An agrichemical is any substance used to help advance an agricultural ecosystem, or have an impact on the organisms that live on farms. Agrichemicals include the following main products:
- Pesticides (including: insecticides, herbicides, fungicides and nematicides)
- Soil conditioners
- Alkaline and acidifying agents
- Chemicals used to treat farm animals like antibiotics and hormones.
Agrichemicals have been widely used for many years to assist with the growth of crops and farm animals for food. However, many of these chemicals cause substantial environmental and ecological damage and in some instances the long term effects are still being determined. Many agrichemicals are toxic and can pose significant environmental and/or health risks, particularly in the event of accidental spills. In many countries, the use of agrichemicals is highly regulated.
Fertilisers are substances added to agricultural land to encourage plant growth and increase crop production. They can be chemically based (synthetic) or be made from living materials like animal manure or compost. Most fertilisers contain nitrogen, phosphorus and potassium (in varying amounts as required by the soil type). Globally it is estimated that about 138 million tonnes of fertilisers are used each year.
Pesticides are used to eradicate agricultural pests, any living thing that causes injury or disease to crops. Many different kinds of pesticides are used in agriculture, and they are generally categorised into groups according to the pest they are targeting:
Insecticides: are used to kill insects that eat crops or stored agricultural produce. Other pesticides target creatures like snails, slugs, rodents, and birds.
Herbicides: are used to kill weeds, or any unwanted plant that impedes the growth of crops.
Fungicides: are used to protect plants from fungal diseases.
Nematicides: are used to kill plant-parasitic nematodes (like roundworm or threadworm).
Very large quantities of pesticides are used globally. Approximately 2 to 3 billion kilograms of pesticides are used each year, at a total cost of about $20 billion US dollars.
Soil conditioners are products that are added to soil, usually to increase its ability to hold water and/or oxygen. Materials like peat, manure, sewage sludge, and shredded greenwaste are the most common.
Alkaline and acidifying agents
Plants that are grown in soil that is too alkaline or too acidic cannot obtain the necessary nutrients they need to grow. Soils that are too acidic are often treated with calcium – from limestone or crushed shells like mussel shells to reduce the acidity. Alkaline soils are much less common, but if they are present, sulphur or acidic organic matter can be added to assist.
Agrichemicals used to treat farm animals
A large number of agrichemicals can be given to farm animals. Antibiotics are used to control infectious diseases and parasites that often occur when animals are raised under extremely crowded conditions. Hormones are often given to animals to increase growth and productivity, such as the bovine growth hormone given to cows.