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CIRI-CIRI FISIKA TANAH

CIRI-CIRI FISIKA TANAH. SUMBER: www.swac.umn.edu/classes/ soil 2125/.../l02b. ppt ‎ . TEKSTUR TANAH. Describes the proportion of soil particle sizes: Sand Silt Clay Soil Texture influences other traits such as: Water Holding Capacity Aeration.

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CIRI-CIRI FISIKA TANAH

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  1. CIRI-CIRI FISIKA TANAH SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  2. TEKSTUR TANAH Describes the proportion of soil particle sizes: Sand Silt Clay Soil Texture influences other traits such as: Water Holding Capacity Aeration SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  3. EFEK UKURAN PARTIKEL TANAH Smaller particles – larger internal surface area SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  4. EFEK UKURAN PARTIKEL TANAH Morepores – micropores Larger pores – macropores SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  5. SEPARAT TANAH SAND 2.00 – 0.05 mm SILT 0.05 – 0.002 mm CLAY < 0.002 mm SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  6. KLASIFIKASI TEKSTUR TANAH Twelve Textural Classes Textural Triangle SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  7. DENSITAS & PERMEABILITAS TANAH DENSITAS (KERAPATAN): MASA per VOLUME D = M V SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  8. DENSITAS & PERMEABILITAS TANAH Duamacamkerapatan (densitas) dalamtanah: Particle Density – PD : BobotJenis (BJ) Bulk Density – BD: BobotIsi (BI) SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  9. DENSITAS & PERMEABILITAS TANAH BJ rata-rata tanah~ 2.65 g/cm3 BIaverage range from 1.0 – 1.8 g/cm3 Depends on amount of pore space BI = wt. dry soil = _g_ vol. dry soil cm3 e.g. BI = 650 g = 1.3 g/cm3 500 cm3 SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  10. POROSITAS TANAH Usually expressed as a percentage; e.g. 50% Two means determining porosity: • Calculate ratio water volume to total core volume • Calculate from bulk density and particle density SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  11. POROSITAS TANAH Water Volume to Core Volume wet weight (g) – dry weight (g) Porositas = ---------------------------------------- x 100% soil volume (cu cm) SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  12. POROSITAS TANAH An oven-dry soil core, volume 500 cu cm, weighs 650g. When wet, it weighs 900g. Find it’s % porosity. Porosity = 900g – 650g x 100% = 250g x100% = 50% 500 cu cm 500 cu cm Note: the unit cancellation is made possible by the metric system which defines 1 cu cm of water as weighing 1g. SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  13. POROSITAS TANAH BobotIsi (BI) vs. BobotJenis (BJ Defines the percentage of the soil that is solid matter The percent solid matter is subtracted from 100% to give percent porosity: Porosity = 100% - (BI/BJ x 100%) SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  14. POROSITAS TANAH An undisturbed oven-dry soil, BD of 1.3 g/cu cm, consists of average mineral composition (PD 2.65 g/cu cm). Find its % Porosity: Porosity = 100% - (1.3 g/cu cm/2.65 g/cu cm x 100%) Porosity = 100% - (0.49 x 100%) = 100% - 49% = 51% SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  15. POROSITAS TANAH Pertanyaan: Which has greater porosity, Sand or Clay? Answer: Clay at about 50%; Sand is lower at about 30% Why? SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  16. TEKSTUR & PORI TANAH SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  17. TEKSTUR & PORI TANAH • Why, then, does water move through sandy soil very rapidly, but moves slowly into clay ? SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  18. TEKSTUR & PORI TANAH This is explained by the physical property Permeability SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  19. PERMEABILITAS Permeability – the ease with which air, water, and roots move through soil - Depends on number, size, and continuity of pores - Liken to a maze SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  20. Fine-textured soils would be impermeable if not for: Soil Structure PERMEABILITAS SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  21. STRUKTUR TANAH Structure – the way soil particles clump together into large units called aggregates or peds SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  22. STRUKTUR TANAH Structure can alter the effects of texture • e.g. a fine-textured silty clay with good structure can be permeable! SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  23. STRUKTUR TANAH • Structure is classified by three groups of traits: • Type – refers to shape of aggregates e.g. Granular, Platy, Blocky, Prismatic, Columnar • Class – refers to size of peds e.g. very fine, fine, medium, coarse, very coarse • Grade – refers to strength and distinction of peds e.g. weak/not visible vs. strong/easily distinguished SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  24. PEMBENTUKAN STRUKTUR TANAH Two-step formation: • Individual soil particles loosely aggregate • Weak aggregates are cemented to strengthen - clay - iron oxides - organic matter - microorganism gums SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  25. KONSISTENSI TANAH Soil Consistence – the behavior of soil when pressure is applied; measured at three different moisture levels: Wet, Moist, Dry (fig 4-15, p. 59) Soil Tilth – ease of tillage, seedbed preparation, and seedling/root movement Compaction – results from pressure applied at the soil surface SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  26. PELUMPURAN TANAH Pelumpuran, BongkahandanKeraktanah: Puddlingoccurs when pressure is applied to very wet soils (esp. plowing) Crusts occur when bare soil is struck by raindrops; disperses soil then dries to a hardened crust SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  27. SIFAT OLAH TANAH Memperbaikisifatolahtanah: Best accomplished by improving structure - tilth relates to texture, structure, permeability, and consistence; however, TeksturdanKonsistensisangatsulitdiubah, sehinggaperbaikansifatolahtanahdilakukandenganmemperbaikistrukturdanmenghindaripemadatantanah SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  28. CADAS TANAH Liang-liangtanah– continuous macropores leading from surface to deep subsoil Cadas Tanah – any layer of hardened soil; includes: - claypans = cadasliat - fragipans (clays) = cadasliatkeras - plinthite(didaerahtropis) - caliche (Ca cemented) SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

  29. TEMPERATUR TANAH Temperatur TANAH (dipengaruhiolehwarnatanah, teksturdan BOT) Warna Tanah: Munsell soil color chart Hue, Value, Chroma Misalnya: 10YR 3/6 SUMBER: www.swac.umn.edu/classes/soil2125/.../l02b.ppt‎

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