CIRI-CIRI FISIKA TANAH

CIRI-CIRI FISIKA TANAH
SUMBER:

SUMBER: www.swac.umn.edu/classes/soil2125/.../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 SUMBER:

Smaller particles – larger internal surface area
EFEK UKURAN PARTIKEL TANAH Smaller particles – larger internal surface area SUMBER:

More pores – micropores Larger pores – macropores
EFEK UKURAN PARTIKEL TANAH More pores – micropores Larger pores – macropores SUMBER:

SEPARAT TANAH SAND 2.00 – 0.05 mm SILT 0.05 – mm CLAY < mm SUMBER:

Twelve Textural Classes Textural Triangle KLASIFIKASI TEKSTUR TANAH
SUMBER:

DENSITAS (KERAPATAN): MASA per VOLUME D = M V
DENSITAS & PERMEABILITAS TANAH DENSITAS (KERAPATAN): MASA per VOLUME D = M V SUMBER:

DENSITAS & PERMEABILITAS TANAH
Dua macam kerapatan (densitas) dalam tanah: Particle Density – PD : Bobot Jenis (BJ) Bulk Density – BD: Bobot Isi (BI) SUMBER:

BJ rata-rata tanah ~ 2.65 g/cm3 BI average range from 1.0 – 1.8 g/cm3
DENSITAS & PERMEABILITAS TANAH BJ rata-rata tanah ~ 2.65 g/cm3 BI average 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 = g/cm3 500 cm3 SUMBER:

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:

POROSITAS TANAH Water Volume to Core Volume wet weight (g) – dry weight (g) Porositas = x 100% soil volume (cu cm) SUMBER:

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 cu cm Note: the unit cancellation is made possible by the metric system which defines 1 cu cm of water as weighing 1g. SUMBER:

POROSITAS TANAH Bobot Isi (BI) vs. Bobot Jenis (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:

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:

POROSITAS TANAH Pertanyaan: Which has greater porosity, Sand or Clay? Answer: Clay at about 50%; Sand is lower at about 30% Why? SUMBER:

TEKSTUR & PORI TANAH SUMBER:

TEKSTUR & PORI TANAH Why, then, does water move through sandy soil very rapidly, but moves slowly into clay ? SUMBER:

TEKSTUR & PORI TANAH This is explained by the physical property Permeability SUMBER:

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:

PERMEABILITAS Fine-textured soils would be impermeable if not for: Soil Structure SUMBER:

STRUKTUR TANAH Structure – the way soil particles clump together into large units called aggregates or peds SUMBER:

STRUKTUR TANAH Structure can alter the effects of texture e.g. a fine-textured silty clay with good structure can be permeable! SUMBER:

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:

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:

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:

PELUMPURAN TANAH Pelumpuran, Bongkahan dan Kerak tanah: Puddling occurs 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:

SIFAT OLAH TANAH Memperbaiki sifat olah tanah: Best accomplished by improving structure - tilth relates to texture, structure, permeability, and consistence; however, Tekstur dan Konsistensi sangat sulit diubah, sehingga perbaikan sifat olah tanah dilakukan dengan memperbaiki struktur dan menghindari pemadatan tanah SUMBER:

CADAS TANAH Liang-liang tanah – continuous macropores leading from surface to deep subsoil Cadas Tanah – any layer of hardened soil; includes: - claypans = cadas liat - fragipans (clays) = cadas liat keras - plinthite (di daerah tropis) - caliche (Ca cemented) SUMBER:

TEMPERATUR TANAH Temperatur TANAH (dipengaruhi oleh warna tanah, tekstur dan BOT) Warna Tanah: Munsell soil color chart Hue, Value, Chroma Misalnya: 10YR 3/6 SUMBER:

CIRI-CIRI FISIKA TANAH

Similar presentations

Presentation on theme: "CIRI-CIRI FISIKA TANAH"— Presentation transcript:

Similar presentations

About project

Feedback

Log in

Auth with social network:

CIRI-CIRI FISIKA TANAH

Similar presentations

Presentation on theme: "CIRI-CIRI FISIKA TANAH"— Presentation transcript:

Similar presentations

About project

Feedback