Inorganic fertilisers are necessary for high yields, but inputs need to be balanced to ensure supply does not exceed demand by more than 10%. Excessive nutrients encourage weeds, pests and diseases and cause water pollution. Fertilisers need to be applied only when they can be readily taken up by the crop otherwise the nutrients get lost to the environment causing pollution.
However, where possible, artificial fertilisers should be replaced with animal or green manures. This:
- Improves soil nutrient supply and soil structure
- Encourages the soil biota
- Keeps cost down
- Saves non-renewable resources
Poor use of fertilisers is the cause of a lot of environmental damage. Watercourses and hedgerows are particularly vulnerable. We have shown that fertiliser drift into hedgerows encourages weeds such as cleavers and barren brome, which can smother the other perennial flowers and grasses that support a lot of farmland wildlife.