Food Production - Crop plants 17

Fertilisers

Farmers use fertilisers to put back into the nutrients that have been removed by growing corps.

Greenhouses

• Short wave radiation entering the greenhouse becomes longer radiation as it reflects off surfaces. This long wave radiation cannot escape, so the greenhouse heats up. A higher temperature can be more suitable for plant enzymes carrying out photosynthesis.

• Artificial lights can be used to maintain long hours of light availability even throughout winter months. The higher light intensity and longer light duration will result a higher rate of photosynthesis, increasing the yield.

• Green houses are able to control Carbon dioxide concentration. A higher carbon dioxide concentration provides more raw material for photosynthesis, increasing the rate of photosynthesis therefore resulting a higher production.

Pesticides

• Crop pests: organisms that harm crops by eating or damaging them, reducing crop yield.

• Pesticides: chemicals used to kill crop pests.

• different types of pesticides:

  • 1. Herbicides: to kill plants (grass)

  • 2. Insecticides: to kill insects

  • 3. Fungicides: to kill fungi

  • 4. Molluscicides: to kill snails and slugs.

• Problems using pesticides:

  • 1. The development of resistance

  • 2. Death of non-target (maybe useful) species

  • 3. Some persist in the soil and can be accumulated along food chains and harm useful animals (Bioaccumulation)

  • 4. some chemicals may remain on the surface of crops causing damage to people.

• e.g. DDT

Biological Control

It is the natural alternative to using chemical pesticides. Biological control uses a natural predator, herbivore, parasite or pathogen to reduce pest population.

e.g. ladybirds

Biological control has to be done carefully as the introduced predator can cause more harm than good