ARCHITEKTUR & SIFAT FISIKA TANAH WARNA TANAH Valuable clues to the nature of soil properties and conditions. Munsell Colour Charts Hue (colour) Chroma (intensity) Value (brightness) Value and chroma are assessed from each hue page (p. 122). SUMBER: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20II%202008.ppt
ARCHITEKTUR & SIFAT FISIKA TANAH. WARNA TANAH Valuable clues to the nature of soil properties and conditions. Munsell Colour Charts Hue ( colour ) Chroma (intensity) Value (brightness) Value and chroma are assessed from each hue page (p. 122). - PowerPoint PPT Presentation
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
ARCHITEKTUR& SIFAT FISIKA TANAH
WARNA TANAHValuable clues to the nature of soil properties and conditions.
Munsell Colour Charts
Hue (colour)Chroma (intensity)Value (brightness)
Value and chroma are assessed from each hue page (p. 122).
TEKSTURBased on sand, silt and clay fraction (see earlier notes) Effect of exposed surface area on other soil properties
1. Increases capacity to hold water2. Nutrients and chemicals retained more effectively3. Release of nutrients from weatherable minerals faster 4. Electromagnetic charges. Increases stickiness and aggregation.
Not a lot of clay/organics are required to impart these featuresBest soils are usually those with relatively equal proportions of the different soil texture classes.
Metode Hidrometer2. Place measured quantity of soil in a stirring cup and mix
with deionized water and a dispersing agent [eg.(NaPO3)6]
3. Transfer to settling cylinder, add deionized water to a measured level (eg. 1L) and record the temperature of the suspension.
4. Insert plunger and mix by pulling plunger up with short jerks. Record the start time with second accuracy.
5. Gently insert the hydrometer and record its reading aftera set time (eg. 40 seconds). Correct for temperature.Repeat 4&5 three times or more to get a good average.
6. After 3 hrs (less in our case), take another reading with the hydrometer.
7. Calculate % sand, silt, and clay, and determine the soil textural class
Struktur Tanah Mineral- aggregates or peds- affects water movement, heat transfer, aeration and porosity- affected by human action (logging, grazing, tillage, drainage,
manuring, compaction and liming)1. Spheroidal (granular or crumb)
- most common in A Horizons2. Plate-like
- most common in E Horizons- due to compaction or inherited from parent material
3. Block-like- common in B Horizons of humid regions
4. Prism-like- common in B Horizons of arid and semi-arid regions
p. 134SUMBER: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20II%202008.ppt
Analysis of structure in the field1. Type of peds2. Relative size of peds (fine, medium, coarse)3. Distinctness or development of peds (weak, moderate, strong)
*Difficult to assess when the soil is wet*
Soil Particle DensityDp = Mass per unit volume of soil solidsMeasured in Mg/m3
Particle density is not affected by pore space, because it does nottake them into account.
Mineral soils mainly in the 2.60 to 2.75 Mg/m3 rangeUp to 3.00 Mg/m3 if minerals very dense (eg. magnetite, hornblende) Organic matter has a much lower particle density (0.90-1.30 Mg/m3)
Db = Mass per unit volume of dry soil• Soil corers used to obtain known volume
without disturbance• Soils are then dried and weighed*Db includes both solids and pores*
• Bulk density is affected by soil porosity• Highly porous soils have a low bulk
density
Sandy soils have a higher bulk density (larger pores, but lower porosity overall)than silty or clayey soils.
• Well-sorted (poorly-graded) soils generally have lower bulk density• Well-graded soils generally have higher bulk density• Tightly-packed soils have higher bulk density• A typical, dry medium-textured soil weighs 1250 Kg/m3 or 1.25 Mg/m3
Efek Pengolahan Tanah terhadap AgregasiJangka Pendek: • Improvement in aggregation if done on moderatelydry soil• Breaks up large clods, loosening soil and increasing porosity• Incorporates organic matter into the soil
Jangka Panjang:• Loss of aggregation• Enhanced oxidation of organic material reduces aggregation• Loss of macroporosity occurs if tillage is carried out in a wet
soil (puddled)• Effect less pronounced where Fe & Al oxides plentiful