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| Titel |
Biochar application to sandy and loamy soils for agricultural nutrient management |
| VerfasserIn |
Marco Gronwald, Axel Don, Baerbel Tiemeyer, Mirjam Helfrich |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250091957
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| Publikation (Nr.) |
 EGU/EGU2014-6277.pdf |
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| Zusammenfassung |
| Soil fertility of agricultural soils is challenged by nutrients losses and increasing soil
acidification. Furthermore, leached nutrients negatively affect the quality of ground and
surface water 1]. In addition to the possible soil carbon sequestration by applying biochars,
many positive soil-improving properties are attributed to biochars. The application of
biochars to agricultural – especially sandy – soils could reduce leaching of nutrients
and may improve their availability 1,2]. Thus, biochar application to agricultural
fields could be an ecologically and economically viable option to improve soils’
fertility.
However, biochar properties strongly depend on their feedstock and production process
3]. Various types of biochars (pyrolysis char, hydrochar (produced at 200 and 250°C);
feedstocks: digestate, Miscanthus and wood chips) were used to determine sorption kinetics
and sorption isotherms for the major nutrients Ca, Mg, K, NH4 and NO3 as a function of
biochar types in different soil substrates (sand, loess). In addition, the biochars were washed
to create free binding sites on the chars’ surface that simulate aged char. We compared the
simulated aged char with biochars that was aged in-situ at a field experiment for seven
months.
The first results showed that pyrochars have the largest retention potential for NO3 and
hydrochars have retention potential for NH4. Washing of biochars turned them from a PO4
and NH4 source into an adsorber, especially for hydrochars. Highest leaching was
observed for biochars from digestates likely due to the high nutrient content of
digestates. But the different ions may lead to pH-dependent interactions between each
other and the chars’ surface that override the adsoption effects. In this context,
cation-bridge and ligand bindings 4,5] need to be further investigated. Most of the fresh,
unwashed biochars were a source of nutrients with hardly any detectable nutrient
retention.
Pyrochars showed the highest potential for anion-retention and hydrochar was effective in
cation-retention. The experiments provide first information on the uses of biochar for soil
nutrient management in agriculture but observed effects were mostly minor under realistic
char application rates.
[1] LIANG ET AL. 2006: Black Carbon increases cation exchange capacity in soils. SSAJ
70, 1719-1730.
[2] LEHMANN ET AL. 2009: Biochar for Environmental Management – Science and
Technology. 1 An Introduction, 1.
[3] YAO ET AL. 2012: Effect of biochar amendment on sorption and leaching of nitrate,
ammonium, and phosphate in a sandy soil. Chemosphere 89, 1467-1471.
[4] MUKHERJEE & ZIMMERMANN, 2011: Surface chemistry variations among a series
of laboratory-produced biochars. Geoderma 163, 247-255.
[5] QIAN ET AL. 2013: Effects of environmental conditions on the release of phosphorus
from biochar. Chemosphere 93, 2069-2075. |
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