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Social sciences:


Grade 8

Natural resources

Module 8

Agriculture, forrestry and alien invaders


The greatest damage that humans inflict on the earth – and by implication, the greatest threat that humanity poses to its own future survival – is through the practice of agriculture. Huge areas of the planet’s natural terrestrial ecosystems have already been destroyed and replaced with artificial agricultural systems, greatly reducing or even negating the ability of the land to control and influence its own climate and chemistry.

Of South Africa’s surface area of some 120 million hectares, about 85 per cent is used for agriculture and forestry. Only 45 per cent of the country receives more than 500 mm rain annually – the generally accepted minimum for dryland crop production – and only 12 per cent is suitable for cultivation. The rest is mainly natural veld used for grazing.

Because of the lack of suitable planning in the past and gross over subsidisation – often to win political favour – much prime arable land has been irrevocably lost to urbanisation, mining (particularly on the Witwatersrand and in Mpumalanga) and other activities. Also, injudicious management and cultivation of crops not ecologically suited to conditions have caused widespread degradation in the form of soil erosion and desertification. Annual soil losses, mostly through poor land husbandry practices, are estimated at between 300 and 400 million tonnes annually.

The question of existing land ownership in agriculture is being addressed as a matter of urgency by the Government of National Unity. Before the 1994 elections, an estimated 50 000 white farmers – many of them heavily subsidised for political reasons and extensively in debt to an amount of R14 billion – owned some 85 million hectares, of which about 14,3 million were arable. The 700 000 black farmers in the former “homeland” areas had access to only some 15 million hectares, of which only 2,3 million were arable.

Activity 1:

To identify the poor management of agricultural land and suggest precautionary measures

[lo 3.3]

1. Underline the correct words. Explain your choice.

  • Livestock must be decreased/increased to remain within the capacity of the land.
  • The simultaneous cultivation of crops and the keeping of livestock must be encouraged/discouraged .

2. Why is it necessary that the use of fertilizers, insecticides and weed killers should be strictly controlled? Give your opinion.

3. In what respect does urbanisation contribute to the destruction of agricultural land?


Forests are an integral part of Earth’s life-support systems, playing a crucial role in regulating the atmosphere and climate through their ability to store carbon and drive local hydrological cycles. They protect soils from excessive erosion, regulate run-off and reduce the effect of floods and consequently silt loads in rivers. Natural forests are usually highly diverse ecosystems, supporting millions of species and providing human beings with a wealth of benefits. They are also an important part of the resource base for tourism and recreation, and have an inestimable cultural value as a source of beauty, contemplation and inspiration that finds expression in art, music, literature, dance and religion.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Geography grade 8. OpenStax CNX. Sep 11, 2009 Download for free at http://cnx.org/content/col11036/1.1
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