Texture is the finest or coarseness of the soil material that are equivalent to less than 2.00mm in diameter and structural stability describes the ability of the soil to retain its arrangement of aggregates and pore space when exposed to external stress such as wetting and cultivation. Thus this study evaluates the effect of soil texture and period of soaking in aggregate stability of four major soils textural classes in south eastern, Nigeria. Both the wet and dry sieving techniques were used. The soil textures used include sandy loam, sandy clay loam, clay loam and loam under five periods of soaking namely, 0, 30, 90 and 120 minutes. Aggregate stability indices evaluated include mean weight diameter wet (MWDW), water stable aggregates > 2.00mm. (WSA 1), water stable aggregates 2.00 – 1.00mm (WSA 2), water stable aggregates 1.00 – 0.500mm (WSA 3) water stable aggregates 0.500 – 0.25mm (WSA 4) water stables aggregates < 0.25mm (WSA 5). Also mean weight diameter dry (MWDD), dry stable aggregates > 2.00mm (DSA 1) dry stable aggregates 2.00 – 1.00mm (DSA 2), dry stable aggregates 1.00 – 0.500mm (DSA 3) dry stable aggregates 0.500 – 0.25mm (DSA 4) dry stable aggregates < 0.25mm (DSA 5). The findings from the study showed that texture was a significant (P < 0.05) controlling factor in the formation and stability of soil aggregates. The mean weight diameter (MWD) of clay loam with respect to textures used in the study was significantly lowest in wet sieving probably because it is prone to disintegration when wet than when dry and thus disappears more easily into water than the other textures. Period of soaking showed non-significant effect with all the indices used but this only means that its contribution is not much to be verified by statistical analysis.
Keywords: Aggregates, mean weight diameter, texture, soaking, soil structure