Energizing marginal soils - The establishment of the energy crop Sida hermaphrodita as dependent on digestate fertilization, NPK, and legume intercropping

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Growing energy crops in marginal, nutrient-deficient soils is a more sustainable alternative to conventional cultivation. The use of energy-intensive synthetic fertilizers needs to be reduced, preferably via closed nutrient loops in the biomass production cycle. In the present study based on the first growing season of a mesocosm experiment using large bins outdoors, we evaluated the potential of the energy plant Sida hermaphrodita to grow in a marginal sandy soil. We applied different fertilization treatments using either digestate from biogas production or a commercial mineral NPK-fertilizer. To further increase independence from synthetically produced N-fertilizers, the legume plant Medicago sativa was intercropped to introduce atmospherically fixed nitrogen and potentially facilitate the production of additional S. hermaphrodita biomass. We found digestate to be the best performing fertilizer because it produced similar yields as the NPK fertilization but minimized nitrate leaching. Legume intercropping increased the total biomass yield by more than 100% compared to S. hermaphrodita single cropping in the fertilized variants. However, it negatively influenced the performance of S. hermaphrodita in the following year. We conclude that a successful establishment of S. hermaphrodita for biomass production in marginal soils is possible and digestate application formed the best fertilization method when considering a range of aspects including overall yield, nitrate leaching, nitrogen fixation of M. sativa, and sustainability over time.
Original languageEnglish
JournalBiomass and Bioenergy
Pages (from-to)9-16
Number of pages8
Publication statusPublished - 01.04.2016

Bibliographical note

This study was financed by Forschungszentrum Jülich, IBG 2 Plant Sciences core funding. The digestate and the sand was kindly provided by ADRW Naturpower GmbH & Co.Kg , Ameln, and Rheinische Baustoffwerke , Inden, respectively. We thank Freudenberger Feldsaaten GmbH , Krefeld for the inoculated M . sativa seeds. The kind provision of the dustbins by EGN mbH, Viersen, used as mesocosms for plant cultivation is highly appreciated. Many thanks to Lucy Harrison, Sabine Willbold and colleagues from ZEA-3 for the sampling and chemical analysis of the leachates, plant materials and soil samples. We thank Holger Wissel from IBG-3 for the δ 15 N analysis. We highly acknowledge the financial support of numerous students' apprentices by the DAAD and IAESTE program, providing great support for this experiment.