3.5 Impact of agriculture

Question 1

impacts of agricultural
practices

7

Answer 1

• overuse of insecticides and herbicides
• overuse of fertilisers
• mismanagement of irrigation causing salinisation and waterlogging
• overproduction and waste
• exhaustion of mineral ion content
• soil erosion
• cash crops replacing food crops

Question 2

overuse of insecticides and herbicides

Answer 2

1. Leads to resistance in pest population.
2. Can leads to environmental damage c.g. It can kill useful insect which aid in pollination like bees
3. There can be issue of spray drift where leaching can occur and the insecticide can be washed to a river and leads to dead of aquatic plants and animals.

Question 3

overuse of fertilisers

Answer 3

lakes and rivers bcomes unfavourable for aquatic life
lead to biomagnification
some fertiliser enters water sources / leaching;
due to surface run-off / heavy rainfall;
nitrates in water leads to eutrophication

Question 4

biomagnification

Answer 4

The increasing concentration of a toxic substance in the tissues of organisms at successively higher levels in a food chain

Question 5

process of eutrophication

Answer 5

The process of eutrophication initiates with the overuse of fertilizer.
The excess fertilizer runs off into the rivers and enters waterbodies such as lakes.
The fertilizers encourages the rapid growth of algae which is referred to as algae bloom.
This then results in the sunlight being blocked and reducing photosynthesis.
Which directly causes aqautic plants to die.
Bacteria then decomposes the dead plants which uses up oxygen present in the waterbody.
This leads to fishes and other organisms dying due to lack of oxygen.

Question 6

mismanagement of irrigation

Answer 6

• Damage to the soil structure; when air pockets are lost.
• Death of plant roots: waterlogged soil prevents roots getting sufficient oxygen to respire and cells start to die.
• leaching of nutrients: nutrients dissolve in water and as water drains away, nutrients are taken away.
• Soil erosion:water run off will take some of the soil particles with it.
• salinisation
• waterlogging

bold-> from ms

Question 7

the impact of waterlogged soil on crop production

Answer 7

reduces (oxygen concentration in) air spaces;
roots cannot respire;
roots cannot take up minerals / nutrients
kills (roots of) crops / drowns crops;
causing salinization and compacts soil;
reduces crop yields
soil is washed away;

Question 8

overproduction and waste

Answer 8

Waste of storage space
Waste of labour

Question 9

exhaustion of mineral ion content

Answer 9

The farmers use the soil over and over again with little to no rest which leaves the soil depleted of nutrients and minerals.
Solution: crop rotation, mixed cropping and leaving the land fallow.

Question 10

cash crops replacing food crops

Answer 10

crop grown, to be sold / for a profit
* ad-gain income to buy, seeds / tools / animals’
* dis- at risk of, crop failure if price of cash crop could drop

Question 11

Reasons why some regions uses more insecticides than others

6

Answer 11

• wealth / some regions cannot afford insecticides;
• lack of availability of insecticides in some regions;
• other biological controls used in some regions;
• greater use, on more valuable crops / where intensive production / value of agriculture to economy / more use if more crops;
• some regions naturally less affected by pests, due to climate / other environmental condition;
• lack of legislation;