DASAR ILMU TANAH
Tanah bermacam-macam
Klasifikasi Tanah Usaha membeda-bedakan mengelompokkan
tanah berdasarkan sifat-sifatnya
Tujuan 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)
Klasifikasi Teknikal: berdasarkan tujuan khusus dgn memilih ciri2 ttt yg pgrhi kemampuan dan penggunaannya -
-
Klasifikasi Kemampuan Lahan USDA - Klasifikasi Kesesuaian Lahan FAO -
Mengapa tanah diklasifikasikan? • Menata atau mengorganisasi pengetahuan tentang tanah • Mengetahui hubungan antara individu tanah (ilmiah) • Mengelompokkan tanah untuk tujuan lebih praktis – Penggunaan optimal – Hazard/Pembatasan/Penilaian remidiasi – Produktivitas potensial – Penyampaian informasi yang efisien di dalam komunikasi ilmiah
Sejak th 1988 hanya gunakan sistem Taksonomi Tanah. Sebelum 1988 ada 3 :
Pusat Penelitian Tanah (PPT) - FAO/UNESCO - Taksonomi Tanah (USDA). -
dikembangkan oleh Soil Survey Staff (USDA), tahun 1975 Terus direvisi 2ed, 1999
ada 6 kategori yaitu Order, Suborder, Great group, Subgroup, Family dan Series.
Categories in ST:
Order – key soil properties resulting from major soilforming 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, extragrades Family – properties important to plant growth (texture, mineralogy, soil temperature regime, etc.) Series – soil morphology
1. 2.
Orders (12) (surface and subsurface diagnostic horizons) Suborders (55) (Soil temperature. and moisture regimes)
3. 4.
Great group (238) (subsurface diagnostic horizon) Subgroup (1243) (drainage, lithic contact, PM, clay type)
5. 6.
Family (7504) (Texture of diagnostic surface horizon) Series (about 19,000) in U.S.
TAKSONOMI TUMBUHAN vs TAKSONOMI TANAH Kategori
Nama
Kategori
Nama
Phylum
Pteridophyta
Order
Alfisol
Kelas
Angiospermae
Sub-order
Udalf
Sub-kelas Dicotyledoneae
Greatgroup
Hapludalf
Order
Rosales
Sub-group
Aquic Hapludalf
Family
Leguminoseae
Family
Aquic Hapludalf, berlempung halus, Campuran, Aktif, Isohipertermik
Genus
Trifolium
Seri
Lape
Species
T. repens
(Phase)
Berbatu
Differentiating Characteristics in ST: Diagnostic
epipedons Diagnostic subsurface horizons Other diagnostic soil characteristics Soil moisture and temperature regimes
horison penciri yg terbentuk di
permukaan tanah. tidak sinonim dg horizon A dapat mencakup sebagian horizon B.
Surface horizons Influenced strongly by biochemical and geochemical processes Correspond with A, E, and sometimes upper B horizons Important in classifying soils
Histik: Mollik:
Umbrik: Anthropik:
Ochrik:
Plaggen:
Folistik:
Bahan organik (BO) tinggi (>75%), tebal 20-40cm. BO >1%, warna gelap dg value dan kroma <3 (lembab) dan value < 5 (kering), tebal >18cm, KB >50%. seperti molik tetapi KB <50%. seperti molik, tetapi mengandung >1500 ppm P2O5 larut dalam 1% as sitrat. warna terang (value dan kroma lembab >3), BO <1% atau keras-sangat keras dan masif. horizon buatan, akibat penggunaan pupuk kandang yg terus menerus, tebal >50cm, berwarna hitam. tanah atas BO, jenuh < 30 hari
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.
Agrik:
Gipsik : Petrogipsik: Natrik : Oksik :
Salik:
Sombrik :
Spodik : Sulfurik :
Plasik:
banyak mengandung gipsum (CaSO4) sekunder. horizon gipsik yg mengeras. horizon argillik yg banyak mengandung Na horizon bertekstur agak kasar, KTK <16 me/100g liat, tebal >30cm. banyak mengandung garam sekunder mudah larut, tebal >15cm. seperti umbrik, gelap, terjadi iluviasi humus tanpa Al, tidak terletak di bawah horizon albik. horizon iluviasi seskuioksida bebas dan BO. horizon yg mengandung sulfat, pH ,3.5, tdpt karatan jarosit. padas tipis tersementasi senyawa. Fe, Mn dan BO
“Soil Taxonomy" Degree of Weathering and B Horizon Development Little Entisols
Slight Aridisols Inceptisols
Moderate
Large
Extreme
Alfisols
Spodosols Ultisols Mollisols Oxisols Soils Defined by Special Constituent Materials
Andisols Histosols Vertisols Gelisols
Volcanic Ash Peat, Organic Matter “Self-Mixing” Clay Soils Soils on Permafrost
The central concept of Alfisols is that of soils that have an argillic, a kandic, or a natric horizon and a base saturation of 35% (180 cm) 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.
The 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 Soil have size horizon < 36 cm with characteristic andic >60 cm
ARIDISOL regim kelembaban tanah aridik (sangat kering) Epipedon orchic Kadang-kandang memeiliki horizon penciri lainnya
Dulu dikenal Desert soils
Tanah yang masih sangat muda (Tingkat permulaan) Tidak ada horison penciri lain kecuali epipedon ochrik atau histik (tanah sangat lembek) Aluvial/ Regosol
The 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.
The central concept of Histosols is that of soils that are dominantly organic (BO> 20%, C-organic >12% (sand), BO>30%, C-organic >18% (clay)) . 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.
Tanah muda, tetapi lebih berkembang daripada Entisol
Horison kambik
Cukup subur
Tanah ini dulu termasuk tanah Aluvial, Regosol, Gleihumus, latosol
The 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.
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. Latosol
Horison bawah terjadi penimbunan Fe dan Al oksida dan humus (horison spodik)
Lapisan atas terdapat horison eluviasi (pucat)
Podzol
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.
Tanah dengan kandungan liat tinggi (>30%) di seluruh horison) Sifat vertik (mudah mengembang dan mengerut) Ditemukan bidang kilir (slicken side) dan struktur baji Grumusol atau Margalit
Kurus, rendah UH, dan bereaksi masam. Tanah yang belum di usahakan : tanah marginal perluasan areal pertanian (ekstensifikasi) Tanah untuk perluasan lahan dibedakan menjadi 2 golongan : 1. Tanah lahan kering (Ultisol, Oxisol) 2. Tanah-tanah daerah rawa (tanah gambut) Tanah sulfaquent.
