UNITS

• OVERVIEW 
• Unit 1 Agricultural resources 
• Unit 2 Soil conservation and management 
• Unit 3 Water management 
• Unit 4 Agricultural pollution 
• Topic questions 

TOPIC 3: SUSTAINABLE NATURAL RESOURCE UTILISATION

Overview

The two most important natural resources in agricultural production are soil and water, therefore they have to be used in a sustainable way.

What you will cover in Topic 3

Unit 1: Agricultural Resources

1.1 Natural resources and agricultural resources

Natural and agricultural resources

1.2 The pressure that a growing population exerts on natural resources
1.2.1 Population growth
South Africa’s annual population growth rate is between 2% and 2,5%: Nearly a million people per year → more food is needed, using the same amount of soil and water → puts pressure on natural resources.

Pressure on the soil
Soil is a complex mixture of organic and inorganic matter that takes thousands of years to form = a non-renewable resource. In addition:

• Only a small part of the Earth’s surface can be used for agriculture.
• Because of increasing demand for food, traditional farming methods (e.g. 10- year fallow period) have been replaced with use of chemicals and fertilisers non- sustainable practices because they lead to soil degradation.

Pressure on water

Only about 0,36% of the total amount of water on Earth is available to meet human needs

70% of the surface of the earth is covered with water:

• 97% is seawater
• 3% of the water on the planet is fresh
• 79% of fresh water is frozen in the polar caps and the ice glaciers.
• 20% is hidden away in underground water sources, (e.g. aquifers and wells)
• Only about 0,036% of the total amount of water on the planet is found in surface water sources such as rivers, lakes and dams.

Increased pressure on water due to:

• population growth and the resulting need for increased agricultural output
• climate change.

Many countries in Africa, including SA, will shift from water surplus to water scarcity as a result of population changes alone between 2010 and 2025.

1.3 Sustainable use of natural resources in agriculture

• In agriculture, soil and water are strongly linked. Good soil conservation practices conserve water; good water conservation practices conserve the soil.
• Only a small part of the soil and water can be used for agriculture → both must be used in a sustainable way. In addition:
  • Water is in short supply in most of southern Africa.
  • Soil can easily be degraded, eroded or washed into the sea.
• Link in modern agriculture between natural resources and food security → if natural resources are compromised, the world population will not have food security.
• The sustainable utilisation of natural resources in agriculture involves the following:
  • Conserving the soil so that rain does not wash it into rivers or dams, wind does not blow it away and chemicals (e.g. fertiliser and pesticides) do not pollute it.
  • Conserving water by checking tanks for leaks, and making sure it is not polluted by agricultural chemicals or animal waste.
  • Managing the animal waste on the farm and using it to enrich the soil.
  • Properly planning farm processes, such as ploughing and irrigation, so that they do not have a negative impact on the environment and natural resources.

Unit 2: Soil Conservation and Management

2.1 Soil degradation
Overgrazing = about 35% of soil degradation. Mismanagement of arable land = 35%.

• Soil degradation = any process that causes the condition of the soil to degrade or lose its nutrients:
  • loss of the quality of the soil → no longer a good medium for plants to grow in
  • the loss of the soil itself, through soil erosion.
• Soil conservation = the process to stop the degradation of soil and repair the damage so that the condition of the soil improves and is maintained.

2.2 The types and processes of soil degradation
Soil degradation can happen through:

• loss of soil quality
• loss of soil through erosion.

2.2.1 Loss of soil quality
Two factors play a role in the quality of soil: soil nutrients and soil structure. So, anything that affects soil nutrients of soil structure can result in soil degradation. The quality of the soil can be degraded or decreased in three ways:

• physical degradation
• biological degradation
• chemical degradation.

Physical degradation
Happens when the structure of the soil is damaged by:

• wrong cultivation methods, e.g. using the wrong implement
• ploughing when the soil is too wet or too dry

Ploughing when the soil is too wet

• Dense layers of tightly packed soil (plough bank / smear layer) form at the bottom of the layer that was ploughed.
• When it is compacted → contains less air → can store less soil water → plant roots cannot penetrate layers of compacted soil → plant growth is decreased: crop yields are negatively affected.
• The most common cause of compaction = tractors, harvesting machinery and implement wheels that travel over wet soil.
• Wet soil compacts more readily, because the water allows the soil particles to be rearranged more easily.
• Some soil types also compact more easily than others: soil containing more organic material compacts less easily.

Avoiding and fixing compaction
To avoid compaction:

• Don’t drive on wet soil and don’t use high compaction tools, such as disc ploughs and heavy tractors while soil is wet.
• If soil is compacted:
  • leave the field for a season or two to rejuvenate
  • use a combination of reduced or no tillage and reduce tractor traffic
  • ‘deep rip’ (ploughing to a greater depth) to minimises the effects of compaction, but don’t drive on the field again if the soil is wet: this will settle the compacted layer again.

Avoiding physical degradation
Inspect soil regularly using a spade to see deeper layers.

Avoiding biological degradation

• Always use cuttings from registered nurseries.
• Use only certified propagation material.

Avoiding chemical degradation

• Use biodegradable herbicides and pesticides
• Use the natural enemies of the particular pest.

Ploughing when the soil is dry

• Ploughing when the soil is too dry will leave big clods in the soil.
• These clods are difficult to break when a new seedbed for the next crop is created.

Biological degradation
This is caused by:

• Cuttings from unregistered nurseries, or illegally imported plants and seeds, can spread pests (eelworm) or pathogens.
• Agricultural practices such as tillage and increasingly converting areas with natural vegetation to agricultural land.
• These practices cause the disappearance of natural soil bacteria and microbes.
  • The fertility of the soil decreases.
  • Replacement of primary plant communities (climax) by secondary communities.

Chemical degradation

• Due to use of chemicals e.g. Atrazine (herbicide) to kill weeds and pests.
• Chemicals have to be leached from the soil before next crop is planted.

2.2.2 Loss of soil through soil erosion
Soil erosion is the loss of the soil itself through the action of wind or water. Soil erosion causes great damage to the land, because it removes the topsoil. Without topsoil

• crops don’t grow well = poor harvests
• grazing doesn’t grow well = animals become thin → do not produce much milk and many young animals die.
• not enough plants to hold the soil when it rains, or when the wind blows = more soil is carried away → fertile areas soon become deserts → no food can be produced.

Thousands of tons of fertile topsoil are transported by the wind and water to rivers, dams and the sea. This causes siltation, which leads to floods.
Causes of soil erosion

• Removal of plant cover: Farming methods that remove plant cover are –
  • ploughing
  • overgrazing
  • veld burning
  • deforestation.
  • Slope: The steeper the land, the greater the rate of erosion.

Warning signs

• muddy water in streams and rivers
• dams filled with mud
• plants with bare roots
• dust storms
• new soil deposits (water carries soil from higher ground to lower ground, new soil deposits in the lower parts means that soil erosion has taken place higher up and washed the soil down)
• pedestals
• bare ground
• deep cattle and foot paths.

Effects of soil erosion

• The topsoil is removed, which decreases fertility. Fertiliser has to be added.
• It reduces the amount of water that sinks into the soil.
• The cost of farming increases, which leads to increase in food prices.
• Damage to infrastructure and the environment:
  • sediment on roads, waterways and rivers (due floods)
  • fertilisers and pesticides washed into rivers.

How to prevent soil erosion on a slope
Note: Farmers should not use slopes greater than 15º for growing crops, because it is difficult to prevent erosion on slopes that have more than a 15º gradient. There are five ways to hold the soil on slopes:

1. Contour ploughing:
   • On a slope of 0º–3º by ploughing along the slope.
2. Vegetation strips:
   • On slopes of 3º–15º. Plant strips of 1–8 m wide along the contours between crop areas. The strips stop runoff and hold the soil. After a few years, the rain will move the soil down the slope between the strips and the slope between the strips will start levelling.
3. Stone banks:
   • On slopes of 3º–15º. Pile stones along the contours. Crops are planted along the contours between the stone banks. Stone banks are especially useful:
     • when the soil contains many stones that hinder ploughing or planting
     • to repair land where there is erosion
     • in low rainfall areas to increase the amount of water that goes into the soil.
4. Contour banks:
   • On a slope of 3º–15º. Difficult to construct, so farmers should consult an agricultural extension officer. Farmers need to work together to plan a system for the entire area. A contour bank system consists of three parts:
     • the contour banks – a ditch with a bank or wall of soil on the downward slope
     • the cut-off drain – it catches the water that runs off the land above the field, which gives the water time to soak into the soil
     • the grass waterway – it carries any extra water away from both ends of the contour banks and the cut-off drain.
5. Terraces:
   • On slopes steeper than 15º. Terraces are steps that are cut into the slope. Crops are grown on the flat part of the step and the soil is supported on the upright part of the step by grass, trees or stones. Terraces flatten out. Plan where to put the cut-off drain and terraces before building terraces.

2.3 Impact of soil degradation on agricultural productivity
Soil degradation leads to loss of fertile soil for food production:

• The global loss of productive land through soil degradation = 5–7 million ha per year. Every year 25 000 million tons of topsoil is washed away (according to FAO).
• Worldwide, soil erosion puts the livelihoods of nearly 1 000 million people at risk.
• In SA 300–400 million tons of soil is lost every year. To replace the soil nutrients with fertiliser would cost R1 000 million.

2.3.1 Other impacts of soil degradation on agricultural productivity
Agricultural activities themselves lead to loss of soil:

• for every ton of maize, wheat, sugar or other agricultural crop that is produced, South Africa loses an average of 20 tons of soil.
• Soil erosion:
  • difficult to plough land
  • disturbs or removes seeds, leading to crop loss
  • fertiliser and pesticide lost – replaced at great cost
  • soil quality changes: if the lighter soil particles are washed away, only the bigger particles remain, affecting the water-holding ability of the soil and making it less able to withstand drought → can result in the type of soil changing.
  • Soil deposits: slow the emergence of new plants after germination; may even stop germination.
• Sedimentation fills rivers: rivers hold less water and flood easily.

 Unit 3: Water Management

3.1 Water quality

• Water quality is measured according to the physical, chemical, biological and aesthetic properties of water, based on what the water is to be used for.
• In SA, the Department of Water Affairs (DWA) is responsible for water quality. It has to ensure fitness of use for the four broad categories of water use that are recognised in the National Water Act (No. 36 of 1998):
  • domestic purposes
  • industrial purposes
  • agricultural purposes
  • recreational purposes.
• The water quality requirements of these water uses and those for the protection of the health of aquatic ecosystems form the basis on which the overall fitness for use of water is judged.
• The DWA has published a set of water quality guidelines → give the acceptable levels of impurities for different uses, including crop irrigation and livestock watering.

Important definitions:

• Water supply: how much water you have.
• Water source: where the available water is stored (surface or underground).

3.2 Sources of water for agriculture

• All water used for agriculture comes from rain. Rain forms part of the water cycle.
• When it rains, one of a number of things can happen. It can fall:
  • on the soil, and then remain in the top layer of the soil (soil water)
  • on the soil and then enter the soil (subsoil or groundwater)
  • in the sea, lake, dam or river (surface water).

3.2.1 Soil water

• Soil water = water or moisture found in the top layer of soil.
• Some soil types hold water better than others:
  • sandy soils = permeable → don’t hold water very well → water drains easily
  • clay soils = not very permeable → holds water very well → water doesn’t drain easily.

3.2.2 Groundwater

• Groundwater = water that enters the soil and moves down through the soil until it reaches rock.
  • The water collects above the rock and in cracks in the rock.
• Groundwater is available in different ways:
  • Where the layer of rock meets the side of a hill, the groundwater comes out of the ground in the form of a spring.
  • Where there is a shallow layer of soil above the rock, the groundwater may rise up to the surface and form a vlei. Vleis usually occur in low-lying places and may only have surface water during the rainy season.
  • People dig wells or boreholes to reach the groundwater. Boreholes are usually deeper than wells and supply more water. This is because boreholes often reach deep groundwater that is trapped below a layer of rock.

3.2.3 Surface water

Related Items

• Surface water = water on the surface of the earth.
• When it rains, the runoff water that moves along the top of the soil goes into streams → the streams join with rivers → the rivers may join into a larger river that flows on to the sea or to a lake.
• People sometimes build dams along streams and rivers to store some of the water.
• Not all surface water can be used for agriculture (e.g. seawater needs to be desalinated).

3.3. Ways in which water is used for agriculture
3.3.1 Water uses for livestock farming

• For drinking purposes for their livestock:
  • take animals to a river or stream in morning or evening
  • collect water in a water tank and flow the water to water troughs
  • use a windmill to pump water from a well or borehole → store the water in a water tank and flow into drinking troughs.
• Other purposes:
  • to dip their animals
  • to clean animal pens, milking sheds, etc.
  • to irrigate artificial pastures (e.g. alfalfa).

3.3.2 Water used for crop farming

• Water used to water (irrigate) crops.
• Water management done by:
  • choosing crops according to rainfall (e.g. planting drought-tolerant crops: sorghum instead of maize)
  • growing crops that have a short growing season (e.g. sunflower)
  • conserving rainwater in the soil
  • using suitable irrigation → has advantages –
  • increases the chances of a good harvest
  • enables crops in low rainfall areas that could not normally grow there
  • enables farmers to grow plants during the dry season.

Conserving rainwater in the soil
Rainwater can:

• run off along the surface of the ground → does not reach plant roots
• evaporate
• enter the soil.

So, to conserve water:

• reduce evaporation by mulching
• increase the amount of rainwater that enters the soil:
  • Method 1: stop soil erosion.
  • Method 2: pocketing water → make shallow pockets in the soil.
  • Method 3: end-of-season ploughing → at the end of the rainy season the soil is still moist → when the next rainy season starts, the soil is loose.
  • Method 4: no-tillage farming → crop remains to form mulch → prevents evaporation and soil doesn’t become compacted
  • Method 5: preserving the plant cover → decreases water runoff → prevents soil compaction.

Quality of irrigation water

Water laboratories test water to ensure suitable quality.

3.4 Factors affecting water supply in agriculture
Water supply is influenced by rainfall. The rainfall of an area has three important aspects:

• average annual rainfall
• seasonal distribution
• intensity.

3.4.1 Average annual rainfall

• Rainfall in SA is extremely variable: it ranges from droughts to flooding.
• Only one third of SA receives more than 600 mm of rain, the minimum for successful crop production.
• The remaining two-thirds of the country is used for livestock grazing natural vegetation.

3.4.2 Seasonal distribution
The season in which it rains determines the crops:

• crops that grow well in cooler temperatures will grow better in winter rainfall areas
• crops that grow well in warm or hot temperatures will grow better in summer rainfall areas than winter rainfall areas
• winter cereals ( wheat, barley, oats) are grown in winter in the winter rainfall areas or under irrigation in the summer rainfall areas.

3.4.3 Intensity
Most of South Africa faces a shortage of water. Even in the higher rainfall areas on the eastern side of the country, periods or seasons of drought can occur.

• In most summer rainfall areas, thundershowers occur: short and intense rainfall → results in the flooding of rivers and low-lying areas → flooding can wash away crops and the fertile layer of topsoil.
• If the intensity is too low, especially when temperatures are high, the rainfall may evaporate.
• In the winter rainfall areas, the rain usually falls in long periods of soft rain.

To avoid crop failure, farmers need to manage water well.

3.5 Basic agricultural practices that contribute to water pollution

• Agriculture uses 70% of the Earth’s surface water supplies.
• The largest part of agricultural water is recycled back to surface and groundwater, the rest is lost through evaporation.
• Agriculture contributes to water pollution through:
  • ploughing
  • irrigation
  • fertilising
  • manure spreading
  • using pesticides
  • cleaning feedlots, pens and milking stables.

3.5.1 Ploughing

• Loose soil is washed away by rain or carried away by wind.
• Soil can be carried into surface water and cause siltation of dams and riverbeds.
• Pesticides or phosphorus from fertiliser stick to soil particles and can get into surface water.

3.5.2 Irrigation
Irrigation can pollute ground and surface water sources through runoff of salts, pesticides and fertiliser.

3.5.3 Fertilising

• Run-off of nitrates and phosphorus causes eutrophication → fish die and water tastes unpleasant.
• Nitrates leach into groundwater sources. Nitrates in surface and groundwater are a threat to public health. Soluble fertilisers contain nitrates and water with high levels of nitrate, which
  • encourages the growth of algae and bacteria that use up the oxygen in the water → fish and other water animals can’t survive.
  • makes the water unsafe for human and animal consumption.
  • contaminates edible fish → causes health problems in humans.
• Fertiliser and pesticides contain high levels of trace elements e.g. selenium → causes ecological damage and health problems if it gets into surface water sources.

3.5.4 Pesticides

• Pesticides kill pests but they also kill other living creatures.
• Pesticides can run off into surface water and:
  • damage its ecosystem
  • cause growth problems and infertility in animals → can upset the delicate balance between predators and prey in the ecosystem
  • cause illness in people who eat contaminated fish
  • get carried over long distances by the wind → pollutes water sources thousands of kilometres away
  • leach into groundwater → contaminates wells → causes illness in humans.

3.5.5 Manure spreading
Too much manure can pollute ground and surface water with:

• nitrogen
• phosphorus
• pathogens.

3.5.6 Cleaning of feedlots, pens and milking stables
Feedlots, pens and milking stables must be cleaned, but:

• the wastewater can get into surface water sources → contaminates it with urine, faeces and pathogens
• if contaminated water is used to irrigate crops → the crops can become contaminated
• nitrogen and metals in the urine can leach into the groundwater → contaminates the groundwater.

3.6 How to prevent water pollution
3.6.1 Practices that farmers can implement

• Irrigate crops in a precise and planned way:
  • take care that the water lands on the crops only
  • don’t let irrigation systems run unsupervised or for lengthy periods to:
    • prevent soil from becoming waterlogged
    • reduce water runoff
    • use less water.
• Test the soil to avoid over-fertilising.
• Keep the soil covered with vegetation to prevent the build-up of soluble nitrogen, which can run off into surface water or leach into groundwater.
• Implement soil erosion control measures.
• Manage the period between crops. Plant green manure crops between harvesting and planting again. Do not plough plant material left over from harvesting (for example straw or roots) into the soil too soon.
• Do not apply too much manure to the soil.
• Apply pesticides properly:
  • do not apply too much
  • only apply it in suitable weather conditions (not in windy or rainy weather)
  • limit aerial spraying
  • only use pesticides for what they are intended
  • dispose of empty pesticide containers in the correct way
  • don’t flush out pesticide containers in rivers or other reservoirs.

3.6.2 Legislation to prevent water pollution
National Water Act (Act No. 36 of 1998)
The Act states that:

• The Minister of Water Affairs is the public trustee of the nation’s water resources (surface and groundwater). The Minister must ensure that these resources are protected, used, developed, conserved, managed and controlled in a sustainable and equitable manner.
• Persons who wish to use water, e.g. farmers, have to apply to the Department of Water Affairs to register that use. Water uses that involve farming operations include:
  • abstraction of water from a water resource (pumping water from a river)
  • storing of water
  • impeding or diverting the flow of water in a watercourse
  • irrigating land with waste water
  • discharging waste into a water resource
  • disposing of waste in a manner which may detrimentally impact on a water resource
  • altering the bed, banks, course or characteristics of a watercourse
  • removing and disposing of water found underground.
• Water may be used without authorisation for reasonable domestic use, domestic gardening, animal watering (not feedlots), fire fighting and certain recreational purposes.

Sustainable Utilisation and Protection of Agricultural Resources (SUPAR) Bill
The Bill seeks to:

• maximise productivity and sustainable utilisation of natural agricultural resources
• provide for the control of weeds or invader plants
• provide for the subdivision and change of utilisation of agricultural land.

The Bill will replace the Conservation of Agricultural Resources Act, No. 43 of 1993 (CARA) and the subdivision of Agricultural Land Act, No. 70 of 1970.

Unit 4: Agricultural Pollution

4.1 Agricultural pollution

• To pollute = to put harmful substances (dirt, oil, chemicals, germs) into the air, water or soil.
• These harmful substances are called pollutants or contaminants → can cause harm to the environment, people and animals.
• Agricultural pollution is the pollution of water, soil or air by agricultural activities → affects agriculture because farmers use the water, soil or air again.
• Three factors determine the severity of a pollutant:
  • its chemical nature (whether it is a salt, heavy metal, acid, etc.)
  • its concentration (the higher the concentration, the more harmful it is)
  • its persistence (the longer it stays in the air, water or soil before it is broken down, the more harmful it is).

4.2 Types of pollution
Types of pollution are summarised in the mindmap below.

Agricultural pollution

4.3 Major kinds of soil pollutants
4.3.1 Fertiliser

• Chemical fertiliser can pollute the soil and water:
  • too much fertiliser used → soil is polluted. (Different crops need different types and amounts of minerals. Test the soil to determine amount required.)
  • Fertiliser nutrients are soluble: rain causes runoff → can contaminate water sources.
• To control soil pollution:
  • proper application methods and doses
  • reduce the use of chemical fertiliser by crop rotation or organic compost.

4.3.2 Herbicides and pesticides

• If not biodegradable → they stay in the soil → continue killing plants and animals.
• The harmful substances can build up in ecosystems, e.g. DDT → becomes more concentrated as it moves up the food chain.
• Best to use biological methods (natural enemies) of pest control.

4.3.3 Wrong irrigation practices

• Irrigation can increase the salination and acidification of soil. If the soil is not properly drained, salination and acidification will increase.
• If soil is irrigated with treated wastewater, it can cause pollution with heavy metals,
  e.g. cadmium (Cd). (Heavy metals are metals with densities of more than 5,0 Mg m3. Low concentrations are not toxic, or could even be beneficial. Higher concentrations are toxic.)

4.3.4 Improper soil management

• Farm soil should be protected against erosion and proper draining systems should be created to maintain the soil.
• If soil is not protected, the structure of the soil can change → become less suitable for the crops.

4.3.5 Spillages
Use proper waste management to get rid of harmful substances, e.g. diesel.

4.4 The economic impact of soil pollutants
Soil pollution decreases the quality of soil and water. Economic consequences include:

• Increased soil salinity due to:
  • poor irrigation practices, poor fertilising practices and low drainage → soil becomes unsuitable for agricultural purposes → fewer crops are produced → food becomes more expensive. (If soil is badly degraded, farmers must find alternative land to farm.)
• Loss of fertility:
  • because farmers apply fertilisers without testing the soil first, the balance between nutrients in the soil becomes upset → this changes the soil structure, disturbs the chemical balance of the soil and kills the natural organisms → lower crop production → food becomes more expensive. (If soil loses too much fertility, farmers must find alternative land to farm. Also, plant cover is damaged, which leads to erosion.)
• Crops that grow in polluted soil will contain harmful contaminants.
• Soil pollution causes water pollution, due to runoff into surface water sources and leaching into groundwater sources. Alternative water sources have to be found = very expensive.

4.5 Waste management in agriculture

• Waste management in agriculture deals with the waste produced by farming activities, e.g. wasted feed, animal bedding and runoff from feedlots and holding areas.
• If this waste is not managed properly → water sources are polluted.
• Adding manure to the soil saves money → it increases the organic content of the farmland and saves the cost of fertiliser.

4.5.1 Farm Waste Management Plan

• Farm Waste Management Plan (FWMP) determines where the waste is produced, what it can be used for, and where it should be stored.
• FWMP must have a map to indicate:
  • pastures where animals graze (if rotational grazing is practised, note for how long the animals remain in one pasture)
  • fields where crops are grown (if crop rotation is practised, note when the field is planted and with what)
  • water sources, such as rivers, wells, etc.
  • areas of risk e.g. a slope near a river.
• The FWMP should address:
  • what type of waste is produced, and how much of each type of waste
  • when is the waste produced (continuously, or only periodically)
  • how much land is available for spreading
  • how much storage space is available.

4.5.2 Manure

• Can be stored:
  • in piles on the field where it will be spread
  • in tanks below or on the ground.
• Should only be applied in suitable weather conditions (no rain and no snow).
• Do not spread near water sources. Divert runoff from areas above the fields where it will be spread.
  • Use soil management practices to prevent runoff.
• Regularly check storage tank for leaks.
• If there are many animals → install a digester → generates biogas for electricity.

4.5.3 Silage

• Silage = feeding material (fodder) made from grass crops (e.g. maize, sorghum or alfalfa).
  • The plant material is first allowed to ferment and stored for use when grazing is scarce.
• The process of making silage is called silaging or ensiling.
• Two methods are used:
  • put plant material in a silo = a strong plastic container, plastic bag or tower, or a trench or pit in the ground that is lined with clay or cement and covered with a large plastic sheet
  • first bale the plant material, and then wrap the bales in plastic.
• During fermentation a liquid is formed → contains nitric acid → can pollute water sources and cause eutrophication.
  • To minimise the amount of liquid that is formed → make sure that water cannot reach the plant material.
  • To prevent pollution of water sources → do not make the silo closer than 10 metres from a water source.

Topic 3: Questions

• Answer the questions below.
• Give yourself one hour.
• Check your answers afterwards and do corrections.

Questions

1. Describe the pressure a growing population places on natural resources. (5)
2. Outline three agricultural practices that can contribute to the sustainable utilisation of natural resources in agriculture. (6)
3. Describe the three types of soil degradation. (6)
4. Name five warning signs that soil erosion is taking place. (5)
5. Define water quality. (6)
6. What is meant by water source? (1)
7. Describe the water cycle. (10)
8. Describe five methods that farmers can use to increase the amount of water that enters the soil. (10)
9. What is agricultural pollution? (4)
10. List the five major soil pollutants. (5)
11. Describe the three factors that determine the severity of a pollutant. (6)
12. What is silage and how does it contribute to pollution? (6)

[Total marks 70]