Abstract
The C4 perennial grasses of the genus Erianthus have received considerable attention as novel energy crops because of their high yield potential and tolerance of environmental stresses. We conducted a field experiment in Nasushiobara city (36°55′N, 139°56′E), Japan. In order to clarify sources of nitrogen taken up by Erianthus, 15N-labelled ammonium sulphate was applied at 90 kgN/ha/yr to 1-year-old plants or to 2-year-old plants after transplanting in June 2009, and these platns received 90 kgN/ha/yr of unlabelled nitrogen in the years following or preceding labelled nitrogen applications. Total nitrogen contents were 76 kgN/ha in 1-year-old plants and 309 kgN/ha in 2-year-old plants. Percent fertilizer-N taken up by 1-year-old plants and 2-year-old plants were 28% and 60%, respectively. In 1-year-old plants, 33% of nitrogen taken up was derived from fertilizer and the remaining 67% from the soil. In 2-year-old plants, 20% of nitrogen taken up was derived from fertilizer, 15% from nitrogen stored in stubble during last winter and 65% from the soil. These results indicate the importance of the soil nitrogen and the stored nitrogen in stubble during winter of the previous year as nitrogen sources for Erianthus.
