Ms Shirley Clerkin:

Because of its high level of phosphates, fertiliser, if it is spread too close to a hedge or if the run-off from it reaches a hedgerow, can affect the species diversity of a hedgerow. The floristic diversity of a hedge is one of its quality features. It can house a variety of flora. If it has too much nutrient input, you end up with a lot of nettle and dock and a few other species, so it results in a lower quality hedge because of a lower number of species. That is how fertiliser affects hedgerows.