The impact of nitrogen fertilisers on field margin flora.

Abstract

This paper examines the potential role of misplaced nitrogen fertiliser as a causal factor in the degradation of field margin floras and encouragement of weed species. Evidence from the literature is reviewed and experimental evidence described. The weed species causing greatest concern in relation to field boundaries, Bromus sterilis, Galium aparine and Elymus repens, are all highly responsive to applied nitrogen. Experiments showed that B. sterilis is an effective competitor for nitrogen, but the response of G. aparine is inversely related to the competitive ability of competitor species. Application of nitrogen fertiliser to hedge bank vegetation did not alter botanical composition over a three year period, but increased vegetative and reproductive growth of transplanted B. sterilis. It is suggested that misplaced nitrogen fertiliser is more likely to affect the herbaceous composition of field boundaries where disturbance maintains a large number of safe sites for germination of annual plant seeds.