Quality and decomposition in soil of rhizome, root and senescent leaf from Miscanthus x giganteus, as affected by harvest date and N fertilization
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- Amougou, N., Bertrand, I., Machet, JM. et al. Plant Soil (2011) 338: 83. doi:10.1007/s11104-010-0443-x
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To predict the environmental benefits of energy crop production and use, the nature and fate of biomass residues in the soil need to be quantified. Our objective was to quantify Miscanthus x giganteus biomass recycling to soil and to assess how harvesting time and N fertilization affect their characteristics and subsequent biodegradability. The quantification of aerial and belowground biomass and their sampling were performed on 2- and 3-year-old Miscanthus stands, either fertilized with 120 kg N ha−1 year−1 or not fertilized, in autumn (maximal biomass production) and winter (maturity). Plant biomass was chemically characterized (total sugars, Klason lignin, C/N) and incubated in optimum decomposition conditions (15°C, −80 kPa) for 263 days, for C and N mineralization. Accumulation of carbon in rhizomes and roots was 7.5 to 10 t C ha−1 and represented about 50% of total plant biomass C. Senescent leaves represented about 1.5 t C ha−1 year−1. All residues, especially the roots, had high lignin contents, while the rhizomes also had a high soluble content due to their nutrient storage function. The C mineralization rates were closely related to the chemical characteristics of the residue, higher sugar and lower lignin contents leading to faster decomposition, as observed for rhizomes.