Global Change Abstracts The Swiss Contribution - SCNAT

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separation were increased. Trafficking had no
clear effect on the orientation of pores. While the
mean pore diameter tended to decrease, biopores
were more stable than interaggregate pores originating
from the packing of soil aggregates. This
is relevant for the development of structural stability
in restored soils, as the macro-pores consist
mainly of interaggregate pores initially, whereas
biopores develop and increase in proportion only
gradually over time. Quantitative morphometry
provides valuable morphological indices for the
objective assessment of the macro-pore structure
and changes induced by compaction.
European Journal of Soil Science, 2007, V58, N5,
OCT, pp 1062-1073.
08.1-212
Reducing phosphorus losses from over-fertilized
grassland soils proves difficult in the
short term
Schärer M, Stamm C, Vollmer T, Frossard E, Oberson
A, Flühler H, Sinaj S
Switzerland
Water Resources , Agriculture, Soil Sciences , Toxicology
, Hydrology
Phosphorus (P) losses from many agricultural
soils are driven by fast transport processes, such
as surface runoff, shallow interflow and macropore
flow. Close interaction of rain with topsoil layers
(0-5 cm), rich in available P, results in high P
concentrations in these rapid runoff pathways.
This is particularly pronounced in permanent
grassland soils typically characterized by a P enrichment
of the topsoil. One option to mitigate P
losses from grassland is therefore to reduce soil
P content, particularly available P, in this critical
surface layer. Omitting application of P fertilizer
will reduce soil P in the long term but more drastic
methods may be necessary to achieve P loss
reductions in shorter time-scales. In this study,
three management options to reduce P in runoff
from grassland soils were evaluated in a field experiment
lasting 2 years on two grassland sites: (i)
no P inputs, (ii) no P inputs plus soil tillage and
(iii) no P inputs plus tillage combined with application
of a P sorbing soil amendment (iron oxide).
Withholding P inputs did not decrease either the
available P in the soil or the P concentrations in
runoff from sprinkler experiments over a 2-year
period. Both the treatments which included tillage
caused immediate reductions in both soil
available P and runoff P, with Fe/OH amendment
being more effective. However, in the second year
the effects of both tillage treatments were less apparent
and only the Fe/OH treatment significantly
decreased runoff P. The results indicate that the
Global Change Abstracts – The Swiss Contribution | Soil and Lithosphere
long-term enrichment of soils due to P application
in excess of plant needs is unlikely to be remedied
by short-term treatments. However, further
work is required to assess the applicability of our
conclusion to other sites.
Soil Use and Management, 2007, V23, SEP, S1, pp
154-164.
08.1-213
Heavy metal contamination along a soil
transect in the vicinity of the iron smelter of
Kremikovtzi (Bulgaria)
Schulin R, Curchod F, Mondeshka M, Daskalova A,
Keller A
Switzerland, Bulgaria
Agriculture, Soil Sciences , Toxicology , Geochemistry
& Geophysics
Based on previous preliminary survey results,
elevated heavy metal concentrations of the agricultural
soils of the villages of the Kremikovtzi
region east of the Bulgarian capital Sofia were
attributed to pollution from dusts emitted by
the iron smelter in the centre of the region. Additional
sampling in a test area indicated that
high metal concentrations in this area could also
be of geogenic origin. In order to test this hypothesis,
we sampled a sequence of 14 soil profiles at
increasing distance from the smelter along a 2
km transect through agricultural land outside
the metallurgical complex of Kremikovtzi. The
transect extended through two different units of
soil types: Chromic Luvisols and Alluvial Fluvisols.
Samples of the fine earth fraction (