Crop Yield

Rate of photosynthesis

• Directly affects crop yield

• Affected by the amount of light, carbon dioxide and temperature

  • These three factors need to be carefully controlled to maximise crop yield

  • Plants will grow bigger and faster, meaning crop yields will be higher

• Photosynthesis is for making food and helping the plant grow

Glasshouses: big greenhouses

Polytunnels: Big tube-like structures made from polythene

How to create ideal conditions for photosynthesis

• Enclosed plants in greenhouses keeps them mostly free from pests and diseases

• Also helps control the water supplied to crops

• Artificial light can be used after the Sun goes down to provided more photosynthesis time

• Glasshouses trap the Sun’s heat to keep plants warm, this can be achieved with a heater during winter

• Carbon dioxide level can be increased in glasshouses by using a parafin heater which burns parafin and makes carbon dioxide as a by-product

Fertilisers

• Plants require nitrogen, potassium and phosphorus to make important compounds like proteins

• When plants don’t have enough, their growth and life processes are affected

• These minerals may be missing in the soil if a previous crop existed there and used it up

• Farmers use fertilisers to replace these missing minerals or increase the amount of them in the soil

Pest control

• Pests: Microorganisms, insects and mammals that feed on crops

• They can be killed using various methods of pest controlled so less plants are damaged or destroyed

• Pesticides are chemical pest controls that are poisonous to humans and must be used carefully to keep the amount of pesticides in food below a safe level, them may also harm other wildlife

• Biological control is an alternative to pesticides, by using other organisms to reduce the numbers of pests, this can be done by encouraging wild organisms or adding new ones

  • Helpful organisms can be predators, parasites or disease-causing creatures

  • This has a longer-lasting effect than pesticides and is less harmful to wildlife

  • But introducing new organisms can cause problems as they may overpopulate or accidentally poison non-target species