Biomass production and N balance of giant reed (Arundo donax L.) under high water and N input in Mediterranean environments

This study aimed to evaluate the productivity of Arundo donax under good water and N availability coming from non-conventional sources, in different Italian environments (Padova and Bologna in the north, Reggio Calabria and Catania in the south) in relation to three harvest periods (autumn; mid-winter; late-winter). In the northern locations A. donax had already reached maximum productivity the year after transplanting, with 85 and 98 t ha−1 of dry matter at Padova and Bologna, respectively. At Reggio Calabria and Catania a further biomass increase was obtained from the second to third year of cultivation, when production was 62 t ha−1 and 51 t ha−1, respectively. The average dry matter production was 74, 66 and 65 t ha−1 with autumn, mid-winter and late-winter harvesting, respectively. Under N input ranging from 225 to 329 kg ha−1 year−1 at the different locations, the apparent N balance (input–output) was negative except in Catania indicating a great potential of A. donax to provide high N uptake, which would be a useful feature in environments under the European Nitrates Directive.