Effect of some biological factors on soil variability in the tropics

Abstract

Field observations were carried out on an Egbeda soil series in western Nigeria to study the degree of soil-nutrient variability within and between plots due to pre-clearing vegetation. The soil showed lower soil pH, organic C, exchangeable K and Ca contents following cassava grown by traditional methods than following secondary forest vegetation or thicket regrowth. Except for exchangeable K, the degree of variability of the above parameters was observed to be ill the following order: secondary forest vegetation > thicket regrowth > cassava plots. The available P status was generally low and showed little relation to pre-clearing vegetation. The implications of soil variability due to pre-clearing vegetation on soil sampling and in field experimentation are discussed.

Phosphorus forms in Brazilian termite nests and soils: Relevance of feeding guild and ecosystems

“…Studies on available P fractions in termite nests used a variety of extraction methods. The commonly used Bray and Olsen extractions showed an accumulation of available P in mounds compared to adjacent soils for soil-feeding termites (Wood et al, 1983;Ndiaye et al, 2003) and depletion for fungus-growing termites (Kang, 1978;Arshad, 1981). Aside from López-Hernández et al (2006), who studied the effect of several feeding groups on water-soluble P, reports on other feeding guilds are scarce, and only one international published report listed the impact of termites on P in Brazil (Fageria and Baligar, 2004).…”

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

“…Depending on the dominant species and mound size there is a maximum mound density per unit area (Lee and Wood, 1971). Hence, so long as an area is habitable by termites, faunalturbation will continue to impact soil development and variability (Kang, 1978;Wood et al, 1983;Umeh et al, 1999;Jouquet et al, 2005;Obi, 2006) at near constant spatial scales. This process continues over a period that ranges from hundreds to thousands of years (Lal, 1987(Lal, , 1988Hulugalle and Ndi, 1993;Lobry de Bruyn and Conacher, 1995) and could serve as source of within-field variability of soil properties (i.e.…”

Soil-particle selection by the mound-building termiteMacrotermes bellicosuson a sandy loam soil catena in a Nigerian tropical savanna

“…Email: s.abe@cgiar.org influences termite nest-building activity. In fact, number and volume of termite mounds are often found to be lower in the lowlands than the uplands (Abe et al 2009, Kang 1978. The objective of this paper, therefore, was to examine effects of toposequence on soil-particle selection by Macrotermes bellicosus, a dominant species in Nigerian tropical savanna.…”