[17agt12J vbm 29ram1433H]
@Apa itu soil horison? ==>http://soilscience.info/faqs/31-about-soil/113-what-is-a-soil-horizon-and-a-soil-profile
^lapisan tanah yg ketebalan bervariasi disetiap tempat
^ada 5 horison: O, A, E, B, C, and R.
The soil horizons, or natural layers of the soil, vary in thickness, depending upon location, and have somewhat irregular[tdk rata] boundaries. However, all the boundaries generally parallel the earth’s surface. The uppermost layers have been changed the most [sebgn terbesar/terbanyak], while the deepest layers are more similar to the original parent material. Exceptions to this vertical aging process occur when soil material is transported and deposited on the surface of previously formed soil profiles. Soil horizons can sometimes be easily identified and at other times be very gradual and faint. In older, well-developed soils, as many as five or six master horizons may be found in the soil profile. Younger, less-developed soils may have only two master horizons. Master horizons that may be found in soils include O, A, E, B, C, and R.
O horizon –When found, it is generally the uppermost layer of the soil and is predominantly made up of organic material. It consists of leaves, needles, twigs [ranting], mosses [lumut], lichens [lumut], and other accumulations of organic matter in various stages of decay. This horizon is typically found in wetlands and forested area, but is not present in cultivated fields due to soil mixing during cultivation.
The “O” stands for [singkatan dr] organic matter. It is a surface layer, dominated by the presence of large amounts of organic material in varying stages of decomposition [penguraian, pembusukan]. The O horizon should be considered distinct from the layer of leaf litter [sampah] covering many heavily vegetated areas, which contains no weathered mineral particles and is not part of the soil itself. O horizons may be divided into O1 and O2 categories, whereby O1 horizons contain decomposed matter whose origin can be spotted [terlihat] on sight (for instance, fragments of rotting/membusuk leaves), and O2 horizons containing only well-decomposed organic matter, the origin of which is not readily visible.
P horizon also heavily organic, but are distinct from O horizons in that they form under waterlogged conditions. The “P” designation comes from their common name, peats. They may be divided into P1 and P2 in the same way as O Horizons. This layer accumulates iron, clay, aluminium and organic compounds, a process referred to as illuviation
A horizon –Commonly called topsoil, this horizon is darker colored than lower horizons because it contains more organic matter, and it is often the most fertile layer of the soil. This is the layer that is plowed in cultivated fields and is where most root activity occurs. As rainwater percolates [meresap, merembes] downward through the A horizon it dissolves [melarutkan] minerals, and they are leached [meluluhkan] from the topsoil.
The A horizon is the top layer of the soil horizons or ‘topsoil’. This layer has a layer IS of dark decomposed organic materials, which is called “humus”.The technical definition of an A horizon may vary, but it is most commonly described in terms relative to deeper layers. “A” Horizons may be darker in color than deeper layers and contain more organic material, or they may be lighter but contain less clay or sesquioxides. The A is a surface horizon, and as such is also known as the zone in which most biological activity occurs. Soil organisms such as earthworms, potworms (enchytraeids), arthropods, nematodes, fungi, and many species of bacteria and archaea are concentrated here, often in close association with plant roots. Thus the A horizon may be referred to as the biomantle.However, since biological activity extends far deeper into the soil, it cannot be used as a chief distinguishing feature of an A horizon.
E horizon –This horizon is characterized by its light color or bleached [memutih] appearance. This is a zone which has been strongly leached. The main feature of this horizon is the loss of clay, iron, aluminum, humus, or some combination of these, which migrated downward as water passed through and a concentration of sand and silt particles. This horizon is commonly found in older, well-developed soils of woodlands. It is rarely found in cultivated areas, since plowing usually mixes this horizon with the A horizon.
B horizon –Commonly called subsoil, this layer is usually lighter in color than the A horizon due to its lower content of organic matter. It is the zone of accumulation for materials leached [melt, meluluhkan] from the A and E horizons. In older, well-developed soils, this horizon commonly has the highest clay content.
C horizon –This horizon is the transition layer between soil and parent material. It is less weathered than the upper horizons and contains partially disintegrated or weathered parent material from the underlying bedrock or transported to the area by glaciers, wind, or water.
The C horizon (parent rock) is simply named so it comes after A and B within the soil profile. This layer is little affected by soil forming processes (weathering), and the lack of pedological development is one of the defining attributes. The C Horizon may contain lumps or more likely large shelves of unweathered rock, rather than being made up solely of small fragments as in the solum. “Ghost” rock structure may be present within these horizons. The C horizon also contains parent material. It forms the framework of the soil. The A and B layers are formed by this layer. The C horizon forms as bed rock weathers and rock breaks up into particles.
R horizon –This horizon is the bedrock. As the bedrock weathers, it contributes parent material to the C horizon above. Bedrock can be within a few inches of the surface or many feet below the surface.
R horizons denote [menunjukan] the layer of partially weathered bedrock at the base of the soil profile. Unlike the above layers, R horizons largely comprise continuous masses (as opposed to boulders) of hard rock that cannot be excavated by hand. Soils formed in situ will exhibit strong similarities to this bedrock layer.
@Master horison –>http://en.wikipedia.org/wiki/Soil_horizon
O) Organic matter: Litter [sampah, kotoran] layer of plant residues in relatively undecomposed form.
A) Surface soil: Layer of mineral soil with most organic matter accumulation and soil life. This layer eluviates (is depleted of –>habis) iron, clay, aluminum, organic compounds, and other soluble [larut] constituents [unsur]. When eluviation [kekosongan] is pronounced, a lighter colored “E” subsurface soil horizon is apparent at the base of the “A” horizon. A-horizons may also be the result of a combination of soil bioturbation and surface processes that winnow [menampi, memisahkan] fine particles from biologically mounded [tumpukan] topsoil. In this case, the A-horizon is regarded as a “biomantle”.
B) Subsoil: This layer accumulates iron, clay, aluminum and organic compounds, a process referred to as illuviation.
The B horizon is commonly referred to as “subsoil”, and consists of mineral layers which may contain concentrations of clay or minerals such as iron or aluminium oxides or organic material moved there by leaching. Accordingly [krn itu], this layer is also known as the “illuviated” horizon or the “zone of accumulation”. In addition it is defined by having a distinctly different structure or consistency to the A horizon above and the horizons below. They may also have stronger colors (is higher chroma) than the A horizon.
As with the A horizon, the B horizon may be divided into B1, B2, and B3 types under the Australian system. B1 is a transitional horizon of the opposite nature to an A3 – dominated by the properties of the B horizons below it, but containing some A-horizon characteristics. B2 horizons have a concentration of clay, minerals, or organics and feature the strongest pedological development within the profile. B3 horizons are transitional between the overlying B layers and the material beneath it, whether C or D horizon.
The A3, B1, and B3 horizons are not tightly defined, and their use is generally at the discretion of the individual worker.
Plant roots penetrate through this layer, but it has very little humus. It is usually brownish or red because of the clay and iron oxides washed down from A horizon.
C) Parent rock: Layer of large unbroken rocks. This layer may accumulate the more soluble [larut] compounds.
R) bedrock: R horizons denote [merupakan] the layer of partially weathered bedrock at the base of the soil profile. Unlike the above layers, R horizons largely comprise continuous masses (as opposed to boulders) of hard rock that cannot be excavated by hand. Soils formed in situ will exhibit strong similarities to this bedrock layer.
[15agt13K vbm] Horison “O”
^ “O” singkatan dr ORGANIK tdd unsur2 organik al daun2, ranting dsb ttp bukan lap sampah yg mana tdk mengandung weathered mineral particles
^ Horison “O” tdd “O1” tdd unsur pelapukan + unsur asli & “O2” tdd unsur pelapukan sj
^ Horison “O” umum pd wetland & forested area & jarang pd cultivated field krn tanahx sering diolah
^ “P” artix PEAT
^ tdd organik jg tp bedo dg horison “O”
^ umum dijumapi dp waterlogged conditions
^ banyak mengandung iron, clay, aluminium and organic compounds, a process referred to as illuviation
^ disebut jg sbg TOPSOIL (=SURFACE SOIL) & warnax lebih gelap dp horison di bwhx krn tdd unsur ORGANIK jg. Lap ini disebut lap IS atau HUMUS. Tp ada jg yg warnax terang, ini krn sedikit unsur clayx
^ horison ini sering diolah krn merup lap yg subur
^ Aktivitas biologi umum terjd pd horison “A”
^ warnax lebih terang/keputihan
^ banyak tdd unsur hsl leached dr lap atas
^ dicirikan o/ the loss of clay, iron, aluminum, humus, or some combination of these
^ banyak dijumpai pd in older, well-developed soils of woodlands
^ TNHX PASIRAN
^ disebut SUBSOIL, warnax terang krn sedikit unsur oRGANIK
^ disebut jg zona akumulasi tdd clay or minerals such as iron or aluminium oxides or organic material moved there by leaching
^ In older, well-developed soils, this horizon commonly has the highest clay content.
^ PLANTS ROOT PENETRATE through this layer, but it has very little humus. It is usually brownish or red because of the clay and iron
oxides washed down from A horizon.
^ disebut sbg PARENT ROCKS
^ adl horison PERALIHAN dr SOIL ke PARENT MATERIAL
^ tdd unsur2 yg relatif blm melapuk (weathered) & masih ada batuan2 –> dg kata lain horison “C” tdd bedrock weathers and rock breaks up into particles
^ Parent rock: Layer of large unbroken rocks. This layer may accumulate the more soluble [larut] compounds.
^ disebut BEDROCK denote [merupakan] the layer of partially weathered bedrock
^ R horizons largely comprise continuous masses (as opposed to boulders) of hard rock that cannot be excavated by hand
[15-12-13M vbm] @WARNA TNH
Color in soils is due primarily to two factors, humus content & the chemical nature of the iron compounds present in the soil~~~A very high content of humus may mask [menyembunyikan] the color of the mineral matter to such an extent that the soil appears almost black regardless if [tdk peduli apakah] the color status of the iron compounds ~~~~Iron is an important color material because iron appears as a stain [noda] on the surfaces of mineral particles.About 5 percent or more of mineral soils is iron (1295)
There are various degrees of hydration, and the color varies between red and yellow. It is important to note that the yellow iron s in oxidized form as well as hydrated. This means that a supply of oxygen must be associated with moist conditions to cause yellow colors to form. Too much water & an absence of oxygen cause anaerobic microorganisms to reduce the ferric iron to ferrous form, & a gray color would be the result. The red color is associated with good aeration [penganginan, penjenuhan] & a generally lower
amount of water is present than is found in yellow materials. Soil colors are not limited to dark brown or
black with gray, red, or yellow or their intermediates. There are some soils with various other shades,
generally as a result of other minerals present in the parent materials (1295)
As colour of soil can be an indicator of certain physical and chemical characteristics, red in color is caused by the chemical nature of the iron compounds present mostly ferric oxide (hematite Fe2O3) and yellow in soil due to hydrated ferric oxide (2Fe2O3.3H2O) and gray indicates ferrous ixide (FeO) (1295)
[7mar14J vbm] Warna tanah ditentukan oleh 2 faktor yaitu oleh kandungan humusnya & kandungan komponen unsur/mineral besi. Jika tanah mempunyai kandungan unsur organik yang tinggi maka tanah tersebut cenderung berwarna hitam atau kehitaman & warna dari kandungan unsur besinya tidak terlihat.
Gradasi warna tnh berada diant warna merah & kuning. Warna tanah yang kuning atau kekuningan menandakan bhw tanah tsb bersifat lembab krn memp kandungan air yg cukup banyak.Tetapi jika kandungan airx terlalu banyak maka warna tnh cenderung abu2. Sebalikx, tanah yg berwarna merah atau kemerahan menandakan tanah tsb memp kandunga air yg sedikit (1295)
Warna tnh yg merah disebabkan oleh mineral ferric oxide (hematite Fe2O3); warna kuning krn hydrated ferric oxide (2Fe2O3.3H2O), & warna abu2 krn ferrous oxide (FeO)
[3-3-14Sn vbm] @PENGERTIAN HORISOn ~ ZONA PELAPUKAN
The effects of these soil forming factors (weathering) results in [mengakibatkan] the formation of layers within the soil from the
surface down to varying depths depending on the intensity [keadaan tingkatan] of the weathering. These layers are called horizons.The combination of these layers in a sequence from the surface of the soil down represents a soil profile.Road cuts & other man made excavations can expose soil profiles & serve as [berfungsi sbg] windows to the soil ~~ The layers in a soil profile are called horizons
[3-3-14Sn vbm] @GUNA OBSERVASI SOIL PROFILE
Observing how soils exposed in these excavations vary from place to place can add a fascinating [sangat menarik, yg mengasyikan] new dimension to our understanding of soils.Once you have learned to interpret the different horizons, soil profiles can warn
[mengingatkan] you about potential problems in using the land as well as tell you about the environment & history of the region. For example, soils developed under grasslands may have a very different soil profile than those developed under forestland.
[3-3-14Sn vbm] @FENOMENA PD PELAPUKAN BATUAN
Since the weathering of the soil profile starts at the earth’s surface & works [berjln, menjlkan] its way downward, the uppermost layers have been changed the most, while the deepest
layers are most similar to the original parent material
[7mar14J vbm] Akibat dari pelapukan thd batuan adalah terbentuknya banyak HORISON. Gabungan dr horison2 tsb membnt “soil profile”.
[3-3-14Sn vbm] @LAPISAN2 TANAH, TOPSOIL & SUBSOIL
The upper mineral horizons are designated as A horizons.Sometimes there is a layer of organic material covering the upper mineral horizon.This is designated as an O horizon.A horizons are darker colored than the lower horizons & contain more organic matter. Some constituents [unsur, komponen] such as oxides & clay have been moved downward from the A horizon by percolating [peresapan, merembes] rainwater.These often accumulate in the next layer called a B horizon.In some soil profiles there is a zone between the A & B horizons which has been strongly leached [menghancurkan lumat2 sampai hls] & is designated as an E horizon.The Unconsolidated [tdk kuat/bersatu]parent material is called the C horizon.C horizons are the least weathered of the unconsolidated material & are directly above the unweathered bedrock, the R horizon.The O & A horizons are commonly referred to as topsoil.The layers that underlie the topsoil are often referred to as subsoil.
[3-3-14Sn vbm] @KOMPOSISI TNH
Soils have four major components:(a) mineral matter, (b) organic matter, (c) air, & (d) water.
[3-3-14Sn vbm] @3 KELOMPOK UNSUR DLM TNH
Except for gravel & rocks that occur occasionally in soils, there are three fractions, sand, silt, & clay.
[3-3-14Sn vbm] @PASIR
Sand particles are large enough to be seen without the aid magnification & give soils a gritty feel.
[3-3-14Sn vbm] @SILT
Larger silt particles can barely be seen by the eye, & the smaller silt particles can be seen only with the aid of a microscope.Silt feels smooth within rubbed [gosokan] between the thumb & fingers & feels much like talcum powder or wheat flour.
[3-3-14Sn vbm] @CLAY
Clay includes the fraction smaller than silt & feels sticky [lengket] & plastic when wet, & harsh [keras, kasar] & hard when dry.Since clay includes all particles below the size of silt, this fraction contains the available plant nutrients not contained in the organic matter.
[3-3-14Sn vbm] @UNSUR ORGANIK TNH
The organic matter of soils is made up [tdd, disusun] of undecomposed & partially decomposed residues of plants & animals & the tissue of living & dead microorganisms. Organic matter contains appreciable [cukup besar, lumayan] quantities of nitrogen, phosphorus & sulfur which become available to higher plants as decomposition [penguraian] occurs.Furthermore, the decomposition of organic matter helps to produce substances [bahan] that make all of the plant nutrients more available. From a physical point of view, organic matter improves the aeration [penjenuhan] of soils, increases the water-holding capacity of the soil, & contributes to aggregate stability by supplying food for microorganisms whose function it is to produce chemicals which hold the soil particles together.
[3-3-14Sn vbm] @SOIL TEXTURE
Soil texture is determined by the relative proportions of sand, silt, and clay in the soil. (Fig 6). These proportions are placed into various classes to aid in communicating to others the significance of the various combinations. Each class name has max & min percentages of each fraction. A triangle showing the range in limits for each fraction & the various class names associated w/ these limits is called the Textural Triangle. (Fig 5).
[8mar14St vbm] @SOIL STRUCTURE
Structure refers to the arrangement [susunan] of soil particles. Soils made up of practically all sand or all silt do not show any appreciable [cukup besar] structural arrangement because of a lack of the binding [mengikat] properties provided by clay. A well-developed structure usually indicates the presence of clay. Soil structure is classified into various classes. There are three major classes & several sub-classes. They are as follows: Structureless which includes Single grain & Massive; w/ structure which includes Granular, Platy, Wedge, Blocky, Prismatic & Columnar; & Structure Destroyed [dihancurkan o/] which includes Puddled [menggenang, mengotori, meneruhkan].
Soil structure is of particular importance in the absorption of water & the circulation of air. A desirable structure should have a high proportion of medium-sized aggregates & an appreciable [cukup besar] number of large pores through which water & air can move. Structure of both the B horizon & the A horizon is very crucial [sangat penting] to proper [baik] drainage [saluran air], infiltration [perembesan] & productivity [kemampuan u/ menghslkan s/].In soils w/ poor structure, root penetration is limited thus reducing the plants access to water & nutrients. Structure of the A horizon has received a great deal of attention because of its relation to (a) seedbed [tmp pembibitan] preparation, (b) erosion potential, (c) aeration [penganginan, penjenuhan], (d) water infiltration, & (e) overall soil health.
There are three very important aspects of soil structure. They are (a) the arrangement into aggregates of a desirable shape & size, (b) the stability of the aggregate, & (c) the configuration [susunan, bnt] of the pores, that is, whether or not they are connected by channels or isolated. Aggregates that are stable in water permit a greater rate of absorption of water & greater resistance to erosion. Aggregates that are unstable in water tend to slake [mengurangi, memadamkan] and disperse [membubarkan, memencarkan].These aggregates, when exposed to raindrops, are particularly subject to dispersion & the resultant [yg dihslkan] crusting [mengeras] of soils.This crusting greatly affects seeding emergence, & increases runoff & erosion
The stability of aggregates is due to the kind of clay, the chemical elements associated w/ the clay, the nature of the products of decomposition [penguraian, pembusukan] or organic matter, & the nature of the microbial population. The expanding type of clay is more likely to produce unstable aggregates, other things being equal. An excess [kelebihan] of sodium associated w/ clays tends to cause dispersion [penyebaran, pengusiran, penguraian]. A high proportion of hydrogen &/or calcium is associated with aggregation [pengumpulan, kesatuan]. The mycelial growth of fungi appears to have a binding [mengikat] effect on soils.
Although kind of clay & amount of organic matter affects soil structure, there are other factors that also affect soil structure. The following have long been known to improve structure: freezing [pembekuan] & thawing [menjd cair], wetting & drying, action of burrowing insects & animals, & the growth of root systems of plants. All of these have a loosening [melonggarkan] effect on the soil, but it should be kept in mind that they have no part in aggregate [kumpulan, partikel] stability. The loosening of the soil is a necessary part of aggregate formation, not aggregate stability.
[8-3-14St vbm] @BULK DENSISTY
Bulk density refers to the weight of the oven-dry soil w/ its natural structural arrangement.The pore space is a part of the volume of soil measured for bulk density.Bulk density is
determined by dividing the weight of oven-dry soil in grams by its volume in cubic centimeters.The variation in bulk density is due largely to the difference in total pore space. Because finer textured soils have higher percentages of total pore space, it follows that finer textured soils have smaller bulk density
values. Obviously [tak pelak lg] then, compacted soils have lower percentages of total pore space & therefore, higher bulk densities. High &low bulk densities have great influences on engineering properties, water movement, rooting depth of plants, & many other physical limitations for soil interpretations.
[8mar14Stvbm] Struktur tnh itu berkenaan dg susunan partikel. Str tnh umumx tdd psr atau silt. Str tnh tdd 3 klas yaitu
1] Structureless which includes Single grain & Massive
2] structure which includes Granular, Platy, Wedge, Blocky, Prismatic & Columnar
3] Structure Destroyed which includes Puddled [menggenang, mengotori, meneruhkan]
Str tnh berkaitan dg kemampuan tnh u/ menyerap & sirkulasi air. Hor A & B adl hor yg penting dmn pd hor2 tsb (terutama A-hor) terjd perembesan air, tempat persemaian & tk kesuburan tnh
How was soil formed=> https://www.youtube.com/watch?v=Fx8r3o2gsLk [231015J vbm]
How To Differentiate & Identify Soil Horizons In The Field=> https://www.youtube.com/watch?v=ZlyDyQT6_WE [231015J vbm]
Soil Horizons=> https://www.youtube.com/watch?v=Zigo6T7fZ88 [231015J vbm]