Effects of elevated CO2, N fertilization, and cutting regime on the production and quality of Lolium perenne L. shoot necromass

In the Swiss grassland FACE experiment, we measured the effect of elevated CO2 on the shoot necromass production and quality of Lolium perenne in 1995. Dead stubble of reproductive tillers and dead leaf sheaths were the main components of necromass. Elevated CO2 did not significantly change the amount and the nitrogen concentration of necromass. Significantly more necromass was produced and the N concentration was lower in the low N supply treatments. Total necromass amounted to 250–500 g m−2. Necromass N content was in the order of 5–6 g m−2. This underscores the importance of the carbon and nitrogen fluxes included in necromass and their importance for soil biology and fertility.