中国科学院水利部水土保持研究所机构知识库

Background. Long-term fertilisation has a large influence on soil physical and chemical
properties in agro-ecosystems. The effects on the distribution of aggregates, however,
are not fully understood. We determined the dynamic change of the distribution
of aggregates and soil organic carbon (SOC) content over time in a long-term field
experiment established in 1998 on the Loess Plateau of China and illustrated the
relationship between them.
Methods. We determined SOC content and the distribution of aggregates in nine
fertiliser treatments: manure (M); nitrogen (N); phosphorus (P); M and N; M, N, and
P; M and P; N and P; bare land; and an unfertilised control. These parameters were
then used for a path analysis and to analyse the fractal dimension (Dv).
Results. The organic fertiliser increased SOC content. The proportions of 0.10.25mm
microaggregates and 0.250.5 mm macroaggregates were higher and the proportion of
the 0.010.05 mm size class of the silt C clay fraction was lower in the treatments
receiving organic fertiliser (M, MN, MNP, and MP) than that in the control, indicating
that the addition of organic fertiliser promoted aggregation. The distribution of
aggregates characterised by their fractal dimension (Dv ), however, did not differ among
the treatments.
Discussion. Dv was strongly correlated with the proportion of the <0.002 mm size
class of the silt C clay fraction that did not differ significantly among the treatments.
The change in the distribution of aggregates was strongly correlated with SOC content,
which could produce organic polymer binding agents to increase the proportion of
larger particles. Long-term application of organic fertiliser is thus necessary for the
improvement and maintenance of soil quality in semi-arid agricultural land when
residues are removed.