Title:

Variations in soil physicochemical characteristics in some soil profiles of Okavango Delta's Pan-handle region, Botswana

Publication Year:
2013
Abstract:

The distribution of organic matter and nutrients in a soil profile provide insights in nutrient inputs, outputs, and the processes involved. A study to assess variations in physicochemical characteristics of soils was conducted at Seronga in the Okavango Delta, Botswana. Soil samples were collected at different soil depths in different land use/cover systems and analysed using standard methods. Soil organic matter (SOM), available P (AP), exchangeable Ca, Mg and K, moisture and texture significantly (p<0.05) differed with depth. Exchangeable Na, soil reaction and conductivity did not differ with soil depth. Organic matter varied from 0.19±0.01 at 0-10 cm in Terminalia sericea (Burch) ex DC to 1.00±0.6% in Dichrostachys cinerea (L.) Wight & Arn woodland at 10-20 cm. Significantly higher concentrations of AP were recorded on the soil surface in the Cynodon dactylon (L.) Pers grassland (7.13±0.07 mg/kg) and lowest (1.79±0.04 mg/kg) in T. sericea woodland. Exchangeable Ca ranged between 0.10±0.01 in T. sericea to 4.59±0.44 cmolc/kg in Ximenia americana (L.). Exchangeable Mg increased with depth, with highest concentrations (3.05±0.73 cmolc/kg) recorded at depth 30-40 cm in D. cinerea. Exchangeable K was highly concentrated on the soil surface, ranging from 0.031±0.003 in T. sericea to 0.445±0.038 cmolc/kg in fallow land. Moisture decreased while electrical conductivity and soil pH increased with depth. Sand fraction decreased with soil depth while clay increased down the profile. Soil organic matter was not correlated with clay content (R²=0.192) but significantly correlated with moisture, AP and K. The results indicate that Seronga soils are highly sandy (minimum of 96%), with low SOM, AP and exchangeable cations. Vertical variations with depth exist in the physicochemical properties of Seronga soils but there are specific to land use/cover systems. Keywords: electrical conductivity, land use/cover, pH, phosphorus, organic matter, soil depth, soil nutrient cations.

Publication Title:

Environmental Assessments in the Okavango Region

Editor:
Oldeland J, Erb C, Finckh M, Jürgens N
Series Title:
Biodiversity and Ecology
Series Number:
5
Pages:
303–310
Item Type:
Journal Article
Language:
en

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