The relationship between soil morphology and soil water regime: preliminary results in the Weatherley catchment

Abstract

Soil water contents were measured for five years at Weatherley, an intensively instrumented catchment in the north eastern part of the Eastern Cape Province. Soil water contents are expressed in terms of average duration of saturation with water above 0.7 of porosity (AD_S>07 in days per year) and is related to soil morphology. Preliminary results indicate that different orthic A horizons can have AD_S>0.7 from 3 to 356 days per year, depending on the nature of the underlying horizons. The E and soft plinthic B horizons in the Longlands profile had AD_S>0.7 of 21 and 92 days per year, respectively. In the Kroonstad profile AD_S>0.7 is 351 days in the E and 330 days per year in the G horizon. The red apedal B in the Bloemdal profile had AD_S>0.7. = 0, while the underlying unspecified material with signs of wetness had AD_S>0.7 of 203 days per year. Initial indications are that AD_S>0.7 less than 10 days per year does not lead to mottling, while AD_S>0.7 larger than 13 days per year results in mottling.

Keywords:

• diagnostic horizons
• mottling
• soil morphology
• water saturation