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| Titel |
Digestate and ash as alternatives to conventional fertilisers: Benefits and threats to soil biota |
| VerfasserIn |
Rachel Marshall, Alfonso J. Lag-Brotons, Ben Herbert, Lois Hurst, Nick Ostle, Ian C. Dodd, John Quinton, Ben Surridge, Farid Aiouache, Kirk T. Semple |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250153465
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| Publikation (Nr.) |
 EGU/EGU2017-18445.pdf |
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| Zusammenfassung |
| Recovering energy and nutrients from waste offers opportunities to tackle issues of energy
and food security whilst simultaneously improving waste management. Waste materials from
the bioenergy industry potentially contain valuable resources for use in agriculture and there
is growing evidence to suggest that the use of digestate, from anaerobic digestion, and
biomass ash from incineration processes could contribute to improving soil health and
nutrition.
The work presented here is part of the Adding Value to Ash and Digestate (AVAnD)
project which looks at the impacts of digestate and ash blends on soil fertility, crop yields and
soil health. Whilst increased crop productivity is one of the essential indicators of the success
of these alternative soil amendments; it is important that the impacts on soil biological
function is understood. Field and lab experiments were conducted with a number of different
fertiliser treatments, including conventional fertiliser (urea and superphosphate), digestate
from two contrasting feedstocks, ash material and ash-digestate blends. Looking across
different biological scales from soil microbe to soil macro-fauna, this work examines the
benefits and threats to soil biota arising from the use of ash-digestate fertilisers in
agriculture.
Measurements of microbial respiration and biomass (by chloroform fumigation) and
community composition (by phospholipid fatty acid analysis) were made at different
timescales (days/weeks). Data from these studies demonstrates that none of the soil
amendments decreased microbial activity or biomass in the short term (t= 1 month).
Additions of both conventional fertilisers and the fertilisers derived from waste stimulated
microbial activity with significantly higher respiration observed from the digestate based
treatments. Digestate-based treatments also resulted in higher soil microbial biomass and
differential effects were observed between digestate amendments with and without ash. These
results will be discussed in the context of microbial community change in response to the
amendments.
At the macro-fauna scale, effects of amendments on earthworm (Eisenia fetida and
Lumbricus terrestris) health were assessed using 14 day toxicity assays (4 application
rates between 85-340 kgN.ha−1) and with 48 hour avoidance tests. In general,
the addition of digestate-based fertilisers resulted in no observable toxic effects
and earthworms did not significantly avoid these materials when compared to a
conventional fertiliser. However, earthworms mortality was observed with one of
the ash-digestate blends applied at 340 kgN.ha−1, potentially linked to changes
in soil pH and elements speciation .It is therefore crucial that the effects of the
amendments on soil properties, and the implications this has for soil communities
at all scales, is understood to ensure sustainable soil management in agriculture. |
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