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