Soil characterisation for teak (Tectona grandis) plantations in the Nzara district of Southern Sudan

[摘要] The characterization of soils in Nzara District of Southern Sudan in comparison to other tropicalteak growing countries (Tectona grandis) – in respect of extensions to existing and/or theestablishment of new teak plantations – were done by firstly considering the soils of threeexisting plantations: Yoboa, Mabarizinga and Nagondi, and secondly by considering soilsoutside and inside the existing teak plantations in respect of land uses. From these soilcharacterizations, it emerged that considerable positive returns can be expected from teakplantings in the area as an investment, provided that appropriate site management isimplemented.Climatic data of the Nzara area compared favorably with the climatic range of areas where teakgrows naturally and the world's dominant producers: mean annual rainfall 1350-1600 mm with adistribution over 6-8 months compares well with that of Myanmar (1250-3750 mm) andIndonesia (1511-2108 mm) both with at least 3 months of dry season. The mean annualtemperature of 28-350C compares well with 15-410C and 30-320C of Myanmar and Indonesiarespectively.The Yoboa and Mabarizinga sites should be prioritized as they appear slightly more suitable thanthe Nagondi site. All three sites have a dominant soil texture of Sandy Clay Loam similar toSandy 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 thehighest soil pHwater values range from 6.4±0.56 and 6.04±0.7 in top soils; 5.91±0.5 and5.46±0.61 in subsoils at Yoboa and Mabarizinga respectively; the highest soil organic mattercontent 1.8±0.34% and 1.92±0.43% in topsoil 0.89±0.16% and 1.13±0.19% in subsoils; as wellas the highest P content in both available (0.09±0.04% and 0.03±0.04% for topsoils) and totalforms (1.19±0.26% and 0.9±0.3% also on topsoils). These values though very low in absoluteterms, are not much different from those of other tropical teak-growing countries. Managementstrategies intended to preserve and improve the present status, particularly the protection of topsoil horizons against mainly water erosion, would be able to boost the site productivity.

[发布机构] Stellenbosch University