ORGANIC CARBON STOCKS IN A SILTY TEXTURED SOIL FOLLOWING REINTEGRATION OF A 20 YEARS OLD MISCANTHUS × GIGANTEUS SITE INTO A CROP ROTATION

• Published in: Frontiers of Agricultural Science and Engineering Vol. 10; no. 2; pp. 183 - 197
• Main Authors: ESSICH, Lisa, RUSER, Reiner, HARTUNG, Jens, HANEMANN, Anne, GASSNER, Meike, OBERDORFER, Liam, BREUER, Jörn, RECKNAGEL, Jürgen, NUßBAUMER, Helmut, MÜLLER, Torsten
• Format: Journal Article
• Language: English
• Published: Higher Education Press 2023
• Subjects: biobased energy crops; biobased energy crops|c balance|humus accumulation; C balance; humus accumulation
• ISSN: 2095-7505; 2095-977X
• DOI: 10.15302/J-FASE-2023485

● 0.98 Mg·ha −1·yr −1 C org accumulation under miscanthus over 26 years. ● C org accumulation under miscanthus continued even up to 26 years. ● Reintegration of a miscanthus site into a crop rotation induced decreasing C stocks at first after 6 years. Miscanthus × giganteus may play an important role in replacing fossil energy resources by bio-based alternatives. One further advantage of miscanthus production is the generally high soil organic carbon (C org) enrichment in soils. Due to declining yields, miscanthus stocks are commonly reintegrated into crop rotation after approximately 20 years. Currently there is only few information, whether these high amounts of C org can be conserved while intensifying soil tillage and crop management after reintegration. Therefore, we monitored C org stocks in a control with more than 20 years of continuous miscanthus and in a treatment with reintegration of a 20-years old miscanthus stock into an organic crop rotation. Based on δ 13C soil values, we calculated an annual C org enrichment of 0.98 Mg·ha −1·yr −1 C under miscanthus. More than 95% of the miscanthus-C was determined in the upper 0.25 m of soil. Continuing miscanthus cultivation did not affect yields during the first five extension years and C org stocks increased further. Following reintegration, C org stocks remained constant during five years, which was mainly attributed to the humification and/or stabilization of high amounts of destroyed roots and rhizomes. A significant decrease in C org (−5.7 Mg·ha −1 C) compared to the continuing miscanthus cultivation was at first measured six years after reintegration into crop rotation, underlining the need of long-term investigations. Our data also show, that miscanthus production cycles can be extended in our region, and that sowing of the alfalfa grass mixture after rhizome/root destruction was efficient in preserving C org stocks for at least first five years after reintegration.