Abstract

The effects of soil compaction on plant productivity were studied in the dry season of September 2008 in Umfolozi catchment, South Africa. This study used 10 paired plots each measuring 20 x 20 m and 1 x 1 m quadrats randomly located within the study plots in both degraded and undegraded sites. Soil samples were collected on the outer edge of the quadrats within the study plots. Soil moisture (%) in the soil samples collected from the degraded and undegraded sites was 8.94 and 13.48%, respectively. Organic matter (%) was 3.17 and 5.46% on degraded and undegraded sites, respectively. Average soil bulk density (g/cm^-3) was 0.99 g/cm^-3 (CV=1.81 %) and 0.83 g/cm^-3 (CV=5.02 %) on degraded and undegraded sites, respectively. Porosity was greater on undegraded sites (36.2%) than on degraded sites (34.2%). Seedling density (no/pot) was 18 seedlings per pot in soil samples collected on degraded and 10 seedlings per pot on undegraded sites. Seedling mortality (no/pot) was 17 seedlings per pot and 9 seedlings per pot in the soil samples collected on degraded and undegraded sites, respectively. Spearman rank correlation showed strong correlation between seedling density and soil compaction (r=-0.481, P<0.05). Seedling emergency density (no/pot) reached highest level on degraded sites compared to undegraded sites. Seedling mortality (no/pot) reached highest level on degraded sites. The study suggests that soil compaction and soil bulk density are critical for an efficient resource management in rangelands.

Key words: Soil density, soil compaction, degraded landscapes, semi-arid areas.