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BAHAN KAJIAN MK. DASAR ILMU TANAH TANAH VERTISOLS

BAHAN KAJIAN MK. DASAR ILMU TANAH TANAH VERTISOLS. TANAH VERTISOLS. RINGKASAN Vegetasi : lahan-berumput , pohon yg perakarannya dalam Iklim : variasi musiman hujan dan suhu ; beracam resim suhu tanah , kecuali pergelic Rezim lengas tanah : Rezim lengas-tanah erratik

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BAHAN KAJIAN MK. DASAR ILMU TANAH TANAH VERTISOLS

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  1. BAHAN KAJIAN MK. DASAR ILMU TANAH TANAH VERTISOLS

  2. TANAH VERTISOLS RINGKASAN Vegetasi: lahan-berumput, pohonygperakarannyadalam Iklim: variasimusimanhujandansuhu; beracamresimsuhutanah, kecualipergelic Rezimlengastanah: Rezimlengas-tanaherratik Ciritanah: kayaliat (dominaisliatmengembangtipe 2:1 type ---> montmorillonit, smectite), KTK tinggi, permeabilitasrendah, bidanggeser (slickensides) , mikro relief gilgai, warnagelapkhromarendah, BOT medium hinggarendah (0.5 - 3 %) Diagnostic horizons: cambic (argillic, natric) Epipedon: mollic Major processes: shrinking and swelling, pedoturbation Characteristics: stage of weathering relatively unadvanced or minimal, lack in horizon differentiation VERTISOLS: Tanah-tanahliatwarnagelap yang mengembang-mengkerut Beragambahaninduk, termasuk alluvial, colluvialdan deposit lacustrine Marl and other calcareaous rocks, limestone, shales, igneous, metamorphic and volcanic rocks of basic nature Unconsolidated sediments which are dominantely basic in character and low in quartz The parent material although variable in origin, are rich in feldspars and ferro-magnesian minerals and yield clay residues on weathering Vertisols may develop in situ from the parent materials. The smectites in these soils could be derived from the original rock or form as a result of neogenesis or transformations from primary minerals. Ciriutama: kayaliat (dominasiliatmengembangtipe 2:1 -> montmorillonite, smectite) Diunduhdari: ………….. 25/2/2013

  3. TANAH VERTISOLS KONDISI LINGKUNGAN IKLIM: Vertisolsditemukandihampirsetiap zone iklimutama. Di Australia , Vertisolsberkembangdidaerah-daerahdenganrezim air aridik, danadajugadi zone UstikdanXerik. Generally, the seasonal variations in precipitation and temperature, which favor the formation of smectitic clays as well as provide many of the physical attributes of these soils, would be considered as prerequisites for the formation of Vertisols. The variation in climatic conditions result in weathering of primary and secondary minerals during wet season, but encourage the accumulation of basic cations in the dry season. Areas where Vertisols are found are characterized by a period when the potential evapotranspiration exceeds precipitation (fry period). During periods with sufficient moisture deficit cracking occurs, although the intensity in cold temperature regions, is much lower than in the warmer regions. Umumnya, curahhujantinggimenghasilkanretakan-retakan yang intensif, peningkatankandungan BOT, danpeningkatanpencuciankarbonatdangaram-garam. Diunduhdari: ………….. 25/2/2013

  4. TANAH VERTISOLS KONDISI LINGKUNGAN VEGETASI: Vegetasialamiah yang berasisoasidneganordotanahinisangatberagam. Tipe-tipevegetasialamiah, hinggabatastertentu, dibatasiolehsifat-sifattanah, sepertikandunganliatygtinggi, sifatmengembang-mengkerut, danstrukturtanah. Sifat-sifattanahdaniklimmembatasitipe-tipevegetasisepertirumputdanpohon yang tumbuhnyalambatdnaperakarannyadalam (mis. Acacia). The main features of the natural vegetation in these soils are tolerance to drought, as well as development of deep roots to overcome root damage by a consequence of the annual cracking. Most Vertisols have has grassland or savanna vegetation as the native vegetation, but some had formed under forest. Present use of Vertisols comprise wheat, rice, cotton, and sorghum, pastureland in the the south of the United States. Vertisols in India are used for grain legume, oil seed crops, and cotton cultivated in a ridge and furrow system. In Australia most Vertisols are used for grazing by sheep and cattle or dry land agriculture. Large areas of Vertisols in Africa are largely un-utilized except for extensive grazing. Diunduhdari: ………….. 25/2/2013

  5. TANAH VERTISOLS KONDISI RELIEF Adaduasekala yang berbeda, yaitu (i) makro, dan (ii) mikro. Relief Makro : Vertisolsumumnyaditemukandidaerah-daerahdengankemiringantidaklebihdari 5 %, karenaakanterjadierositanah yang intensif.. Sering kali daerah yang datarkekuranganjaringan drainage, infiltration lambat, mengakibatkangenangan air dipermukaan. Micro relief: Gilgai-relief. The development of gilgai-relief is due to shrinking and swelling of Vertisols and soil movement, i.e., the soil mass cannot re-occupy the original volume since surficial material has fallen into the cracks during dry season. As such, part of the soil mass is forced upwards forming the mounds (or knolls). The formation of a mound provides a locally preferred site for the further release of pressure, thereby perpetuating the formation of other mounds and depressions in an area. Diunduhdari: ………….. 25/2/2013

  6. TANAH VERTISOLS BAHAN INDUK TANAH Vertisolsberkembangdariberagambahaninduk, termasuk alluvial, colluvialdan deposit lacustrine, batuan marl danbatuanberkapurlainnya, limestone, shales, igneous, batuanmetamorfdanbatuanvulkanik yang bersifat basis (alkalis). Bahanindukvertisols ini dapat berasal dari allochtonous ataur autochthonous. Dalam banyak kasus, bahan induk tanah merupakan endapan muda dan pembentukan tanah masih pada fase awal. Vertisols may develop in situ from the parent materials. The smectites (clay minerals) in these soils could be derived from the original rock or form as a result of neogenesis or transformations from primary minerals. A high pH and high potentials of Si as well as Mg smectites develop, a process which is also favored by poor drainage conditions. Calcareous parent material or unconsolidated sediments which are dominantely basic in character and low in quartz favor the formation of Vertisols. Anah-tanah ini berkembang di daerah dataran dengan bahan induk liat berkapur atau calcareous atau residu pelapukan dari batuan sedimen yang lunak dan berkapur. Vertisols di Australia berkembang dari bahan induk batuan basalt, di India vertisols berkembang dari bahan induk gneisses daan sandstones. The parent material although variable in origin, are rich in feldspars and ferro-magnesian minerals and yield clay residues on weathering. Where parent materials are not basic, alkaline earth elements can be added by seepage or by flood water. Diunduhdari: ………….. 25/2/2013

  7. TANAH VERTISOLS KONDISI LINGKUNGAN Waktu - Time: KebanyakanVertisolsberkembangpadalanskapmuda, tetapijugaditemukanpadapermukaangeomorfiktua. It is believed that the stage of weathering in Vertisols is relatively unadvanced or minimal. Sketch showing the kinematics of mass movement in Vertisols that result in gilgaimicrorelief (after Beinroth, 1965) Diunduhdari: http://www.fao.org/docrep/003/Y1899E/y1899e06.htm………….. 1/3/2013

  8. TANAH VERTISOLS Mikro-relief Gilgai. Diunduhdari: http://www.fao.org/wairdocs/ILRI/x5493E/x5493e05.htm ………….. 1/3/2013

  9. TANAH VERTISOLS Microphological differentiation of a sequence of soils (generalised). Diunduhdari: http://www.fao.org/wairdocs/ILRI/x5493E/x5493e05.htm ………….. 1/3/2013

  10. TANAH VERTISOLS PROSES GENESIS TANAH Vertisols form under multiple genetic pathways which are complex. In general, soil forming processes that lead to the formation of Vertisols are those which control the formation and stability of smectites in the soil. However, subsidiary processes, such as fluctuations in the moisture status, accumulation of organic matter, carbonates, gypsum or soluble salts and acidification processes through leaching, result in the differences within the Vertisols. The development of Vertisols requires conditions that ensure the formation and preservation of smectites. These clay minerals may form either in situ through the weathering and development of a solum (autochtonousVertisols) or from a sediment which is composed of materials that can produce vertic properties (allochtonousVertisols). The latter is geographically more extensive and occupies the lower parts of the landscape. The development of smectitic clays is favored by a high pH with sufficient Ca2+ and Mg2+ in the soil system. The presence of a relatively impermeable layer at some depth within the soil prevents the leaching of the various components needed to form smectites. Diunduhdari: ………….. 25/2/2013

  11. TANAH VERTISOLS PROSES GENESIS TANAH Pengkerutandanpemuaianmenyebabkanterjadinya “shearing” sehinggamenghasilkanpembentukan “slickensides”. Prosesinidisebabkanolehadanya mineral liat “smectitic” danalterasimusimbasahdanmusimkering. Akibatdariprosesini, Vertisolsmembentukretakan-retakan yang dalamdanlebardenganpola POLIGONAL. Pedoturbation (churning) is a process which homogenizes the soil profile due to the infilling of the cracks by surficial material during dry season. The process in Vertisols is also called self-mulching or self-swallowing. Diunduhdari: ………….. 25/2/2013

  12. TANAH VERTISOLS PROSES GENESIS TANAH Selamasikluspengeringanterbentuklahretakan-retakan, sedangkanpadasaatpembasahanterbentuk “tekanangeser” yang menghasilkanpembentukan “slickensides” dan/ataupenghalusanpermukaan “sphenoids”. Keduasifatinimemerlukan material yang bersifatplastis. Tekanan lateral yang berkembangdalamtanah-tanahinijauhlebihbesardibandingkan dg tekananvertikalakibatpembengkakan (swelling). Di dalamtanah, komponenvertikaldaritekanan “swelling” mencakup “bobot /berat” dari material disebelahatasnya. The moisture conditions above and below a point within the soil determines the net pressure and angle of shear. As such, the near surface horizon develop cracks and may have only a few slickensides since both the horizontal and vertical pressures are small (the net pressure being much lower than the sheat strength of the material). In deeper horizons, typically from 50 to about 125 cm below the surface, slickensides development is maximum. In these deeper layers, the net pressure is much greater than the shear strength of the material and soil movement occurs with swelling. Sphenoids develop as a result of the existence of much lower vertical and horizontal pressures in comparison to that needed for the development of slickensides. In the typical case, sphenoids would be found in between the surface horizon with cracks and deeper horizons with slickensides. Their development has been related to lower clay contents, as well as smaller proportions of smectitic clays in the colloidal fractions.

  13. TANAH VERTISOLS PROSES GENESIS TANAH Tranlokasiliatpadavertisolstidakfenomenal, namundmeikian, adanyaliat-liat “smectitic” mempunyaisemuakondisi yang diperlukanuntukprosesdispersi, translokasi, danakumulasiliatpadahorisonbawah-permukaan. In some Vertisols there is some evidence of illuviated clays in the lower soil profile, which is subjected to the least amount of pedoturbation. This process tends to obliterate all evidence of the illuviation process and it is unlikely that well-defined clay skins will be preserved, instead any translocated clay is probably engulfed in the matrix and/or slickensides as a result of shrink-swell processes. Diunduhdari: ………….. 25/2/2013

  14. TANAH VERTISOLS MODEL PEDOGENIK PEMBENTUKAN VERTISOLS (I). Model Pedoturbasi (Self-Swallowing Model) PersyaratanbagipembentukanVertisolsadalahadanya mineral liattipe “mengembang” (smectites). Adanya mineral liatinimenyebabkanterjadinyaprosesmengembang-mengkerutpadatanah. Selamamusimkeringtanahretak-retak. Selamaretakaninimembuka, material tanahpermukaanjatuhmasukkedalamretakanolehadanayagayaangin, aktivitasbinatangatauerosioleh air. On rewetting the clays hydrate and expand. As expansion takes place, the cracks close, but because of the 'additional' material now present in the lower parts of the profile, a greater volume is required and the expanding material presses and slides the aggregates against each other developing slickensides. Diunduhdari: ………….. 25/2/2013

  15. TANAH VERTISOLS MODEL PEDOGENIK PEMBENTUKAN VERTISOLS (II). Model Mekanistik This model is based on the failure along shear planes (slickensides) of plastic soil material when swelling pressures generated by hydration of clays exceed the shear strength of the soil material. Stress is relieved by an upward movement that is constrained by the weight of the overlying soil material, resulting in a failure shear plane that is usually inclined at 10 - 60° above the horizontal. This model does not require that surface material falls into cracks. Instead, surface material is transported upward along the slickensides to produce the microknolls of the gilgai-relief. Once microrelief is established, soil processes are driven largely by small-scale variations in hydrology and microclimate, and less so by pedoturbation. Diunduhdari: ………….. 25/2/2013

  16. TANAH VERTISOLS SIFAT DAN CIRI VERTISOLS Lima zone atau horizons denganpenciristrukturalnyadapatditemukanpadaVertisols, meskipuntidakselalusemuanyaditemukanbersamadalamsatuprofiltanah, danurutannyamungkinjugaberagam. Zone 1: Zone inidaripermukaanhinggakedalamansekitar 25 cm ataulapisanolahbajakkalauada. Zone inidicirikanolehadanyaagregatprismatik yang berukuranbesar, hingga30 cm lebarnya, yang dihasilkandariprosesretakan-retakan. Materialnyakerasatausangatkeraskalaukeringdanagregatprismatikdapatmemisahkandirimanjadigumpalbersudut yang kasarukurannya. Zone 2: This zone is typically 10 to 30 cm thick and characterized by coarse angular blocky elements that may occur aggregated into discernable prisms. If overlain by a plow zone, it may represent a root restricting layer for agricultural crops. Zone 3: This zone may vary in thickness from 10 to over 100cm. Soil Taxonomy refers to the structural elements in this zone as 'wedge-shaped natural structural aggregates that have their long axis tilted 10 to 60 degrees from the horizontal'. These structural aggregates have an orthorhombic form, are generally 5 to 10 cm long along their long axis; and smooth or striated ped faces. Their mode of formation is related to the slickensides, which are characteristic of zone 4. Diunduhdari: ………….. 25/2/2013

  17. TANAH VERTISOLS SIFAT DAN CIRI VERTISOLS Zone 4: Zone inimenjaditempatpembentukanbidang-geserdantebalnyaberkisar from 25 - 100 cm. Istilah “bidanggeser” menunjukkan “permukaan” halusdanmengkilap yang jugadapat “be grooved or striated”. Dalam zone ini, bidanggesermenempatiluasansekitar600 - 2000 cm2. Their surface topography is not flat, but curved or slightly undulating. The net result of the inclined arrangement is to produce a set of intersecting slickensides arranged in a synclinal form. The deepest part of the syncline is between 50 and 125 cm below the surface, while the shallower arms may reach within 25 cm of the surface. The amplitude of the two arms represents the amplitude of the gilgai and may vary from about 3 m to more than 25 m. The thickness and expression of zones 2 &3 are a function of the depth at which the arms of the slickensides approach the surface. Diunduhdari: ………….. 25/2/2013

  18. TANAH VERTISOLS SIFAT DAN CIRI VERTISOLS Zone 5: Zone iniberadadibawah zone 4 ataulangsungdibawah zone 3. Zone inimengalamivariasikelengasansedikitsaja, bersifatmasif, danmenunjukkanakumulasigipsum, carbonates dangaram-garamlarutlainnya.. Variations from the model profile is the rule rather than the exception. One or more of zones 2, 3 or 4 may be absent, but 'conceptually zone 3, 4 or both must be present for recognition as a Vertisol. The expression of zones 2, 3 and 4 will show considerable variation as a function of soil moisture content and variation in intrinsic soil attributes (variation in clay type and content), however their relative positions are usually sequential. Generally, the clay content is very high in Vertisols and the dominant clay minerals are 2:1 type minerals (smectites, montmorillonites). These clay minerals have the outstanding feature to expand (swell) when wet and shrink when dry. Therefore, pronounced changes in volumes with changes in soil moisture result in deep cracks in the dry season and very plastic and sticky soil consistency when wet. Due to the high clay content of expanding character the cation exchange capacity of the whole soil is high. A high clay content is also associated with slow permeability but the water adsorption is high. Diunduhdari: ………….. 25/2/2013

  19. TANAH VERTISOLS SIFAT DAN CIRI VERTISOLS Bidanggeser “Slickensides”menjadicirikhasdariVertisols. They are defined as polished and grooved surfaces produced by one soil mass sliding past another. The formation of slickenside features is related to swelling pressures which exceed the shear strength of the soil under overburden-pressure confinement. The shear strength of a soil is a function of cohesion plus the angle of internal friction, which is low in clay soils. The cohesion is a function of bulk density, clay content, clay mineralogy, and is inversely related to moisture content. Generally, lateral swelling pressures in soils are much larger than vertical swelling pressures, as the latter is substantially reduced by the overburden pressure. Maximum slickensides are between 50 and 125 cm depth, however, fewer slickensides are found at depths between 25 and 50 cm. At such depths both vertical and horizontal pressures are small. As the moisture changes become limited at 125 cm depth, slickensides become scarce below this depth. Shearing occurs at an angle of 30 to 50 degrees from the horizontal and it is dependent on moisture and the swelling pressures, which vary vertically, horizontally, and temporally. Diunduhdari: ………….. 25/2/2013

  20. TANAH VERTISOLS SIFAT DAN CIRI VERTISOLS Slickensideshanyadapatterbentukkalaumaterialnyaplastis. Bidanggeser (slickensides , stress cutans) sangatberbedadenganselimut-liat (argillans) yang ditemukanpadapermukaanagregatdandihasilkandariprosestranslokasiliat. The latter have sharp outer and inner boundaries with distinct extinction patterns and are often finely layered (laminar fabric). The relatively small slickensides developed by pedogenesis must not be confuse with large slickensides of the substratum which in alluvial and lacustrine sediments is a feature of the parent material. Diunduhdari: ………….. 25/2/2013

  21. TANAH VERTISOLS SIFAT DAN CIRI VERTISOLS The organic matter content is generally low (0.5 - 3 %) in spite of the usual dark soil color. Complexation or chelation of organic colloids to clay minerals of the smectite group probably darkens the mineral. Some of the dark color may also be related to presence of manganese oxides. The dark black color may be also due to the parent material (e.g. Vertisols derived from basalt). The Chrom great groups of Vertisols are brownish in color and typically have small amounts of montmorillonites. These great groups typically have large amounts of iron oxyhydroxides and are well-drained. Kankars (carbonate glaebules or nodules) are basically lime concretions that are found in Vertisols. Many Vertisols are formed in calcareous parent material and have kankars throughout the profile. In deeper horizons, it is also common to find calcic horizons. Drying, in the presence of Fe and Mn, results in the formation of hard concretions. Diunduhdari: ………….. 25/2/2013

  22. TANAH VERTISOLS SIFAT DAN CIRI VERTISOLS StrukturtanahVertisolsbersifattemporer. Ukuranstruktur , bentuk, grade dankonsistensisemuanyaberhubungandnegankondisilengastanah. The depth at which the different structural elements are expressed may also be a function of moisture conditions in different parts of the profile. Ideally, structural assessments should be made under different moisture conditions. SeringkaliVertisolsmenunjukkanstrukturgumpalbersudut (agregat yang berbentukbaji “wedge”). Diunduhdari: ………….. 25/2/2013

  23. TANAH VERTISOLS SIFAT DAN CIRI VERTISOLS Cirimikro-relief yang khasadalah knolls (gundukan) dan basins (cekungan) padalanskapVertisol. Cekunganlebihbasahdaripadagundukan, karenaadanyapelepasan air melaluiretakan-retakandangenangan air selamaperiodebasah. They exhibit higher organic matter contents and are often more saline than the microknolls. The knolls are drier, have a higher calcium carbonate content and are in the erosional positions. Minibasins and microknolls show a repetitive but irregular pattern within a Vertisol landscape with distances of about 3 to 10 m between the knolls. The topography related to Vertisols is called 'Gilgai micro-topography'. Various forms of gilgai have been reported: round, mushroom, tank, wavy, lattice, stony, and depressional. The form is related to landscape shape, clay content and type, and soil moisture regime. A fine, angular blocky structure, described by some as 'nutty' may develop in surfaces that have a very high montmorillonitic clay content. In the dry season they show a very hard consistence and appear as loose gravel strewn on the surface. In previous classification systems these soils were called Grumosols. KebanyakanVertisolsmempunyaiepipedonmollicdanhorisonpenciricambic, tetapibeberapalainnyamempunyaihorisonpenciribawahpermukaan , termauskargillicataunatrik.  Diunduhdari: ………….. 25/2/2013

  24. TANAH VERTISOLS KLASIFIKASI VERTISOLS PersyaratanuntukmemenuhikualifikasiVertisoladalah: Clay content of at least 30 % to a depth of at least 50 cm, or a lithic or paralithic contact, duripan, or a petrocalcic horizon if shallower Cracks that open and close periodically Evidence of soil movement (e.g. slickensides, wedge-shaped aggregates) Any soil temperature regime, except pergelic (i.e., Gelisols) Soil moisture regime must be erratic to allow for cracking in dry season and swelling in wet season Gilgai surface topography is not considered as a requirement to meet a Vertisol. Cultivation practice may erase gilgaimicrotopography. AdaenamsubordodidalamordoVertisol. They are differentiated by aquic conditions, soil moisture regime, and on the cracking characteristics of the soil. Note that although the formative elements for soil moisture regimes are used in naming Xererts, Torrerts, Usterts, and Uderts, the names do not necessarily mean that the soils have those soil moisture regimes. Diunduhdari: ………….. 25/2/2013

  25. TANAH VERTISOLS KLASIFIKASI VERTISOLS Aquerts: Vertisols which are subdued aquic conditions for some time in most years and show redoximorphic features are grouped as Aquerts. Because of the high clay content the permeability is slowed down and aquic conditions are likely to occur. In general, when precipitation exceeds evapotranspirationponding may occur. Under wet soil moisture conditions iron and manganese is mobilized and reduced. The manganese may be partly responsible for the dark color of the soil profile. Cryerts: They have a cryic soil temperature regime. Cryerts are most extensive in the grassland and forest-grassland transitions zones. Xererts: They have a thermic, mesic, or frigid soil temperature regime. They show cracks that are open at least 60 consecutive days during the summer, but are closed at least 60 consecutive days during winter. Diunduhdari: ………….. 25/2/2013

  26. TANAH VERTISOLS KLASIFIKASI VERTISOLS Torrerts: Tanah-tanahinimempunyairetakan-retakan yang menutupselamakurangdari 60 hariberturutanpadasaatsuhulapisantanahpermukaan 50 cm lebihdari 8°C. Usterts: Tanah-tanahinimempunyairetakan-retakan yang membukaselama minimal 90 harikumulatifsetiaptahun. Secara global, ordotanahini paling luassebarannya, meliputitanah-tanahVertisolsdidaerahtropisdaniklim monsoon. Diunduhdari: ………….. 25/2/2013

  27. TANAH VERTISOLS KLASIFIKASI VERTISOLS Uderts: Tanah-tanahinimempunyairetakan yang membukaselamakurangdari 90 harikumulatif per tahun, dankurangdari 60 hariberturutanselama summer. Great groups are differentiated by subsurface diagnostic horizons (e.g. salic, calcic, natric, gypsic horizons), the presence of a duripan (e.g. Duraquerts, Durixererts), organic carbon content (e.g. Humicryerts), or reaction (electrical conductivity is less than 4 dS/m and pH in 1:1 water of 5 or less in 25 cm or more within top 50 cm - e.g. Dystrusters, Dystraquerts). Beberaparezimlengastanahpadatingkatsugroupberagammulaidarikondisikeringhinggabasah: Xeric (e.g. Xeric Epiaquerts), Aridic (e.g. AridicEpiaquerts), Udic (e.gUdicHaplusterts), Ustic (e.g. UsticDystraquerts), and Aquic (e.g. AquicDystrusterts, AquicSalitorrerts). Diunduhdari: ………….. 25/2/2013

  28. TANAH VERTISOLS KLASIFIKASI VERTISOLS Warnatanahdigunakanuntukmembedakan subgroup 'aeric' dariVertisols. Soils that have in one or more horizons between either an Ap horizon or a depth of 25 cm from the mineral soil surface, whichever is deeper, 50 percent or more colors as follows: Nilai HUE 2.5R ataulebihmerah, dan/atau Nilai VALUE, lembab, 6 ataulebihdan KHROMA 3 ataulebih; atau Nilai VALUE, lembab, 5 ataukurangdan KHROMA 2 ataulebih; atau Nilai HUE 5Y dan KHROMA 3 ataulebih; atau KHROMA 2 ataulebih, dantidakadakonsnetrasiredoks (mis. AericEndoaquerts). Soil color is used also to differentiate the 'chromic' subgroup of Vertisols. The chromic characteristic encompass soils that have, in one or more horizons within 30 cm of the mineral soil surface, 50 percent or more colors as follows: VALUE, lembab, 4 ataulebih; atau VALUE, kering, 6 ataulebih; atau KHROMA 3 ataulebih (mis. Chromic Epiaquerts). Diunduhdari: ………….. 25/2/2013

  29. TANAH VERTISOLS KLASIFIKASI VERTISOLS Vertisols yang tipis (dangkal) diklasifikasikandengansebutan 'leptic' (tanh yang mempunyaikontakdensik, lithic, atauparalithic , didalam 100 cm tanah mineral permukaan) atau 'lithic' (mis. LepticSalaquertsatauLithicHaploxererts).   Vertisols which are low in clay content are differentiated as 'entic'. To meet the 'entic' designation the Vertisol must have a layer 25 cm or more thick that contains less than 27 percent clay in its fine-earth fraction and has its upper boundary within 100 cm of the mineral soil surface (e.g. EnticSalaquerts, EnticHaplotorrerts). Tanah-tanahdisebut 'halic' kalaukandungangaramnyatinggi. Tanah-tanahinimemenuhikriteria : seluruhlapisan 15 cm ataulebihtebalmempunyaikonduktivitaselektrik minimal 15 dS/m ataulebih (tanah: air 1:1) selama 6 bulanataulebih per tahun , dalam 6 tahunataulebihselamaperiode 10 tahun (mis. HalicDurixererts). Vertisols with a high sodium content are classified as 'sodic' (e.g. SodicDurixererts). They must have an exchangeable sodium percentage of 15 or more (or a sodium adsorption ratio of 13 or more) for 6 or more months per year in 6 or more out of 10 years. Diunduhdari: ………….. 25/2/2013

  30. TANAH VERTISOLS Coefficient of linear extensibility (COLE) and bulk densities of selected Vertisols. Diunduhdari: http://www.fao.org/wairdocs/ILRI/x5493E/x5493e05.htm………….. 1/3/2013

  31. TANAH VERTISOLS KARAKTERISTIK PENCIRI Soils at higher elevations and on steeper slopes formed in the same parent material as Vertisols are classified as Inceptisols and Alfisols and they may have vertic properties. In a catenary association Alfisols may occur on the top of the slopes - Entisols, Inceptisols, and Alfisols with vertic properties on the erosionalhillslope positions - and Vertisols on the lower slopes and in the depressions. The main associated soils formed in calcareous parent material are Ustolls, Aqualfs in the less calcareous clays, and soils in vertic subgroups of Ustolls and Aquolls on nearly level slopes. With advancement of leaching and the formation of an argillic horizon, the soil would evolve into Alfisols (e.g. VerticHapludalfs). Leaching also promotes the destruction of smectites, i.e., the vertic properties of the soils are destroyed and Alfisols are formed. A number of Inceptisols, Entisols, Alfisols, Mollisols, Ultisols, and Aridisolsintergrade to Vertisols at the subgroup level. These soils have vertic characteristics such as cracking, slickensides or wedge-shaped aggregates, but not enough to be Vertisols. Diunduhdari: ………….. 25/2/2013

  32. TANAH VERTISOLS PembentukanHorison VERTIK Pembentukanagregatstruktural yang khas (`vertic structure') merupakanprosesgenetikutamadalamVertisols. Strukturtipikalinidapatditemukandalamsolum, tetapiekspresi yang paling kuatadapada`vertic horizon'; derajatperkembangandanukuranagregatberubahsecarabertahapdnegankedalamantanah. When the saturated surface soil starts to dry out, shrinkage of the clayey topsoil is initially one-dimensional and the soil surface subsides without cracking. Upon further drying, the soil loses its plasticity and tension builds up until the tensile strength of the soil material is locally exceeded and the soil cracks. Cracks are formed in a pattern that becomes finer as desiccation proceeds. In most Vertisols, the surface soil turns into a `surface mulch' with a granular or crumb structure. Vertisols, which develop surface mulch, are called `self-mulching‘. Granules or crumbs of the mulch fall into cracks. Upon re-wetting, part of the space that the soil requires for its increased volume is occupied by mulch material. Continued water uptake generates pressures that result in shearing: the sliding of soil masses against each other. Shearing occurs as soon as the `shear stress' that acts upon a given volume of soil exceeds its `shear strength'. The swelling pressure acts in all directions. Mass movement along oblique planes at an angle of 20 to 30 degrees with the horizontal plane resolves this pressure Diunduhdari: http://www.fao.org/docrep/003/Y1899E/y1899e06.htm………….. 1/3/2013

  33. TANAH VERTISOLS Vertisolsmempunyaikandungan mineral liattipemengembang yang sangattinggi. Merekamengalamiperubahan volume yang sangatnyatadneganadanyaperubahanlengastanah. Merekamempunyairetakan-retakandipermukaan yang membukadanmenutupsecaraperiodik, danmenunjukkanbukti-buktipergerakantanahdalamprofilnya. Karenamerekamengembangketikabasah , vertisolsmerembeskan air sangatlambatdanhanyasedikitmengalamipencucian. Kesuburanalamiahnyacenderungtinggi. Vertisolsmeliputisekitar 2% daripermukaanlahanduniaygbebases Diunduhdari: ………….. 25/2/2013

  34. TANAH VERTISOLS KonsepsentraldariVertisolsadalahtanah-tanah yang mempunyai (kaya) kandungan mineral liattipemengembangdanmempunyainretakan-retakanpermukaan yang lebardandalam. Tanah-tanahinimengkerutbilakeringdanmengembangbilamenjadilebihbasah. Diunduhdari: http://urbanext.illinois.edu/soil/orders/soiord.htm ………….. 28/2/2013

  35. TANAH VERTISOLS Tanah-tanahvertisolsberkembangpadabahanindukberteksturhalusdengan > 60% liat, minimal separuhnyaberupamontmorillonit. Proses genesis tanah yang dominan : retakan, argilli-pedoturbation (pencampuranliatdalampedon) danpergerakan material karenamengembang-mengkerutnyaliatselamasikluspembasahan/pengeringan. Tanah-tanahinimempunyaiduahorison yang khas (B atau C): slickensides (ss = horisonbawah-permukaanberliatygmempunyai “polished and grooved ped surfaces -'slickensides', atauagregat yang berbentuk wedge ) danvertik (v = horizon denganretakan yang lebar & dalamketikakering, sehinggamemungkinkan material permukaanturunkebawahsepanjangretakandanmenyebabkantanahmenjadi “heave”). Sikluspembasahandanpengeringanmenyebabkanliatmengembangdanmengkerut. Diunduhdari: http://soilweb.landfood.ubc.ca/processes/vertisols.htm ………….. 28/2/2013

  36. TANAH VERTISOLS Retakan-retakandipermukaantanahVertisoldariUtah TingginyakapasitasVertisolsuntukmengembangdanmengkerutmenciptakanretakan-retakandipermukaantanah. Retakan-retakaninicukuplebaruntukmembuat “the terrain treacherous” bagibinatang. Material permukaanmengakumulasidalamretakaniniselamamusimkeringdan "swallowed" olehtanahpadamusimbasah, sehinggamenghasilkanaksimencampur-sendiripadatanahVertisols. Diunduhdari: http://www.cals.uidaho.edu/soilorders/i/Vert_06b.jpg ………….. 28/2/2013

  37. TANAH VERTISOLS SUB-ORDO Aquerts - Vertisols with a water table at or near the surface for much of the year Cryerts - Vertisolsdidaerahiklimdingin Xererts - temperate Vertisols with very dry summers and moist winters Torrerts - Vertisolsdidaerahiklimkering Usterts - Vertisolsdidaerahiklim semiarid dansubhumid Uderts - Vertisolsdidaerahiklimbasah Diunduhdari: http://www.cals.uidaho.edu/soilorders/vertisols%20suborders.htm ………….. 28/2/2013

  38. TANAH VERTISOLS HorisonpadaVertisols The A horizon, called topsoil by most growers, is the surface mineral layer where organic matter accumulates.  Over time, this layer loses clay, iron, and other materials to leaching.  This loss is called eluviation. Materials resistant to weathering, such as sand, tend to remain in the A horizon as other materials leach out.  The A horizon provides the best environment for the growth of plant roots, microorganisms, and other life. The C horizon lacks the properties of the A and B horizons.  It is the soil layer less touched by soil-forming processes and is usually the parent material of the soil. Diunduhdari: http://www2.vcdh.virginia.edu/madison/webship/rotorua/orders.html ………….. 28/2/2013

  39. TANAH VERTISOLS a vertic h. starting within 100 cm of the soil surface; dan after the upper 20 cm have been mixed, 30 percent or more clay between the soil surface and the vertic h. throughout; dan Retakan-retakan yang membukadanmenutupsecaraperiodik. Diunduhdari: http://wwwuser.gwdg.de/~kuzyakov/soils/WRB-2006_Keys.htm ………….. 28/2/2013

  40. TANAH VERTISOLS Vertisols are dark clays and difficult to work. Good management can bring them to medium or high potential. Diunduhdari: http://www.fao.org/docrep/u8480e/U8480E0b.htm ………….. 28/2/2013

  41. TANAH VERTISOLS RETAKAN DI PERMUKAAN Cracks, surface mulch and soil structure in a Vertisol during the dry season Cracks are formed in a pattern that becomes finer as desiccation proceeds. In most Vertisols, the surface soil turns into a ' surface mulch ' with a granular or crumb structure. Vertisols, which develop surface mulch, are called ‘ self-mulching'. Cracks, surface mulch and soil structure in a Vertisol during the dry season Diunduhdari: http://www.fao.org/docrep/003/Y1899E/y1899e06.htm ………….. 1/3/2013 Diunduhdari: http://www.isric.org/isric/webdocs/docs//major_soils_of_the_world/set3/vr/vertisol.pdf? ………….. 28/2/2013

  42. PENGELOLAAN VERTISOLS Large areas of Vertisols in the semi-arid tropics are still unused or are used only for extensive grazing, wood chopping, charcoal burning and the like. These soils form a considerable agricultural potential but adapted management is a precondition for sustained production. The comparatively good chemical fertility and their occurrence in extensive level plains where reclamation and mechanical cultivation can be envisaged are assets of Vertisols. Kendalaserius yang dihadapiadalahkarakteristikfisikatanahdansulitnyapengelolaan air.. SISTEM PERTANIAN PADA Vertisols The agricultural use of Vertisols ranges from very extensive (grazing, collection of fire wood, charcoal burning) through smallholder post-rainy season crop production (millet, sorghum, cotton, chick peas) to small-scale (rice) and large-scale irrigated agriculture (cotton, wheat, barley, sorghum, chickpeas, flax, noug (GuzotiaAbessynica) and sugar cane). Cotton is known to perform well on Vertisols allegedly because cotton has a vertical root system that is not severely damaged by cracking of the soil. Tree crops are generally less successful because tree roots find it difficult to establish themselves in the sub- soil and are damaged as the soil shrinks and swells. Praktekpengelolaanuntukproduksitanamanharusdiarahkanpadapengelolaan air yang dikombinasikandengankonservasiatauperbaikankesuburantanah. Diunduhdari: http://www.isric.org/isric/webdocs/docs//major_soils_of_the_world/set3/vr/vertisol.pdf? ………….. 28/2/2013

  43. PENGELOLAAN VERTISOLS ManajemenlahansecarafisikpadaVertisols Sifat-sifatfisikadanrezimlengas-tanahpadaVertisolsmenjadikendalaseriusbagipengelolaannya. The heavy soil texture and domination of expanding clay minerals result in a narrow soil moisture range between moisture stress and water excess. Tillage is hindered by stickiness when the soil is wet and hardness when it is dry. The susceptibility of Vertisols to waterlogging is the single most important factor that reduces the actual growing period (below estimates based on climatic data). Kelebihan air selamamusimhujanharusdapatdisimpanuntukdigunakanpascamusimhujan (‘panen air hujan') padaVertisols yang mempunyaisifatlajuinfiltrasisangatlambat. Diunduhdari: http://www.isric.org/isric/webdocs/docs//major_soils_of_the_world/set3/vr/vertisol.pdf? ………….. 28/2/2013

  44. PengelolaanVertisolsuntukmemperbaikirezimlengastanah: Evacuation of excess surface water – SISTEM SURJAN Drainage permukaandnegansistemsurjan (bedenganlebardenganparitdalam), dapatmelindungitanamandariefekburukakibatjenuhnya zone perakaran. Air drainage dapatdisimpandalamkolam-kolamkecildandigunakanuntukkeperluanternakdantanamansayuran yang dibudidayakan. This practice proved very successful in the Ethiopian Highlands where the yields of local wheat varieties increased by 150 % and horse bean yields went up by 300 %. The only disadvantage of broad bed and furrow systems recognised so far is that they promote soil erosion by concentrating water flow in the furrows. The broad bed and furrow technology solves problems on individual farmers’ fields but solutions have still to be found to bring the runoff water safely down to the lowest part of the landscape (e.g. along grassed waterways) without enhancing erosion of neighbouring farmland. A participatory approach involving all stakeholders is needed to solve this problem at watershed scale. Diunduhdari: http://www.isric.org/isric/webdocs/docs//major_soils_of_the_world/set3/vr/vertisol.pdf? ………….. 28/2/2013

  45. PengelolaanVertisolsuntukmemperbaikirezimlengastanah: Storage of excess water within the watershed – EMBUNG Kalaukelebihan air hujandapatdipanendandisimpandalamembung (micro-dams), air inidapatdigunakanuntukirigasiVertisolsdidaerahbawahannya.. Seepage losses from the dams benefit the ecosystem as a whole, since the water will surface as recharge in lower landscape positions. Livestock benefit from these micro-dams in many ways, e.g. by increased fodder availability from crop residues, presence of drinking water and increased fodder production in recharge zones. Even though micro-dam projects are generally appreciated as successful, salinisation and sodification of the irrigation perimeters and high percolation losses are serious hazards. At some of the dam sites, up to 50 % of the harvested water is lost each year. This is a direct consequence of the swell-shrink behaviour of smectite clay. The use of a membrane or of other construction materials, e.g. more weathered clay which may occur in the same landscape, has been suggested as a remedy. Akumulasisalinitastanahmenjadimasalahserius. Dalamwaktusatudekadesaja, salinitastanahdapatmenjadisangattinggidanseluruhembungharus “to be demolished “ danlahandisekitarnyaharusdibiarkanmemulihkandirinyaselamabeberapatahun, sebelumdibudidayakankembali. Diunduhdari: http://www.isric.org/isric/webdocs/docs//major_soils_of_the_world/set3/vr/vertisol.pdf? ………….. 28/2/2013

  46. PengelolaanVertisolsuntukmemperbaikirezimlengastanah: Water harvesting in areas with Vertisols – PANEN AIR HUJAN The deep and wide cracking of Vertisols retards wetting of the surface soil after a dry spell. Management should therefore be directed at storing water in the subsurface soil; the greater soil moisture reserves extend the possible length of a crop’s growing period. Beberapateknikpanen air hujanpadavertisolsadalah: Construction of small ponds for harvesting (drainage) water and keeping it in the higher parts of a watershed. This water can be used later, e.g. for strategic irrigation of vegetable gardens and/or for watering livestock. Contour ploughing and bunding to enhance infiltration of water in the soil. A beneficial side effect of contour bunding is that it diminishes soil erosion, which is a severe problem of many Vertisols on slopes. In the highlands of Northern Ethiopia, continued contour ploughing resulted in stepped landscapes (‘dagets’) with step heights from 0.3 m to 3 metres. Grasses are planted on the riser and a more or less large strip of grass is maintained on the shoulder. Mulsavertikaluntukmemperbaikiinfiltrasi air kedalam subsoil. Resitutanamanditempatkansecaravertikaldalamparit-paritkonturdenganbagian yang munculdipermukaantanahsekitar 10 cm. Parit-paritdenganbarisanmulsavertikaliniberjarakpisak 4 - 5 m. Diunduhdari: http://www.isric.org/isric/webdocs/docs//major_soils_of_the_world/set3/vr/vertisol.pdf? ………….. 28/2/2013

  47. PengelolaanVertisolsuntukmemperbaikirezimlengastanah: PerbaikanKondisiPerakartan Beberapateknikuntukmemulihkankembalistrukturtanah : Soil heating/burning is practised in the Ethiopian highlands (the technique is locally known as ‘guie’). Burning causes the clay fraction to fuse to sand-sized particles. Flood fallowing’ (flooding the land for 6 to 9 months) has been tried on low-lying Vertisols. Gases produced by fermentation and redistribution of oxides improve rooting conditions in heavy clay surface soils. Pengolahan-datamtanah-tanahVertisols yang mempunyaihorison “indurated “ (mis. BeberapaVerisolsCalcicdanGypsicVertisolsdanDuricVertisols) untukmenghancurkan subsoil yang kerasdankompak. Diunduhdari: http://www.isric.org/isric/webdocs/docs//major_soils_of_the_world/set3/vr/vertisol.pdf? ………….. 28/2/2013

  48. Pengelolaan Status Hara padaVertisols Vertisolsmerupakantanah-tanah yang suburdidaerahtropikabermusimkering. Tanah-tanahinikayakationbasa, kalsiumdan magnesium mendominasikomplekspertukaran. Banyaksistempertaniantradisionalmelibatkanperiodebera (kosong) 1 – 4 tahun , dimanaVertisolsdapatmemulihkankembali BOT nyapadatanahlapisanatas. Increased population pressure has now reduced the proportion of fallow land (read: the fallow period) and many areas are left in fallow only when completely degraded. Trials have shown that continuous cropping can be sustainable provided that soil and water conservation and fertiliser management are adequate. Diunduhdari: http://www.isric.org/isric/webdocs/docs//major_soils_of_the_world/set3/vr/vertisol.pdf? ………….. 28/2/2013

  49. Pengelolaan Status Hara padaVertisols BanyakVertisolsdefisien nitrogen, sesuaidneganrendahnyakandungan BOT. Pupuk Nitrogen harusdiaplikasikansedemikianrupasehinggadapatdihindarkanpenguapanamoniak yang berlebihandanpencuciannitrat yang intensif. Placement of nitrate fertiliser in the root zone is best in dry regions whereas split banded application is preferred in wet conditions (Van Wambeke, 1991). If nitrogen is supplied in the ammonium form, is may be retained by the exchange complex of Vertisols, which curbs (leaching) losses. Diunduhdari: http://www.isric.org/isric/webdocs/docs//major_soils_of_the_world/set3/vr/vertisol.pdf? ………….. 28/2/2013

  50. Pengelolaan Status Hara padaVertisols Many Vertisols have a low content of available phosphorus. In the East-African highlands, Vertisols on weathered basalt showed little response to application of phosphate under low-intensity farming but phosphorus became strongly limiting if farming was intensified (and yields went up). Aridic , Alic and Chromic Vertisols contain much exchangeable aluminium and are notorious for inactivating fertiliser phosphate. In places Vertisols are low on sulphur and/or zinc. It is generally believed that application of animal manure would improve soil organic matter and soil physical properties, but trials remained largely inconclusive. Crop residues should be returned to the land but are rather used as animal feed, fuel and building materials. Penelitiandneganpupukhijau (legumes) menunjukkanpeningkatganhasil yang signifikantanamanserealiadanpeningkatanefisiensiserapanpupuk. Kombinasibedenganlebardanparit-dalamdenganaplikasipupukfosfatdantumpangsarisereal-legume dapatmemanfaatkanmanfaatintekasitanaman-ternak. The legumes overgrow the cereal stover after harvest (Jutziet al., 1987; Gryseels, 1988). Diunduhdari: http://www.isric.org/isric/webdocs/docs//major_soils_of_the_world/set3/vr/vertisol.pdf? ………….. 28/2/2013

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