Nzeako Sidney.O
A study to determine the influence of agro-related anthropogenic activities on soil nematode spatial distribution in the Niger Delta was carried out in three designated areas with different cropping practices. Soil samples were randomly collected from the Niger Delta Development Commission (NDDCF) farm: mixed-cropping (Site A); Rivers State Oil Palm (RISOPALM) plantation: mono-cropping (Site B); and the University of Port Harcourt Botanical Garden (UPHBG): an undisturbedsite(Site C). Soil samples were collected at 0-5cm, 5-10cm and 10-15cm depths per core using a modified 5cm diameter soil auger. The Baermann’s extraction technique was used to recover nematodes from the samples. A total of 458 nematodes were recovered comprising 13 species out of which 249(54.3%) nematodes of 11species came from Site C; Site B yielded 168(36.6%) nematodes of 4 species while Site A yielded 41(8.9%) nematodes. There was variability in nematode assemblage in relation to specific core depths (p>0.05). The overall nematode abundance and diversity was highest at depth 0-5cm(52.6%) followed by depth 5-10(35.5%) and depth 10-15cm(11.7%). The depth related decline in nematode species diversity and abundance was associated with nutritional affiliations of the nematode species and the level of agro-related anthropogenic interference. However, specialist nematode species distribution was influenced by specific host factors while the distribution of the generalist nematode species were influenced by specific environmental factors. Mix-cropping and mono-cropping were major anthropogenic activities that influenced nematode distribution. The study also revealed that mono-cropping influenced the specialist nematodes while mix-cropping generally declined nematode species abundance and richness which could be exploited as a control measure against specific parasitism of crops especially in the Niger Delta where subsistent agriculture prevails.
