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| Titel |
Impact of rice-straw biochars amended soil on the biological Si cycle in soil-plant ecosystem |
| VerfasserIn |
Zimin Li, Bruno Delvaux, Eric Struyf, Dácil Unzué-Belmonte, Frederik Ronsse, Jean-Thomas Cornelis |
| 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 |
250152406
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| Publikation (Nr.) |
 EGU/EGU2017-17238.pdf |
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| Zusammenfassung |
| Biochar used as soil amendment can enhance soil fertility and plant growth. It may also
contribute to increase the plant mineralomass of silicon (Si). However, very little studies have
focused on the plant Si cycling in biochar amended soils. Here, we study the impact of two
contrasting biochars derived from rice straws on soil Si availability and plant Si uptake. Rice
plants were grown in a hydroponic device using Yoshida nutrient solution, respectively
devoid of H4SiO4 (0 ppm Si: Si-) and enriched with it (40 ppm Si: Si+). After 12 weeks, the
plants were harvested for further pyrolysis, conducted with holding time of 1h at
500˚ C. The respective rice-biochars are Si-/biochar and Si+/biochar. They exhibit
contrasting phytolith contents (0.3 g Si kg−1 vs. 51.3 g Si kg−1), but identical
physico-chemical properties. They were applied in two soils differing in weathering
stage: a weathered Cambisol (CA) and a highly weathered Nitisol (NI). We then
studied the effects of the amended biochar on CaCl2 extractable Si using a 64-days
kinetic approach, on the content of soil biogenic Si, and on the uptake of Si by
wheat plants grown for 5 weeks. We also quantified Si mineralomass in plants. We
compared the effects of biochars to that of wollastonite (Wo)–(CaSiO3), a common
Si-fertilizer.
Our results show that Si+/biochar significantly increase the content of BSi in both soils.
In CA, the cumulative content of CaCl2 extractable Si amounts to 85 mg kg−1 after
Si+/biochar amendment, which is below the amount extracted after Wo application (100 mg
kg−1). In contrast, in NI, the cumulative content of CaCl2 extractable Si is 198 mg kg−1 in
the Si+/biochar amended treatment, which is far above the one measured after Wo application
(93 mg kg−1). The Si-/biochar has no effect on the cumulative content of CaCl2 extractable
Si in either soil type.
Biochars and wollastonite increase the biomass of wheat on both soils. The increase is,
however, larger in NI than in CA. In terms of Si uptake by wheat , Si-/biochar does not
increase the Si content of plants in either soil type. As expected, Si+/biochar and wollastonite
significantly increase the Si content of wheat plants grown on both soils. The increase caused
by Si+/biochar is, larger in NI (10 mg Si pot−1) than that in CA (5 mg Si pot−1). This result
is in line with the release of CaCl2 extractable Si in both soils amended by Si+/biochar,
confirming the validity of CaCl2-extraction to estimate the pool of bioavailable
Si.
Our data highlight that phytolith-rich biochar readily contributes to the pool of
bioavailable Si, further taken up by plant roots, and increases Si mineralomass in plants as
well as plant growth. Thus it provides an alternative to wollastonite application. The effect
is particularly large in the highly weathered Nitisol. Under such conditions, the
impact of phytolith rich biochar is not limited to the enhancement of Si biological
cycle, but is extended to the increase of soil pH, CEC and organic matter content. |
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