Soil characterisation for teak (Tectona grandis) plantations in the Nzara district of Southern Sudan
Thesis (MScFor (Forest and Wood Science))--Stellenbosch University, 2008.
The characterization of soils in Nzara District of Southern Sudan in comparison to other tropical teak growing countries (Tectona grandis) – in respect of extensions to existing and/or the establishment of new teak plantations – were done by firstly considering the soils of three existing plantations: Yoboa, Mabarizinga and Nagondi, and secondly by considering soils outside and inside the existing teak plantations in respect of land uses. From these soil characterizations, it emerged that considerable positive returns can be expected from teak plantings in the area as an investment, provided that appropriate site management is implemented. Climatic data of the Nzara area compared favorably with the climatic range of areas where teak grows naturally and the world’s dominant producers: mean annual rainfall 1350-1600 mm with a distribution over 6-8 months compares well with that of Myanmar (1250-3750 mm) and Indonesia (1511-2108 mm) both with at least 3 months of dry season. The mean annual temperature of 28-350C compares well with 15-410C and 30-320C of Myanmar and Indonesia respectively. The Yoboa and Mabarizinga sites should be prioritized as they appear slightly more suitable than the Nagondi site. All three sites have a dominant soil texture of Sandy Clay Loam similar to Sandy Loam of most areas of other tropical countries where teak is growing well (such as India, Indonesia and Nigeria). Yoboa and Mabarizinga however distinguish themselves by having the highest soil pHwater values range from 6.4±0.56 and 6.04±0.7 in top soils; 5.91±0.5 and 5.46±0.61 in subsoils at Yoboa and Mabarizinga respectively; the highest soil organic matter content 1.8±0.34% and 1.92±0.43% in topsoil 0.89±0.16% and 1.13±0.19% in subsoils; as well as the highest P content in both available (0.09±0.04% and 0.03±0.04% for topsoils) and total forms (1.19±0.26% and 0.9±0.3% also on topsoils). These values though very low in absolute terms, are not much different from those of other tropical teak-growing countries. Management strategies intended to preserve and improve the present status, particularly the protection of top soil horizons against mainly water erosion, would be able to boost the site productivity.