SAINS TANAH ASAS SST 3005 - Universiti Putra Malaysiavodppl.upm.edu.my/uploads/docs/Lect 1-2.pdf ·...
Transcript of SAINS TANAH ASAS SST 3005 - Universiti Putra Malaysiavodppl.upm.edu.my/uploads/docs/Lect 1-2.pdf ·...
SAINS TANAH ASAS SST 3005
(Fundamentals of Soil Science)
Kod Kursus : SST 3005 Ditawar kepada : Pelajar Ijazah Ditawar pada : Semester 1 dan 2
Pra-Syarat : tiada
Kuliah 1 dan 2
• Course objective: To give an understanding of the
fundamentals of Soil Science and its relationship with crop production, and prepare students for higher levels of soil science courses.
• Sinopsis Kursus: Kursus pengenalan kepada sains tanah yang meliputi pembentukan tanah, sifat fizik, kimia dan biologi tanah, pemakanan tumbuhan dan baja, survei, pengkelasan dan penilaian tanah. (A basic soil science course dealing with soil formation, physical, chemical and biological properties, plant nutrition and fertilizers, soil classification, survey and evaluation)
Soil Science “A branch of science that is related to soil
formation, classification, mapping, soil physical, chemical and biological characteristics and soil fertility; including the use and management of the soil in relation to its characteristics”.
Importance of Soil (soil funtions)
• The most important natural resource for human to live; human development is closely related to soil
• Soil is important for agricultural activities to supply food, clothes and protection for human
• Disposal of domestic and industrial wastes
• Habitat for soil organisms • Support plant life
• Recreation • Ground for construction of buildings
and and roads • Source of materials with economic
value, e.g. kaolin (clay) for pottery
Regolith and Soil Soil: • loose material on top of the rock (Figure 1.1) • may be shallow or tens of meter thick • there may be weathered material from the
rock below or transported material deposited on the rock
Regolith is divided into 2 parts: • The upper part (1 -2 m): Containing higher
organic matter content; from plant residues and roots which has experienced the process of decomposition by soil organisms and transportation processes, This part is called ‘SOIL’ (Horizon A dan B)
• The lower part: less organic matter content and less biological activities. This part is called the ‘PARENT MATERIAL’ (Horizon C)
• The product of activities at the top forms soil layers called HORIZON (Figure 1.1).
• Each horizon ha different characteristics. The vertical section of the soil showing different horizons according to the depths is called ‘SOIL PROFILE’ (Figure 1.2)
Soil Profile
SOIL PROFILE • Horizon A: higher organic matter
contents and darker in colour than the horizons below
• Horizon B: normally higher clay contents, with clear structure
• Horizon A + B = SOLUM • Horizon C: parent material, i.e.
weathered rock
Soil is formed from ROCKS. Rocks and soil form the earth crust or the LITHOSPHERE
• Soil is found on top of the earth’s crust (Figure 1.3)
Earth’s crust, l 5 - 70 km Consists of two parts : • Sial - silicon-aluminum • Sima : silicon - magnesium (Rajah 1.4) Composition of the earth’s crust • Solids: rocks and soil • Elements that form minerals and in turn
form the rocks
Main elements in the the earth’s crust Percent
Oxigen 47.0
Silicon 28.0 Aluminum 8.0 Iron 5.0 Calcium 3.5 Sodium 2.5 Potassium 2.6 Magnesium 2.0 Others 1.1
46.6%
27.7%
8.1%5.0% 3.6% 2.8% 2.6% 2.1%
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
O Si Al Fe Ca Na K Mg
Percentages of the Eight Most Common Elements in the Earth's Crust by Weight
SOIL COMPOSITION
4 main components • Non-organic or mineral • Organic matter • water • air (Figure 1.5).
Soil solids Sand (Quartz) – main component
Other minerals, e.g. mica, feldspar and other secondary minerals
Organic matter
The air and water contents changes according to the level of soil moisture. At the optimum level of plant growth, the air and water contents are the same, i.e. 25%.
• Soil is formed from rocks and
minerals through physical and chemical weathering.
2. Minerals and Rocks
MINERALS Definition: • A mineral is an element or a chemical
compound, non-organic and formed naturally, with a certain atomic composition and structure.
• Divided into 2 types of minerals 1. primary minerals : formed from
crystallization of magma 2. secondary minerals : formed from
weathering of primary minerals
Common rock forming minerals
Olivin
Amphibole
Pyroxene
Mica, Feldspar
Quartz
MINERAL FORMULA KETAHANAN LULUHAWA
Quartz SiO2 Paling Tahan Luluhawa
Paling Mudah Diluluhawa
Microkline KAlSi3O8
Ortoklas KAlSi3O8
Biotite KAl(Mg,Fe)3Si3O10(OH)2
Albit NaAlSi3O8
Hornblen Ca2Al2Mg2Fe3Si6O22(OH)2
Augite Ca2(Al, Fe)4(Mg, Fe)4Si6O24
Anortit CaAl2Si2O8
Olivin (Mg, Fe)2SiO4
Method of identification of primary minerals
Physical properties:
Colour
Streaks
Lustre
hardness
Cleavage
Table 2.2 Secondary minerals
MINERAL FORMULA RESISTANCE TO WEATHERING
Goetite FeOOH Most resistant
Least resistant
Hematite Fe2O3
Gibbsite Al2O3.3H2O
Clay minerals Silicate Al
Dolomite CaCO3
Calcite CaCO3
Gipsum CaSO4
Silicate Al
Kaolinite Illite
Chlorite
Secondary minerals as seen under SEM