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INTEGRATED SCIENCE
Posted by Chester Morton / Saturday 14 May 2016 / No comments
Soil science
SOIL SCIENCE
Soil is the loose part of the earth’s crust that can support
plant growth.
Importance of soil
It serves as habitat
for some living organisms
It provides the
nutrients requirement of plants
It supports plants
growth
Factors that influence the formation of soil
· Topography of
the land
· Climate
· Living
organisms
· Time
· Human
influence
· Parent rock
materials
COMPONENTS OF SOIL
Mineral components (it consists of salt, silt and clay)
Soil water
Soil air
Organic matter
Soil Living organisms
PHYSICAL PROPERTIES OF SOIL
Soil Texture: This refers to the degree of coarseness or the fineness of the soil particles
Soil Structure: This refers to the way in which the different
soil particles are arranged. It gives the physical appearance of the soil.
Water Holding Capacity: This is the measure of the ability of soil to retain water. It determines drainage through the soil.
Characteristics
|
Sand
|
Clay
|
Loam
|
Particle size
|
Large
|
Small
|
Intermediate
|
Texture
|
Coarse- feels gritty when wet
|
Fine- feels sticky when wet
|
Intermediate
|
Air Space
|
Large
|
Small
|
Intermediate
|
Water Retaining Capacity
|
Low
|
High
|
Intermediate
|
Porosity
|
High
|
Low
|
Intermediate
|
SOIL PROFILE
This refers to the vertical cross-section of
the soil which shows all the layers of the soil particles.
Characteristics of each layer/ horizon
1.
Topsoil/Horizon A
It is rich in organic matter and microbes
It is dark in colour
Nutrients here can be leached to the sub-soil
It is usually less thick than sub-soil
2. Sub-soil/
Horizon B
It contains less organic matter and microbes
Relatively thicker and less dark than the top-soil
It is usually reddish-brown in colour
Nutrients leached are deposited here
3. Horizon C
It contains no organic matter and microbes
It contains weathered materials
Soil minerals occur in this layer
4. Horizon D
It contains rocks which have not undergone weathering
It contains no organic matter and microbes
IMPORTANCE OF SOIL PROFILE
· It helps to
determine the nutrient content of a soil
· It helps to
determine the soil type of a particular land
· It helps the
farmer to determine the crop suitable for a particular land
· It helps to
determine the susceptibility of a land to soil erosion
· It enables
the farmer to know the type of implement to use.
SOIL FERTILITY AND SOIL PRODUCTIVITY
A fertile soil is one that can provide adequate conditions
and nutrients for effective growth of plant.
Features of a fertile soil:
It is rich in soil nutrients and organic matter
It must contain useful soil organisms
It must have a good water holding capacity
It must have a suitable Ph
The texture must be loamy
SOIL FERTILITY
This refers to the ability of soil to
provide physical conditions and nutrients required for effective growth of a
plant.
SOIL PRODUCTIVITY
This refers to the ability of soil to
provide desired yield in the cultivation of a given plant when properly
managed.
LOSS OF SOIL FERTILITY
The following are some of the ways
through which a soil can lose its fertility:
Crop removal
Leaching
Erosion
Bushfires
Overgrazing by cattle and other farm animals
Poor farming and tillage methods
Surface mining and quarrying
MAINTENACE OF SOIL FERTILITY
In order to avoid soil losing
its fertility, the farmer can undertake or carry out any of the following to
preserve the fertility of the soil.
Growing of cover crops
Practicing crop rotation
Application of organic and inorganic fertilizers
Adding lime top the soil
Practicing fallow cropping
Strip cropping: This refers to the planting of crops along
the contours of slope
Terracing: This refers to leveling of hilly areas in the
form of steps.
Practicing mixed farming and mixed cropping
PLANT NUTRIENTS
These are substances that plants require in
various quantities in order to grow. There are two types of nutrients. These
are macronutrients and micronutrients.
a.
Macronutrients: These are the nutrients required in large amount for
proper growth of the plant. Example Nitrogen (N), Potassium (K), Phosphorus
(P), Calcium (Ca), Magnesium (Mg) and Sulphur (S).
b.
Micronutrients: These are the nutrients required in small amounts to
support the growth of the plant. Example Boron (B), Manganese (Mn), Chlorine
(Cl), Zinc (Zn), Copper (Cu) and Iron (Fe).
SOME ESSENTIAL NUTRIENTS FOR PLANT GROWTH
Nutrients
|
Functions
|
Deficiency
|
Nitrogen
|
Formation
of proteins and chlorophyll
|
-
Small sized plants
-
Poor development
-
Yellowing of leaves
|
Phosphorus
|
Formation
of energy compounds and acts as a buffer in the cell sap
|
-
Poor root development
-
Small sized plants
-
Mottling (colours of different shades)
|
Potassium
|
Formation
of cell membranes and regulates certain metabolic processes in the cell
|
-
Red leaf coloration
-
Weak plants
-
Poor growth
|
Magnesium
|
Formation
of chlorophyll
|
Yellowing
of leaves
|
Iron
|
Formation
of chlorophyll
|
Yellowing
of leaves
|
Sulphur
|
Formation
of protein
|
Slender
stems and yellowing of leaves
|
Calcium
|
Formation
of cell walls
|
-
Stunted growth
-
Poor roots development
|
Labels:
INTEGRATED SCIENCE
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