Chemistry Reference
In-Depth Information
interactions between agricultural management practices and soil fauna (e.g.
termites) in order to find ways to enhance soil fertility and crop yields.
Soil microorganisms are a source of important medicines, including most of
the early antibiotics such as penicillin. But despite their functional importance,
the soil biota remain a ''black box'' to scientific understanding as well as to the
common gaze due to a number of challenges which include lack of appropriate
methods to study this myriad of organisms and their complex ecosystem. The
role they play in determining some crucial ecological functions has resulted in a
shift in the way scientists view them and there is a major attempt to amass
knowledge so as to exploit them for development of sustainable utilisation and
management of soil resource. It is against this background that the Global
Environment Facility-United Nations Environment Programme (GEF-UNEP)-
funded global project on the conservation and management of below-ground
biodiversity (CSM-BGBD) was conceived.
d
n
1
r
2
n
g
|
4
5
Case Studies: Effect of Management and/or Land Use
Intensification
5.1 Soil Carbon as Fuel for Soil Organisms
Maintenance of soil organic matter (SOM) through integrated soil fertility
management is important for soil quality and agricultural productivity, and for
the persistence of soil faunal diversity, abundance and biomass. In turn, soil
macrofauna affect SOM dynamics through organic matter incorporation,
decomposition and the formation of stable aggregates that protect organic
matter against rapid decomposition.
Integrated soil fertility management (ISFM), widely advocated in sub-
Saharan Africa, recognises the benefits of combining organic and inorganic
fertilisers for sustainable nutrient management.
51,52,56
The beneficial effect of
soil organic matter (SOM) on soil productivity through supplying plant
nutrients, enhancing cation exchange capacity, improving soil aggregation and
soil and water retention, is well established.
53-55
In addition, SOM supports
various soil biological processes by being a substrate (source of carbon) for
decomposer organisms and ecosystem engineers, such as earthworms and
termites that play an important role in soil structure formation, organic matter
decomposition and nutrient mineralisation.
53,54
Ayuke et al.
56
showed that
arable cropping has significant negative effects on earthworm, but little effect
on termite diversity as compared to long-term fallow. Under continuous crop
production, higher earthworm and termite diversity was observed under
agricultural management that had resulted in high-C versus low-C soils.
To reiterate the benefits of ISFM as promoter of soil biodiversity, Ayuke et
al.
57
demonstrated that long-term application of manure in combination with
fertiliser result in higher earthworm taxonomic richness and biomass (see
Table 4), which leads to improved soil aggregation and enhanced C and N
stabilisation within this more stable soil structure.
57
It is possible that the long-
