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N.P.Buchkinaand E.V.Balashov
Influence of a Grass-Clover Mixture onSOM
3.15
The Influence of a
Grass-Clover Mixture on Soil
Organic Matter and
Aggregation of a Podzolic
Loamy Sand Soil
N.P. B
UCHKINA AND
E.V. B
ALASHOV
AgrophysicalResearch Institute, 14GrazhdanskyProspect, St
Petersburg 195220, Russia
Introduction
Sustainable land use is fundamentally dependent on maintaining adequate
concentrations of soil organic matter. Organic matter is known to be
essential in the self-regeneration of soil structure, water-stable aggregation,
water holding and air capacity following mechanical damage to soils. Two
main mechanisms have been proposed to explain the physical protection
of organic matter against decomposition: association with clay particles
and occlusion within aggregates (Hassink
et al
., 1993; Golchin
et al
., 1995).
The stabilization of organic matter within soil micro- and macroaggregates
is closely related to the water-stable aggregation, which is one of the key
indicators of sustainable land use. This parameter has been found to be
sensitive to the effects of different tillage systems, crops and organic
fertilizers (Ekwue, 1990; Franzluebbers and Arshad, 1997).
At present, only low rates of animal manure are incorporated into
arable soils in Russia. An increasing use of perennial vegetation and
green manure instead of animal manure is being observed in the current
management practices in the northwestern region of Russia. A critical
problem is whether soil quality can be maintained with the use of perennial
grass-clover mixtures as organic fertilizers.
The objective of the present study was to estimate the effects of a
seven-course rotation on the relationships between the size distribution of
water-stable aggregates and organic matter content in a light-textured
podzolic soil under two diverse tillage treatments. Discussion is restricted to
the data for the organic matter content of the whole soil and aggregates and
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