Conventional agriculture is one of the widely adopted agricultural practices globally with an
aim to increase production. This practice effectually increases yields, but with a growing array
of environment and health concerns. Organic agriculture is reflected as a "sustainable
substitute" for conventional agriculture, this phenomenon was investigated in this study by
comparing the patterns of diversity and community structure of soil macrofauna as well as their
relations with soil properties in organic and conventional ecosystems. Macrofauna was selected
as model organisms for this study because these fauna groups are sensitive to changes in their
environment and changes in their community structure offer an integrative assessment of
ecosystem effects. Soil macrofauna were sampled using standardised procedures of Tropical
Soil Biology and Fertility, in organic, intercropped and conventional wheat agroecosystems.
The results show that the studied soil macrofauna groups, with an exception of Hymenoptera
termites, are negatively affected by the intensity of conventional management, the organic and
the intercropped systems exhibited similarities in species distributions, this was attributed to
the cultural management practices applied to these systems where livestock manures and
mulches, as well as practices such as no-till, are incorporated into the soil. Results obtained
from the soil characterisation and analysis revealed that the dissimilarities in agroecosystem
management have a significant influence on soil physicochemical properties, which
consequently influences the distribution of the macrofauna assemblages. Stable isotopes did
not reveal any significant differences between the systems, however macrofauna taxa, plant
and soil samples from the organic systems were rich in natural abundance stable isotopes
signatures, this aspect needs further investigation through extensive sampling under long term
experiments, to observe clear differences. The general results of this study show that organic
farming as an agricultural management strategy is the most stable system that positively
supports the diversity in the soil macrofauna community and soil physicochemical properties
as compared to the conventional system. Macrofauna diversity and functioning in the soil are
affected by conventional agriculture, this may have negative implications for nutrient cycling
and soil health in ecosystems cultivated under conventional monoculture, tillage and chemical
intensifications. Continual research would be imperative to discover how the soil macrofauna
contributes to ecosystem function and how they affect the soil ecosystem itself. / College of Agriculture and Environmental Sciences
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:unisa/oai:uir.unisa.ac.za:10500/26896 |
| Date | 01 1900 |
| Creators | Mamabolo, Emogine |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Format | application/pdf |
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