Crop plants Flashcards
How can crop yields be increased?
Polythene tunnels
Glasshouses
Fertilisers
Pest control
What are polythene tunnels?
Big tube-like structures made from polythene
How do polythene tunnels protect the crops?
They protect crops from the effects of weather e.g. wind, rain and extreme temperatures
They are large enough for people and machines to work inside and can provide warmer conditions than if the crops were grown inside
How do glasshouses protect the crops?
Keeping plants enclosed makes it easier to keep them free from pests and diseases and protects them from the effects from the weather
Farmers often supply artificial light after the sun goes down to give their plants more time to photosynthesise
Glasshouses trap the Sun’s heat to keep the plants warm. In winter, a heater may also be used
Farmers can increase the level of CO2 in a greenhouse e.g. by using a paraffin heater for heating - as the paraffin burns, it makes CO2 as a by-product
How does increasing the CO2 concentration and temperature in a glasshouse increase crop yields?
By increasing the CO2 concentration and temperature, a farmer can increase the rate of photosynthesis for the plants. This means that plants will grow faster and bigger - and crop yields will be higher
How do fertilisers help increase plant yields?
Plants need certain elements e.g. nitrogen, phosphorous and potassium, so that they can make important compounds like proteins
If plants don’t get enough of these elements, their growth and life processes are affected
Sometimes these elements are missing from the soil because they’ve been used up by a previous crop
Farmers use fertilisers to replace these missing elements to provide more of them. This helps to increase crop yield.
What reasons are there for pest control?
Pests are controlled to prevent them from feeding on or damaging crops. This means that fewer plants are damaged or destroyed, increasing crop yield
What are pesticides and what are the advantages of them?
Pesticides are chemicals that farmers spray on their crops to kill pests.
They are very effective
What are the disadvantages of pesticides?
They are expensive Pests can become resistant to them They can cause environmental damage They can harm other (useful) wildlife e.g. pollinating insects They are poisonous
What is biological control?
An alternative to pest control, using other organisms to reduce the numbers of pests e.g. by encouraging wild organisms or adding new ones - these could be predators, parasites or disease-causing
What are the advantages of biological control?
Can be very effective
Less harmful to wildlife
Longer-lasting effect
What are disadvantages of biological control?
Never completely gets rid of a pest
Can cause other problems e.g. they can become a pest themselves
Harder to control
