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SP14-16
Influence of mature cassava roots on structural stability and
polysaccharide content of some upland soils in southern
Nigeria
Sunday E. Obalum1*, Gloria I. Ezenne2 and Leonard D. Ekeleman1
1
Dept. of Soil Sci. & Land Resour. Manage., 2Dept. of Agric. & Bioresour. Engineering;
University of Nigeria, Nsukka 410001, Enugu State, Nigeria
*[email protected] Registrant ID# 4764
In the course of their growth, cassava (Manihot spp.) roots exert pressure on the soil
through which they pass and the influence of such pressure on soil structure is expected to
be most pronounced at maturity, when the roots also have high content of polysaccharide
which is known to play important role in soil structure stabilizing effect of organic matter.
Yet, little is known about how cassava roots influence the structural stability of the soil in
contact with them. Cassava is among the most cultivated crops in southern Nigeria where it
is mostly grown in drained upland soils where organic matter, due to its low concentration in
the soil, contributes only very little to soil structural stability. In this study, roots of mature
cassava growing on mounds and soils adhering to them were sampled alongside soils from
other parts of the mounds and from furrows in three cassava-growing environments (Nando,
Adani and Nsukka) in southern Nigeria. The objective was to check for any effect of root
contact with soil all through the growing season on structural stability of the soil, and to
understand the role of polysaccharide content of the soil in causing such effect. The soils,
which differed markedly in texture, have been analysed for structural stability while the
analyses of the soils and cassava roots for organic matter and polysaccharide contents are
ongoing. Appropriate statistical analyses will be applied to the data to test for differences in
structural stability and polysaccharide content of soils in contact with roots and those at the
furrows. The results are expected to show higher stability in the former than the latter as
well as an association between stability and polysaccharide content of the soil which will be
stronger for soils in contact with roots than for those at the furrows. The agronomic and
environmental implications of the results will be discussed.