DASAR ILMU TANAHMateri 10: Klasifikasi Tanah

KLASIFIKASI TANAH

Klasifikasi TanahUsaha membeda-bedakan mengelompokkan tanah berdasarkan sifat-sifatnyaTujuan mengetahui sifat dan ciri tanah pada masing-masing kelompok tanah (kelas tanah) sehingga memudahkan pengguna tanah untuk mengelola tanah tersebut agar dapat berproduksi secara optimal

Alami/taksonomi:berdasarkan sifat2 alami tanah tanpa dihub. dgn pengunaannya- Taksonomi Tanah (USDA)

Teknikal: berdasarkan tujuan khusus dgn memilih ciri2 ttt yg pgrhi kemampuan dan penggunaannya- - Klasifikasi Kemampuan Lahan USDA-- Klasifikasi Kesesuaian Lahan FAO

Klasifikasi

General Principles of Natural Classification Systems:The system should express general or universal relationships that exist in nature. One should be able to understand, remember, generalize, or predict from the information obtained.The scheme should be based on characteristics or attributes of things classified as related to their genesis. It should place similar things together on the basis of their properties.It is technically impossible to use all properties of the items being classified. Existing knowledge must be used to determine which properties are most important

Why Classify Soils?Organize knowledge to enable investigation and communication (structure/organization)Provide framework for establishing relationships among soils and their environment (scientific)Establish groupings for interpretations (utilitarian)Optimal useHazard/limitation/remediation assessmentPotential productivityFramework for technology transfer/information dissemination

Tanah bermacam-macam

Klasifikasi Tanah di IndonesiaSejak th 1988 hanya gunakan sistem Taksonomi Tanah. Sebelum 1988 ada 3 : - Pusat Penelitian Tanah (PPT) FAO/UNESCOTaksonomi Tanah.

Taksonomi Tanah (USDA)dikembangkan oleh Soil Survey Staff (USDA), tahun 1975 Terus direvisi 2ed, 1999ada 6 kategori yaitu Order, Suborder, Great group, Subgroup, Family dan Series.

Categories in ST:Order key soil properties resulting from major soil-forming processes (epipedons, subsurface horizons, materials, characteristics)Suborder key soil properties that are major controls on soil-forming processes, e.g., soil climate (most orders); kinds of salts (Aridisols); kinds of soil parent materials (Entisols); degree of decomposition (Histosols); presence or absence of cryoturbation (Gelisols)Great Group key soil properties that are additional controls on soil genesis (diagnostic horizons)Subgroup central concept (Typic), intergrades, extragradesFamily properties important to plant growth (texture, mineralogy, soil temperature regime, etc.)Series soil morphology

KategoriNamaKategoriNamaPhylumPteridophytaOrderAlfisolKelasAngiospermaeSub-orderUdalfSub-kelasDicotyledoneaeGreatgroupHapludalfOrderRosalesSub-groupAquic HapludalfFamilyLeguminoseaeFamilyAquic Hapludalf, berlempung halus, Campuran, Aktif, Isohipertermik GenusTrifoliumSeriLapeSpeciesT. repens(Phase)Berbatu

Differentiating Characteristics in ST:Diagnostic epipedons Diagnostic subsurface horizons Other diagnostic soil characteristics Soil moisture and temperature regimes

1. Epipedonhorison penciri yg terbentuk di permukaan tanah. tidak sinonim dg horizon Adapat mencakup sebagian horizon B.

EPIPEDONSurface horizonsInfluenced strongly by biochemical and geochemical processesCorrespond with A, E, and sometimes upper B horizonsImportant in classifying soils

EPIPEDONHistik: Bahan organik (BO) tinggi (>75%), tebal 2040cm.Mollik: BO >1%, warna gelap dg value dan kroma 18cm, KB >50%.Melanik: mirip Mollik, tetapi miliki sifat tanah andikUmbrik: seperti molik tetapi KB 1500 ppm P2O5 larut dalam 1% as sitrat. Ochrik: warna terang (value dan kroma lembab >3), BO 50cm, berwarna hitam.Folistik: tanah atas BO, jenuh < 30 hari

Horison Penciri BawahAgrik: horizon iluviasi yg terbentuk krn pengaruh pengolahan tanah shg terjadi akumulasi sejumlah debu, liat, dan humus.Albik: horison berwarna pucat (E) dg value lembab >5.Argillik: horison penimbunan liat; minimal mengandung liat >1.2 kali lebih banyak daripada kandungan liat di atasnya.Terdapat selaput liat.Kalsik: horizon yg mengandung karbonat sekunder (CaCO3 atau MgCO3) tinggi, tebal >15cm.Petrokalsik:horizon kalsik yang mengeras.Kambik: indikasi lemah adanya argillik atau spodik, tapi tidak memenuhi syarat kedua horizon tersebut.

Horison Penciri Bawah (lanjutan)Gipsik : banyak mengandung gipsum (CaSO4) sekunder.Petrogipsik:horizon gipsik yg mengeras.Natrik : horizon argillik yg banyak mengandung NaOksik : horizon bertekstur agak kasar, KTK 30cm.Salik: banyak mengandung garam sekunder mudah larut, tebal >15cm.Sombrik : seperti umbrik, gelap, terjadi iluviasi humus tanpa Al, tidak terletak di bawah horizon albik.Spodik : horizon iluviasi seskuioksida bebas dan BO.Sulfurik : horizon yg mengandung sulfat, pH ,3.5, tdpt karatan jarosit. Plasik: padas tipis tersementasi senyawa. Fe, Mn dan BO

TAKSONOMI TUMBUHAN vs TAKSONOMI TANAH

KategoriNamaKategoriNamaPhylumPteridophytaOrderAlfisolKelasAngiospermaeSub-orderUdalfSub-kelasDicotyledoneaeGreatgroupHapludalfOrderRosalesSub-groupAquic HapludalfFamilyLeguminoseaeFamilyAquic Hapludalf, berlempung halus, Campuran, Aktif, Isohipertermik GenusTrifoliumSeriLapeSpeciesT. repens(Phase)Berbatu

Soil Taxonomy"

Degree of Weathering and B Horizon DevelopmentLittleSlightModerateLargeExtremeEntisolsAridisolsInceptisolsAlfisolsSpodosolsUltisolsMollisolsOxisolsSoils Defined by Special Constituent MaterialsAndisolsVolcanic AshHistosolsPeat, Organic MatterVertisolsSelf-Mixing Clay SoilsGelisolsSoils on Permafrost

ALFISOLThe central concept of Alfisols is that of soils that have an argillic, a kandic, or a natric horizon and a base saturation of 35% or greater. They typically have an ochric epipedon, but may have an umbric epipedon. They may also have a petrocalcic horizon, a fragipan or a duripan.

ANDISOLSThe central concept of Andisols is that of soils dominated by short-range-order minerals. They include weakly weathered soils with much volcanic glass as well as more strongly weathered soils. Hence the content of volcanic glass is one of the characteristics used in defining andic soil properties

ARIDISOLAridisols is that of soils that are too dry for mesophytic plants to grow. They have either: (1) an aridic moisture regime and an ochric or anthropic epipedon and one or more of the following with an upper boundry within 100 cm of the soil surface: a calcic, cambic, gypsic, natric, petrocalcic petrogypsic, or a salic horizon or a duripan or an argillic horizon, or (2)A salic horizon and saturation with water within 100 cm of the soil surface for one month or more in normal years.

ENTISOLSThe central concept of Entisols is that of soils that have little or no evidence of development of pedogenic horizons. Many Entisols have an ochric epipedon and a few have an anthropic epipedon. Many are sandy or very shallow.

GELISOLSThe central concept of Gelisols is that of soils that have permafrost within 100 cm of the soil surface and/or have gelic materials within 100 cm of the soil surface and have permafrost within 200 cm. Gelic materials are mineral or organic soil materials that have evidence of cryoturbation (frost churning) and/or ice segeration in the active layer (seasonal thaw layer) and/or the upper part of the permafrost.

HISTOSOLSThe central concept of Histosols is that of soils that are dominantly organic. They are mostly soils that are commonly called bogs, moors, or peats and mucks. A soil is classified as Histosols if it does not have permafrost and is dominated by organic soil materials.

INCEPTISOLS The central concept of Inceptisols is that of soils of humid and subhumid regions that have altered horizons that have lost bases or iron and aluminum but retain some weatherable minerals. They do not have an illuvial horizon enriched with either silicate clay or with an amorphous mixture of aluminum and organic carbon. The Inceptisols may have many kinds of diagnostic horizons, but argillic, natric kandic, spodic and oxic horizons are excluded.

MOLLISOLSThe central concept of Mollisols is that of soils that have a dark colored surface horizon and are base rich. Nearly all have a mollic epipedon. Many also have an argillic or natric horizon or a calcic horizon. A few have an albic horizon. Some also have a duripan or a petrocalic horizon.

OXISOLS The central concept of Oxisols is that of soils of the tropical and subtropical regions. They have gentle slopes on surfaces of great age. They are mixtures of quartz, kaolin, free oxides, and organic matter. For the most part they are nearly featureless soils without clearly marked horizons. Differences in properties with depth are so gradual that horizon boundaries are generally arbitrary.

SPODOSOLS The central concept of Spodosols is that of soils in which amorphous mixtures of organic matter and aluminum, with or without iron, have accumulated. In undisrurbed soils there is normally an overlying eluvial horizon, generally gray to light gray in color, that has the color of more or less uncoated quartz. Most Spodosols have little silicate clay. The particle-size class is mostly sandy, sandy-skeletal, coarse-loamy, loamy, loamy- skeletal, or coarse-silty.

ULTISOLS The central concept of Ultisols is that of soils that have a horizon that contains an appreciable amount of translocated silicate clay (an argillic or kandic horizon) and few bases (base saturation less than 35 percent). Base saturation in most Ultisols decreases with depth.

VERTISOLS The central concept of Vertisols is that of soils that have a high content of expending clay and that have at some time of the year deep wide cracks. They shrink when drying and swell when they become wetter.