FACTORS INFLUENCING THE RELATIONSHIP BETWEEN NEMATODE COMMUNITIES AND EDAPHIC FACTORS ON SELECTED SOIL GROUPS IN KENYA: VERTISOLS, CAMBISOLS AND ARENOSOLS

Abstract

Background. Inappropriate agricultural practices such as use of heavy machinery, excessive tillage and unbalanced use of inorganic fertilizers, inappropriate irrigation practices and poor water management techniques, pesticide overuse, inadequate crop residue and/or organic carbon inputs, and poor crop cycling negatively affect soil characteristics. Objective. Determine the relationship between soil physical-chemical parameters and nematode assemblages, ecological suitability and nutrient recycling potential as influenced by their respective soil ecosystems. Methodology. A total of 576 soil samples were collected in areas characterized by small scale subsistence agriculture in Kenya’s Northern and Southern sites during the cold-dry (1), warm-rainy (2) and hot-dry (3) seasons. The sampling points included land under cultivation (disturbed) and the adjoining natural undisturbed land within three soil groups, namely; Vertisols, Cambisols and Arenosols. Nematodes were extracted, assigned to their respective trophic groups and correlated with analyzed soil chemical properties. Results. Omnivores and predators were positively influenced by an increase in Mg and soil organic matter content while an increase in soil pH, K and NH4 contenthad a linear relationship with bacterivores. Increase in Ca and N concentrations was associated with increased numbers of both herbivores and fungivores. Low ecological disturbance and nutrient cycling potential was favored in natural soils, northern sites and where the soils had an active root growth in season 2. Implications. Sustainable soil management practices are recommended in a bid to maintain the favorable soil structure through nematode assemblage. Conclusion. Changes in soil properties resulting from anthropogenic activities, have a significant impact on nematode assemblages in their respective food webs.