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| Titel |
Assessing the strength of soil aggregates produced by two types of organic
matter amendments using the ultrasonic energy |
| VerfasserIn |
Zhaolong Zhu, Budiman Minasny, Damien Field, Denis Angers |
| 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 |
250138945
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| Publikation (Nr.) |
 EGU/EGU2017-2094.pdf |
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| Zusammenfassung |
| The presence of organic matter (OM) is known to stimulate the formation of soil aggregates,
but the aggregation strength may vary with different amount and type/quality of OM.
Conventionally wet sieving method was used to assess the aggregates’ strength. In this study,
we wish to get insight of the effects of different types of C inputs on aggregate dynamics
using quantifiable energy via ultrasonic agitation. A clay soil with an inherently low soil
organic carbon (SOC) content, was amended with two different sources of organic matter
(alfalfa, C:N = 16.7 and barley straw, C:N = 95.6) at different input levels (0, 10, 20, & 30 g
C kg−1 soil). The soil’s inherent macro aggregates were first destroyed via puddling. The
soils were incubated in pots at moisture content 70% of field capacity for a period of
3 months. The pots were housed in a 1.2L sealed opaque plastic container. The
CO2 generated during the incubation was captured by a vial of NaOH which was
placed in each of the sealed containers and sampled per week. At 14, 28, 56, and
84 days, soil samples were collected and the change in aggregation was assessed
using a combination of wet sieving and ultrasonic agitation. The relative strength
of aggregates exposed to ultrasonic agitation was modelled using the aggregate
disruption characteristic curve (ADCC) and soil dispersion characteristic curve (SDCC).
Both residue quality and quantity of organic matter input influenced the amount of
aggregates formed and their relative strength. The MWD of soils amended with
alfalfa residues was greater than that of barley straw at lower input rates and early
in the incubation. In the longer term, the use of ultrasonic energy revealed that
barley straw resulted in stronger aggregates, especially at higher input rates despite
showing similar MWD as alfalfa. The use of ultrasonic agitation, where we quantify
the energy required to liberate and disperse aggregates allowed us to differentiate
the effects of C inputs on the size of stable aggregates and their relative strength. |
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