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Understanding the effects of these perturbations on soil physicochemical and
microbiological properties can provide essential information for assessing
sustainability and environmental impact (Rahman et al., 2008). Changes in land use
and land cover often alter ecosystem structure and function, which, in turn, affect
above- and below-ground processes and contribute to global change (Hollister et al.,
2010). When several land use-biodiversity loss gradients were compared, it was
shown that ecosystem quality decreases as agricultural practices intensify (Reidsma et
al., 2006).
Changes in land use, such as from forests to pasture, can have significant and long-
lasting effects on soil nutrients, carbon content, soil texture and pH. These effects are
largely as a result of changes in the composition of plant species and associated
management practices across land use types (Lauber et al., 2008). In addition,
applications of chemical fertilizers have been reported to change soil bacterial
community structure significantly (Wang et al., 2008). It has also been observed that
tillage, over-grazing and pollution, which reduce aboveground plant diversity, cause
microbial variation to decrease (Kennedy and Gewin, 1997). Removal of crop plants,
which results in plant-induced changes in the soil microbial community, has been
shown to affect the follow-on crop (Heuer et al., 2002).
Soil has a considerable capacity for diversity and hence a great buffering capacity
before the effects of management practices on dominant community members are
seen (Girvan et al., 2003). By understanding how agricultural land use and
management practices may alter soil quality and affect the diversity of soil microbial
populations, lower-input sustainable systems may be developed (Purkhold et al.,
2000; Rahman et al., 2008).
2.3.2.1 Arable agriculture
Land degradation reduces the productive capacity of arable agricultural soils causing
a loss of biodiversity. However, land use management practices, such as tillage
methods, crop residue management, application of fertilizers and manures, can help
minimise this deterioration (Girvan et al., 2003).
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