hardened.
    What are Sedimentary Rocks?
    A type of rock that is formed by the pressing together of rock fragments or the remains of living things.
    sWhat are Metamorphic Rocks?
    A rock that has changed due to intense pressure or heat. Metamorphic rocks can form from Igneous Rocks, Sedimentary Rocks or other Metamorphic Rocks.
    What is eluviation?
    Movement of material out of a portion of a soil profile.
    What is illuviation?
    Movement of material into a portion of soil profile.
    What is erosion?
    Removal of material from the surface layer of a soil.
    What is cumulization?
    Eolian (movement through wind), hydrologic and human made additions of mineral particles to the surface of a soil solum.
    What is decomposition?
    Break down of mineral and organic materials with some chemical or biochemical changes
    What is the synthesis?
    The formation of new particles of mineral and organic
    species.
    What is solonization?
    The accumulation of sodium ions on exchange sites in a
    soil.
    What is podzolization?
    The chemical migration of aluminum and iron and organic matter into the eluviated soils
    What is melanization?
    The darkening of light colored unconsolidated, initial materials by admixture of organic matter.
    What is the term loosening?
    Increase in the volume of voids (pores) by activity of plants, animals, humans and by freezing , thawing , other physical processes and removal of material by leaching.

    What is the term hardening?
    Decrease in the volume of voids by collapse and compaction and by filling of some pores with the fine earth, carbonates, silica and other materials.
    What is soil?
    The un-consolidated mineral or organic upper part of earth’s crust that serve as a natural medium for the growth of land plants.
    Define the term soil fertility?
    The ability of a soil to supply the nutrients essential to
    plant growth.
    Define the term soil productivity?
    The capacity of a soil to produce a certain yield of crops with optimum management.
    What is soil structure ?
    The arrangement or grouping of soil particles into clumps
    or aggregates.
    What is soil texture?
    The relative proportion of soil particles(sand ,silt, clay) in
    the soil.
    What are alluvial soil?
    Soils which are formed by deposition  through water flood

    What are colluvial soils?
    Soils which are  deposited by gravity.
    What are loess?
    Soil particles which are deposited by wind. they are silt
    sized particles.
    What is the term mass flow?
    Movement of nutrients with the overall flow of water to
    plant roots.
    What are cutan?
    When clay particles are coated by some material called
    cutan.
    What are primary nutrients?
    Primary nutrients elements are carbon, hydrogen, oxygen, nitrogen, phosphorous and potassium.
    What are the secondary nutrients?
    These are calcium, magnesium, Sulphur.
    What are micronutrients?
    Those nutrients which are required in conc. > 100 ug/g of plant dry matter are known as micro-nutrients.
    How we can determine soil nutrient status and fertilizer requirement for crops?

    1. nutrient deficiency symptoms
    2. field experimentation
    3. Green house pot experiment.
    4. Soil testing.
    5. Plant analysis.

    What is the main cause of salinity and sodicity in Pakistan?
    It is reported that 70 – 75% of pumped water is brackish and their continuous use making the soil saline and sodic.
    It is reported that 3 million hectare have developed surface salinity or sodicity due to use of poor quality water.

    How many area of cultivated soils is under water logging in Pakistan?
    About 13% of the area in Pakistan has a high water table. Which enlarges to 26% after rain.
    What is the criteria for the fitness of irrigation water?
    We consider the water fit for irrigation which have total soluble salts less than 15 me/L, residual sodium carbonate less than 2.25 me/L and sodium adsorption ratio less than 10 (m mole/L)½.

    What is the major  role of organic matter in soil productivity?
    Soil organic matter serves not only as a reservoir of all the required plant nutrients but it also gives structure to the soil and provides energy for the microbial activity which is essential for the recycling of nutrients thus maintain the productivity of the soil.
    What are the major cations present in the soil?
    Major cations present in our soils are calcium, magnesium, potassium and sodium.
    Ca    >    Mg   >   K     >       Na
    (40 – 60 %)  (20 – 40 %)  (10 _ 20 %)
    What is salinization?
    The accumulation of soluble salts such as chlorides, sulphates and bicarbonates of Na, Ca, Mg and K in the soil.

    Fertilizer use in different countries (Kg/acre)

    Countries

    Nitrogen

    Phosphorous

    Potash

    Total

    Holland

    165

    28

    32

    225

    Korea

    93

    44

    52

    189

    China

    83

    31

    21

    135

    Japan

    53

    64

    44

    161

    India     (Punjab)

    54

    14

    0.8

    69

    Egypt

    105

    15

    3

    123

    Pakistan

    36

    9

    0.4

    46

    List of Nutrient removal by crops in Kg/acre (Production of one Ton)

    Crop

    Nitrogen

    Phosphorous

    Potash

    Wheat

    25

    9

    33

    Rice

    20

    11

    30

    Cotton

    62

    14

    60

    Sugarcane

    1.2

    0.5

    1.4

    Maize

    20

    8

    20

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