Flood variation and soil nutrient content in floodplain vegetation communities in the Okavango Delta

The authors have investigated the influence of hydroperiod variation on soil nutrient content in the Okavango Delta seasonal floodplains. Soil samples were collected from eight zones of homogenous vegetation cover after low and high floods and analysed for pH, Na, Mg, Ca, K and P content. A Student's t-test was used to test for differences in pH, Na, Mg, Ca, K and P between soils after low and high floods. The Kruskal-Wallis test was used to compare means of flooding duration and depth between low and high floods. Na, K, Mg, P and pH levels in soils were significantly different after low floods compared with after high floods. Na content was lower in Zones 2 and 8 and higher in Zones 4, 5 and 6 during high flood than during low flood. Ca content was lower in Zones 1, 2, 3, 4 and 5 and higher in Zone 7 under high flood than during low flood.