**3.1.1 Peat content**

Soil loss decreased with increasing levels of peat in the three soils. This was true irrespective of the compaction effort, and the rainfall duration that the three soils were exposed to. The decrease in soil loss by peat content confirms the earlier findings in the previous papers by Ekwue et al. (2009) and Ekwue and Harrilal (2010) that peat decreases soil erosion by water. This can be attributed to its reduction of soil bulk density (Table 6).


Table 3. Surface runoff (mm) of soils at varying peat, compaction levels and rainfall durations

This is in line with the findings of Ekwue and Stone (1995) and Ekwue et al. (2009) which showed that peat reduces bulk density of soils by diluting the soil matrix with its own less dense material. This reduction in soil bulk density ensured that peat increased the infiltration capacity of the soils, and therefore reduced runoff and soil loss as was further confirmed in this study (Tables 2, 3, and 4). Ekwue (1987, 1992) reported increases in infiltration rates as a result of peat incorporation to the soil. Table 6 shows that penetration resistance decreased with increasing peat contents in all the soils. This result is in agreement with the findings of Ekwue (1990) and Zhang et al. (2005) which showed that peat reduces soil strength. Peat reduces soil strength by just adding to the soil bulk, reducing its inter-aggregate stability and making the soil aggregates to fall apart (Ekwue, 1987). Although soil strength is known to increase the resistance of soils to erosion (Rachman et al., 2003; Wuddivira, 2008), the present results further confirm that peat reduces soil loss by increasing infiltration and decreasing runoff during rainfall rather than by strengthening the soil as was obtained for other organic materials like farmyard manure by Wuddivira et al. (2009) and Ekwue et al. (2009). Runoff and soil erosion are important not only for soil and water conservation, but also to reduce nutrient discharge with runoff (Bjorneberg et al., 2000). This means that the reduction of surface runoff and soil erosion by peat will not only aid soil conservation, but also reduce loss of plant nutrients in the soil. The interaction between peat content and rainfall duration (Fig. 3) shows that the effect of peat on soil loss increases with rainfall duration. A similar interaction was reported for soil detachment by Ekwue (1991) in connection to organic matter originating from grass.
