Plant composition, herbage yield, and nitrogen objectives in Arrhenatherion grasslands affected by cattle slurry application

Cattle slurry is commonly used to fertilize grasslands, so its impact on plant composition and herbage properties is important. Cattle slurry at annual rates of 60 (S1), 120 (S2), 180 (S3), and 240 kg nitrogen (N)/ha (S4) was applied to Arrhenatherion grasslands in moderately wet (WS), slopy (SS), and moderately dry (DS) sites cut three times a year over six years, to assess its effects on plant functional types, the Ellenberg N indicator value (Ellenberg N), herbage dry matter (DM) yield, herbage N content and offtake, N nutrition index (NNI), and N use efficiency (NUE). The site-specific changes in an increase in graminoid cover, Ellenberg N, herbage DM yield and N offtake, and NNI along with slurry application rates revealed, while cover of legumes, short forbs, and NUE decreased. In more productive sites (WS and SS), slurry application in the amount of 180 kg N/ha could be suggested as a slurry dose ensuring beneficial agronomic objectives. However, nature conservation requirements via maintaining plant biodiversity were not met. On the contrary, short-term slurry application up to 120 kg N/ha ensured on permeable DS not only sufficient agronomic objectives, but also plant biodiversity conservation requirements.