Effect of inorganic fertilisers on botanical diversity and agriculture on the Somerset Levels (ENRR087)

This is the final report of the results from an eight year experiment carried out on Tadham/Tealham Moors in Somerset to establish whether there was a ‘safe’ amount of fertilizer nitrogen that could be applied to these meadows without reducing floristic diversity, also to establish the agricultural output achievable within any such safe fertilizer limit and the output foregone by adhering to this limit. From 1990 to 1993 the objectives of the project were extended to: establish the rate and degree of botanical ‘reversion’ and establish the impact on agricultural output when fertiliser N is withheld following years of input; also, to establish techniques to accelerate ‘reversion’ in botanical composition following botanical impoverishment by previous fertilizer use. This project has demonstrated that hay meadow communities of the Somerset Levels and Moors lose floristic diversity with inorganic fertilizer inputs. Once damaged by fertilizer use, they do not readily recover when inputs cease and the traditional management is resumed.