Ayuke, F.O., Brussaard, L., Vanlauwe, B., Six, J., Lelei, D.K., Kibunja, C., Pulleman, M.M. (2011). Soil fertility management: impacts on soil macrofauna, soil aggregation and soil organic matter allocation

Citation:
Ayuke FO, Brussaard L, Vanlauwe B, Six J, Lelei DK, Kibunja C, Pulleman MM. "Ayuke, F.O., Brussaard, L., Vanlauwe, B., Six, J., Lelei, D.K., Kibunja, C., Pulleman, M.M. (2011). Soil fertility management: impacts on soil macrofauna, soil aggregation and soil organic matter allocation." Applied Soil Ecology. 2011;48:53-62.

Abstract:

Maintenance of soil organic matter through integrated soil fertility management is important for soil
quality and agricultural productivity, and for the persistence of soil faunal diversity and biomass. Little
is known about the interactive effects of soil fertility management and soil macrofauna diversity on
soil aggregation and SOM dynamics in tropical arable cropping systems. A study was conducted in a
long-term trial at Kabete, Central Kenya, to investigate the effects of organic inputs (maize stover or
manure) and inorganic fertilizers on soil macrofauna abundance, biomass and taxonomic diversity, water
stable aggregation, whole soil and aggregate-associated organic C and N, as well as the relations between
these variables. Differently managed arable systems were compared to a long-term green fallow system
representing a relatively undisturbed reference.
Fallowing, and application of farm yard manure (FYM) in combination with fertilizer, significantly
enhanced earthworm diversity and biomass as well as aggregate stability and C and N pools in the top
15cm of the soil. Earthworm abundance significantly negatively correlated with the percentage of total
macroaggregates and microaggregates within macroaggregates, but all earthworm parameters positively
correlated with whole soil and aggregate associated C and N, unlike termite parameters. Factor analysis
showed that 35.3% of the total sample variation in aggregation and C and N in total soil and aggregate
fractions was explained by earthworm parameters, and 25.5% by termite parameters. Multiple regression
analysis confirmed this outcome.
The negative correlation between earthworm abundance and total macroaggregates and microaggregates
within macroaggregate could be linked to the presence of high numbers of Nematogenia lacuum
in the arable treatments without organic amendments, an endogeic species that feeds on excrements of
other larger epigeic worms and produces small excrements. Under the conditions studied, differences
in earthworm abundance, biomass and diversity were more important drivers of management-induced
changes in aggregate stability and soil C and N pools than differences in termite populations.
Keywords: Earthworm, Termite, Taxonomic richness, Soil organic matter, Carbon, Nitrogen, Soil aggregate fraction

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