Sandy soils of west coast SouthAfrica Physical & human attributes

Physical attributes (soil) Sandy soil of South African West Coast is

characterized by a low soil organic carbon, a low cation exchange capacity, a high risk of nutrients leaching, low structural ability and a high sensitivity to erosion and to crusting.

Both chemical fertility and physical stability are weak in this soil. The characteristics are due to their sandy texture, low reactivity of their clays, and to climatic conditions that often accompany the soil.

The soil

Due to dominant minerals such as (quartz, kaolinite, iron, and aluminium oxides) and the type of soil texture, the role of organic matter is fundamental in this area.

The biological processes are crucial to sustain the fertility of the soil as they control carbon and nitrogen fluxes.

Due to low rainfall the soil of the area is composed of an assemblage of solid particles and voids.

Climate Has climate conditions of a desert r semi desert

area. Surrounding conditions are affected by the cold

banguela current The cooling and upwelling of the Benguela

current brings moisture-laden sea winds to the west coast. The effect of the cold, upwelling Benguela current and the constant, strong South Atlantic high-pressure system are two of the main causes for the present aridity along the west coast.

The rainfall and moisture

The rainfall regime in semi desert area is characterised by low irregular, unpredictable precipitation often concentrated in few rainstorms. Several years may ellapse between successive rainfalls.

The area experiences low air humidity. High solar radiation and high air temperatures lead to enhanced evaporation rates.

Rainfall and moisture Port Nolloth normally receives about 50mm

of rain per year and because it receives most of its rainfall during winter it is considered to have a Mediterranean climate.

The chart below shows the average rainfall values for Port Nolloth per month. It receives the lowest rainfall (0mm) in January and the highest (10mm) in May.

Port Nolloth is one of the towns in the West coast .

Table shows monthly rainfall in Port Nolloth

Average rainfall (mm)

010

0

J

F

M

A

M

J

J

A

S

O

N

D

The temperature

Air temperature in arid zones is generally high and may show significant variations between day and night. Summers are hot, often unbearably so as the mercury reaches up to 40 and even 50°C in some areas of the west coast. Autumn is the mildest season with temperatures ranging from 14 to 25°C.In winter temperatures rarely reach above a high of 20°C.

Temperature The monthly distribution of average daily

maximum temperatures shows that the average midday temperatures for Port Nolloth range from 20°C in July to 27.1°C in January. The region is the coldest during July when the mercury drops to 8°C on average during the night. The chart below is an indication of the monthly variation of average minimum daily temperatures.

Graphs of day and night temperatures in Port Nolloth

Average midday temperature (°C)

02

8

20

J

F

M

A

M

J

J

A

S

O

N

D

Average night-time temperature

(°C)

01

5

8

J

F

M

A

M

J

J

A

S

O

N

D

Topography Great Escarpment and the Drakensberg

mountains provide the physical barriers which determine the climate and vegetation of much of the livestock growing regions of South Africa.

In geological time, several phases of uplifting, erosion and deposition have created complex landforms determined by the underlying geology

The vegetation The primary vegetation of the west coast

area of South Africa is mainly fynbos, which grows on fairly nutrients-depleted mostly sandstone-derived acidic soils. Fynbos is technically described as a vegetation that has more than 5% cover of Restios, exists in a fire controlled ecosystems characterised by significant winter rainfall, nutrient-poor soils, and floristic richness and endemism

Human attributes

Human attributes The South African West coast is characterized by several human attributes. Attributes such as the following: •Exploitation of marine invertebrates for example games such as shell fishing. Human settlement • excessive shell fishing

Human attributes •Stone knapping•Exploitation of coastlines from building holiday houses (hotels)Subsistence harvesting, human partake in the activity of harvesting in the area that often leads to the depletion of the marine coastlines due to excessive exposure to such activities since coastline are susceptible to such pressure exertion.

Human attributes

Windsurfing on the Langebaan lagoon Humans keep farms for cattle and sheep

large and farms are mainly livestock. The farmers closest to the Swartland also

produce wheat .it is an important source of income.

Wine producing farms exploiting the organic material of the area particularly grapes.

Conclusion Presence of resorts and hotels in the area

leads to the exploitation of the surrounding organic matter such as plants and the marine organisms .

Large farming activities lead to live stock overgrazing the grass and leading to erosion conditions and desert like conditions.

Some human games are not environment friendly.

Conclusion Therefore it appears that human beings have

more of a bad contribution to the sandy South African West coast area, than good contributions.

One of the important environmental challenges arising from growing urban, agricultural and industrial development is the degradation of soil resources.

The processes of soil degradation are closely linked to unfavourable alterations in the physical, chemical, biological and hydrological activities and mismanagement by humans.

Conclusion If the consequences of these activities are

not adequately addressed, the stability of soil’s ecosystem for the next generation will be jeopardized.

A vast area of the earth is characterized by arid and semiarid conditions.

Soil quality, its role in human life and its sensitivity to human impacts in these areas is very different from those in other climatic zones.

Conclusion Intensified use due to increased population

pressure has already resulted in and aggravated serious problems such as salinization, alkalinization, nutrient depletion, desertification, erosion and other forms of land degradation.

Thus, it is very useful to take a look at the relationship between soil and man in these areas to assess and anticipate the interdependence of soil and society