Influence of termite infestation on the spatial variability of soil properties in the Guinea savanna region of Nigeria

• Published in: Geoderma 2009-01, Vol.148 (3), p.357-363
• Main Authors: Obi, Jude C., Ogunkunle, Ayo. O.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Coefficient of variation; Earth sciences; Earth, ocean, space; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Guinea savanna; Isoptera; Soils; Spatial variability; Surficial geology; Synecology; Termite infestation; Terrestrial ecosystems
• ISSN: 0016-7061; 1872-6259
• DOI: 10.1016/j.geoderma.2008.11.003

Soil spatial variability affects the precision of statements about soil properties, behaviour and land use. Termites feed, construct and repair their nests from organic and inorganic components of the soil and through these activities influence soil formation processes and consequently contribute to soil variability as a point centered pedoturbation process. The objective of this study is to evaluate the influence of termites on the spatial variability of soil physical and chemical properties in the Guinea savanna region of Nigeria, using geostatistics, which have been found to be suitable for investigating spatial variability in comparison with classical statistics. Routine soil parameters were measured in the 0–15 cm depth of 20 m × 20 m grid samples in two termite infested and one non-infested plot (each measuring 100 m × 100 m) in Mokwa and Kontagora areas of Niger State, Nigeria. On average, 73.3% and 66.7% of the soil properties in the infested and non-infested plots respectively of Mokwa, and 70.0% and 93.3% of the soil properties in the infested and non-infested plots respectively of Kontagora had coefficients of variation < 35%. Using maximum R 2, models were fitted to the semivariograms. The magnitude of positive nugget effect displayed by most soil properties as a result of termite infestation (i.e. within the range of 0.002–0.009) was about 100 times lower than those of non-infested (i.e. within the range of 0.008–0.02) in Mokwa. The particles size distribution of the soils were significantly correlated and display strong spatial dependence in the infested plots of Mokwa as indications of intrinsic variation attributable to point centered pedoturbation of termites. Termites contribute to short range variability of soils texture in Mokwa area of Nigeria, which was observed at 20 cm interval while shorter sampling interval may be necessary in Kontagora. Hence inter-termiterial distance could be a determinant in extent of spatial variability.