Agriculture

Except Abiotic and Biotic Factors

Name the 2 ways to manipulate food species to increase productivity:

• Increasing the stocking/crop density

• Monocultures

What is stocking/crop density?

Stocking density refers to the number of animals per unit of land.

Crop density refers to the number of plants grown per unit of land.

Advantages of increased density

• Efficient land use

• Easier management (controlled feeding, irrigation, harvesting)

• Maximises productivity

Disadvantages of increased density

• Overcrowding can lead to resource competition and disease spread.

• Soil degradation (overplanting)

What are monocultures?

The cultivation of a single crop in a given area.

Advantages of Monocultures

• Efficient (easier to manage, harvest)

• Consistent quality (all crops grown under same conditions)

Disadvantages of Monocultures

• Soil degradation

• Loss of biodiversity

• Dependency on fertilisers and pesticides

• Pest and disease vulnerability

Definition of Genetic Manipulation

Manipulation of an organism's genes using biotechnology

What are the 3 examples of genetic manipulation?

1. Selective breeding

2. Asexual reproduction

3. Genetic engineering / Transgenics / Genetic Modification

What is selective breeding?

The selection of plants or animals with the desired characteristic by the farmer/breeder and are bred together so that the offspring have the desired trait.

What’s the disadvantage of selective breeding?

There’s an increased risk of inbreeding

Examples of Selectively Bred Animals

• Highland Cow - Even temper, few stress problems

• Large white - Good quality bacon

• Merino - Good quality wool

How do plants reproduce asexually?

Via vegetative propagation

Advantages of Plants Asexual Reproduction

• Uniform phenotype

Disadvantages of Plants Asexual Reproduction

• No genetic variation

• Uniform disease susceptibility

• Fewer offspring produced

How do animals reproduce asexually?

Via cloning

Outline the Method of SCNT

1. The animal to be cloned donates a somatic body cell

2. The nucleus from the somatic cell is removed

3. An unfertilised egg cell is extracted from the female egg donor

4. The unfertilised egg cell is enucleated

5. The nucleus from the somatic body cell is fused with the enucleated egg cell using an electric current

6. The hybrid zygote cell is now treated to encourage it to divide by mitosis

7. The embryo is implanted into the surrogate mother for gestation and birth

What are the potential applications of artificial asexual reproduction?

• Valuable animals that die can be replaced with genetically identical animals

• Herds culled due to a disease outbreak can be replaced with genetically identical animals

• Large numbers of animals with desirable characteristics can be produced

Definition of Genetic Engineering

The direct manipulation of an organism's DNA to change its traits.

Definition of Transgenics

The transfer of DNA from one species to another

Examples of GM crops:

• GM rice varieties

• Bt crops

What are Bt crops?

Soya is genetically modified to produce Bt proteins.

Bt proteins are toxic to many pests and resistant to weed killer.

This means farmers don’t need to spray insecticides, and can spray weed killer to get rid of weeds and don’t kill the soya.

What are the disadvantages of Bt crops?

• Pollinators and predators may be damaged by the toxins from the Bt protein

• Insects might become resistant to the toxic Bt protein

• Genes might spread to wild populations, creating "superweeds"

• Reduces biodiversity

• Claims that GM foods can increase food allergies

Why are GM crops costly for farmers, especially in LEDCs?

IP rights and patents for specific GM crops are owned by specific companies that control the prices and availability of the seed.

GM seeds need to be purchased each year, rather than harvesting seeds from an existing crops.

Name the 5 ways in which agricultural energetics can be quantified:

1. Productivity

2. Efficiency

3. Intensive/Extensive systems

4. Energy Subsidies

5. Energy ratios

What is productivity?

Measures the amount of output per unit of input

What is efficiency?

Measures how effectively energy is converted into useful agricultural output. It focuses on the energy ratio (output vs. input).

What is intensive agriculture?

Agriculture that involves increasing the amount of artificial inputs (like fertilisers, pesticides) to increase and maximise agricultural yield per unit of land.

What is extensive agriculture?

Agriculture whereby agricultural effort is spread over a larger land area

There is lower productivity per unit of land area, but overall global productivity is higher due to more areas being farmed.

Lower input farming techniques are used.

Explain the Law of Diminishing Returns.

At a certain point, any further increase in inputs is inefficient, because outputs will not increase by an equivalent amount.

Beyond the certain point, increasing inputs leads to smaller increases in production, and efficiency declines

What are energy subsidies and can you give some examples?

Any input that aids productivity, but requires the use of energy to do so.

Examples include:

• Machinery - Fuel is needed for machinery for ploughing

• Fertilisers - Manufacture of nitrate fertilisers

• Pesticides - Manufacture of pesticides

• Transport - Transporting food to customers

• Processing - Heat for drying harvested grain

Why does intensive agriculture have higher energy inputs? What’s the energy used in?

Energy is used in:

• fertiliser manufacture

• fuel for ploughing

• pumped irrigation

• the artificial control of temperatures

• artificial lighting

What are energy ratios?

These compare energy inputs and outputs.

It is the number of units of food energy produced per unit of energy input.

Energy Ratio Calculation

Energy Output / Energy Input

Suggest 2 reasons why poultry farming has a higher energy input than beef farming?

• Energy is used for artificial lighting

• Energy is used for heating

• Energy is used for machinery

• Material is used for the coop

• Production/growth of chicken feed

The higher the energy ratio...

...the more efficient food production (more food energy for less input)

What are Food Conversion Ratios?

A measure of the efficiency with which an organism converts its food into its own increasing biomass.

(the mass of food needed to produce one unit of new tissue)

The lower the food conversion ratio...

...the better the conversion of food into animal biomass.

Outline the 3 main environmental impacts of agriculture:

1. Impacts on habitats

2. Increased pollution

3. Changes to the hydrological cycle

Name the 6 impacts agriculture has on habitats:

• Habitat clearance

• Wetland drainage

• Ploughing of grassland

• Reduced biodiversity

• Genetic contamination

• Soil degradation and erosion

Why does habitat clearance take place and why is it bad?

• Large areas of land are cleared to produce farmland

• This is done in areas where climate is favourable and soils are fertile, like where the natural biomes are (forests or grasslands)

Why does wetland drainage take place and why is it bad?

Farmland is drained to produce more aerobic soils.

Wetland species and the supported ecosystem may not be able to survive the changes

Why is ploughing grassland bad?

• Removes native plant cover and disrupts food chains

• Exposes topsoil to wind and water, leading to loss of nutrients

• Loss of grassland species due to them losing their habitat

How do agroecosystems reduce biodiversity?

Agroecosystems replace the diverse communities of indigenous species with a community of fewer species, many of which may not be indigenous.

The indigenous species will not be able to survive the new conditions, or may be removed as they are prey to new competitors

What is genetic contamination and why is it bad?

The unintended spread of genes from GM crops to wild relatives or traditional crop varieties.

It can lead to wild plants getting the gene for herbicide resistance, making them harder to control

What does soil degradation and erosion lead to?

• Fertile land turns into desert, reducing biodiversity.

• Eroded soil washes into rivers, causing siltation and harming fish.

• Less fertile soil means lower yields, requiring more fertilisers.

Name the 3 ways agriculture leads to pollution:

1. Pesticide Usage

2. Nutrient Leaching

3. Emissions of Greenhouse gases

How do pesticides pollute?

They leach into water bodies, killing non target species

How do inorganic and organic nutrients pollute?

• Leached inorganic nutrients cause eutrophication

• Leached organic nutrients cause deoxygenation and pathogen spread

Example of Nutrient Pollution:

Nitrates can be leached from farmland into water bodies that are used as sources of potable water for human consumption.

High nitrate levels can cause blue baby syndrome (methaemoglobinemia) and nitrates may be a human carcinogen

How is methane released by agriculture?

• Microbial anaerobic digestion
  

• Livestock intestines
  

• Rice padi fields

How is CO₂ released by agriculture?

• Fossil fuel use
  

• Ploughing increases soil aerobic respiration

How Is NO_x released by agriculture?

• Livestock manure
  

• Nitrogen fertilisers

What are the 2 changes to the hydrological cycle that agriculture cause?

1. Depleted aquifers
   

2. Changes in evapotranspiration.

How does agriculture lead to depleted aquifers?

Through unsustainable irrigation

How does agriculture lead to changes in evapotranspiration?

Changes depend on the ecosystem present before farming began.

• Evapotranspiration is increased in arid areas

• Evapotranspiration is reduced in areas where forests were removed

Name the 3 economic influences on agriculture:

1. Subsidies

2. Guaranteed Prices

3. Quotas

What are subsidies?

Governments pay farmers to limit yields or diversify

How did subsidies come about and what do they do?

• Post WW2, farmers in Europe could not afford to invest in more productive methods because they were unsure they would earn enough to repay their loans taken out

• To solve this, grants were made available so farmers could get financial assistance for a wide range of projects to increase food production

What were the grants/subsidies used for?

- Hedgerow removal (to increase field size)

- Use of machinery

- Drainage of wetlands

- Beetle banks (to increase habitat)

- Organic farming (reduced pesticides, so reduced nutrient leaching)

- Skylark plots

What are guaranteed prices?

Government set the price of a product

Why were guaranteed prices introduced?

Increasing production meant that if output exceeded demand, then the market price would drop, and the farmers could make a loss, despite the high yield. Therefore, to solve this issue, a guaranteed market provides a price support system.

• Creates financial stability for farmers and consumers

• Food production was raised

If there was a surplus harvest, how did guaranteed pricing work?

The government would buy some of the harvest from the farmers to create an artificial market shortage and raise the price to an agreed level that had been set earlier in the year

If there was a poor harvest, how did guaranteed pricing work?

To prevent raised prices, the government would sell the surplus food from previous years (milk powder, grain, cheese) to bring the market price down to the agreed level

What are quotas?

Farmers are given limits on what they are allowed to produce

(For example, dairy farmers are given a limit on the amount of milk they can sell)

Why were quotas introduced?

• By the 1970s, food production had increased to the level where there were more surpluses than shortages in MEDCs
  

• Surplus food in one country couldn't be sold to other MEDCs, because they also produced surpluses
  

• Countries of Eastern Europe and the USSR needed food but could not afford to pay the full price

• Selling the surplus food in LEDCs would undercut local producers, put them out of business, and reduce long term food production

• Therefore, quotas prevents the overproduction of food

Political influences also include subsidies, guaranteed prices, and quotas. Name the 2 other political influences on agriculture:

1. Trade controls

2. Economic controls

What are trade controls?

Government put tariffs on the trading of particular products

What do trade controls do?

• Protects local farmers from cheaper foreign imports
  

• Ensures food security by controlling exports
  

• During the war, Europe could not produce enough food to feed everyone. Without a major change in food availability, there would have been serious food shortages, possibly famine. Food aid from the USA helped reduce these issues.

What are economic controls?

Government policies that regulate the agricultural market to maintain stable prices and production.

Outline 3 reasons why economic controls good

• Prevents price volatility that harms farmers and consumers

• Controls food inflation

• Ensures affordable food supply

Issue: Decreasing nutrient supply

Current supplies of rock phosphates to produce phosphate fertilisers are non renewable.

What are the 2 ways to reduce the issue of decreasing nutrient supplies?

1. Use natural processes

2. Increase the natural nutrient supply

How to use natural processes to increase nutrient supply:

• Nitrogen-fixing bacteria. These bacteria naturally convert nitrogen from the air into a form plants can use.

• Decomposition. The breakdown of dead organic matter naturally releases nutrients back into the soil.

• Crop rotation. Planting different crops in a cycle helps maintain soil nutrients back into the soil.

What are 5 ways to increase increase natural nutrient supply?

• Recycling of organic matter - Using plant and animal waste to return nutrients to the soil

• Crop rotation

• Permaculture - A farming system that mimic natural ecosystem to maintain soil health and nutrient cycling

• Growth of legumes

• Conservation of soil biota

Issue: High amounts of Energy inputs

The manufacture of nitrate fertilisers requires large energy inputs from fossil fuels

What are the 2 sustainability strategies to minimise energy inputs?

• Using natural processes instead of artificial fertilisers

• Low tillage techniques

Issue: Decreasing Water Supplies

There is an overexploitation of rivers and groundwater reserves.

Soil salination is also caused by using saline irrigation water.

What are the sustainability strategies to conserve water supplies?

• Cultivating low water use crops
  

• Maintaining soil and soil organic matter
  

• Use of reservoirs and aquifer recharge
  

• Drip irrigation rather than overhead sprays

Issue: Atmospheric Pollution

• Atmospheric CO₂ levels increased
  

• Increased methane production in agriculture

How to reduce the atmospheric pollution from agriculture?

• Low tillage farming to reduce the decomposition of soil organic matter
  

• Reduced use of machinery
  

• Retain natural and semi natural ecosystems such as hedgerows, ditches, ponds, woodlands

How to make cattle produce less methane?

Feed them a high carb diet and grind their food first

Issue: Pesticide Usage

A reliance on chemical pesticides may be unsustainable.

The use of some pesticides has been banned or restricted due to their impacts on non-target species

Many pests have developed resistance to pesticides

What are 3 sustainable strategies to control pests?

1. Cultural pest control

2. Integrated control

3. Reduced use of antibiotics

Name the cultural pest control techniques

• Weeding

• Mulching

• Crop rotation

• Barrier crops

• Biological control

• Predator habitats

• Polyculture / companion crops.

What is integrated control?

An ecological approach to pest management, combining biological, cultural, and chemical control.

Name some integrated control techniques:

• Cultural pest control

• Growing pest resistant species

Why is the overuse of antibiotics bad?

Exposure to a high dose of an antibiotic may kill all of a pathogen population

 

• However, exposure to a lower dose of antibiotics may kill only the most sensitive individuals, so the surviving population will be less easily controlled by the antibiotic

• Also, increases in antibiotic resistant bacteria is an issue. Antibiotic resistant bacteria may be zoonoses, which cause disease if transferred to humans (E.coli)

Therefore, antibiotic use should be reduced.

What are the 4 factors influencing consumer choice?

• Social factors

• Cultural factors

• Religious factors

• Ethical factors

• Social factors

• Those with higher incomes may choose organic food, whilst others opt for budget friendly options

• Vegetarian/vegan diet

• Cultural factors

Horsemeat is not popular in the UK but is widely eaten in other European countries

• Religious factors

People with religious convictions may avoid certain foods

• Muslims do not eat pork

• Hindus do not eat beef

• Ethical factors. What are the 5 reasons?

A desire to reduce the environmental or social impact of food production can influence food choice.

• Local food / food miles

• Seasonal food

• Free range livestock

• Organic food

• Fairtrade

• Local food / food miles

Buying food that was produced nearby reduces the energy involved in transport and the pollution that would have been emitted

• Seasonal food

Choosing food that is grown when the local weather is suitable has a lower environmental impact than eating out of season food that needs heating, lighting, or transporting from another area with a suitable climate

• Free range livestock

Some consumers choose to buy eggs and meat from animals that are kept under conditions close to their natural conditions

The animals have the freedom to move around and search for food.

They often consider the conditions of intensive rearing to be cruel

• Organic food

Some consumers choose to buy food that was produced using natural processes wherever possible, rather than those using artificial processes for pest control and nutrient supply

• Fairtrade

Fairtrade food is produced in a way that provides an income for producers which means that they can afford basic human rights such as water, education, healthcare, and food