Miscanthus Sinensis is as Efficient as Miscanthus × Giganteus for Nitrogen Recycling in spite of Smaller Nitrogen Fluxes
Leroy, J. | Ferchaud, F. | Giauffret, C. | B., Mary | Fingar, L. | Mignot, E. | Arnoult, S. | Lenoir, S. | Martin, D. | Brancourt-Hulmel, M. | Zapater, M.
Nitrogen (N) recycling is a key mechanism to ensure the sustainability of miscanthus production with no or small fertiliser inputs, but little is known on the subject in miscanthus species other than the most cultivated Miscanthus × giganteus. This field experiment on Miscanthus × giganteus and Miscanthus sinensis quantified plant biomass and N stock dynamics during two years. Endogenous net N fluxes, calculated from the evolution of plant N content throughout time, were higher in Miscanthus × giganteus than in Miscanthus sinensis. Indeed, 79 kg N ha⁻¹ and 105 to 197 kg N ha⁻¹ were remobilised during spring and autumn, respectively, for Miscanthus × giganteus, as opposed to 13 to 25 kg N ha⁻¹ and 46 to 128 kg N ha⁻¹ for Miscanthus sinensis. However, N recycling efficiency, defined as the ratio between N remobilisation fluxes and the maximum above-ground N content, did not differ significantly between the two species. N recycling efficiency ranged from 8 to 27% for spring remobilisation and from 63 to 74% and 24 to 38% for autumn remobilisation calculated on above-ground and below-ground N, respectively. Exogenous N, the main source of N to constitute maximum plant N content for all genotypes, was provided by fertilisation (22 to 24%) and organic matter mineralisation or other sources (43 to 59%). During winter, 42 to 56% of plant N content was lost. Only a small part of these plant N losses was due to abscised leaves (6–12% of the maximum plant N content). Our results show that Miscanthus sinensis is as efficient as Miscanthus × giganteus in N recycling and N use efficiency and as performant as other perennial species.
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