Some physical properties of a sandy clay loam humic soil under native forest and sugarcane in northern KwaZulu-Natal, South Africa

Abstract

The conversion of native forest land to commercial farming can have profound effects on soil physical properties. This study compared bulk density (BD), saturated hydraulic conductivity (Ks) and other physical properties of a sandy loam humic soil under native forest and sugarcane fields in northern KwaZulu-Natal. Three plots (approximately 0.1 to 0.3 ha) were demarcated at each site. Ten composite soil and core samples were collected in each plot at intervals of 0.05 m in the 0–0.2 m, 0.1 m in the 0.2–0.6 m and 0.2 m in the 0.6–1.0 m depths and analysed using standard methods. In total, 60 composite and core samples were collected from both sites. Overall, BD was higher under forest (1 410 kg m⁻³) than sugarcane (1360 kg m⁻³) while the Ks was higher under sugarcane (310 mm h⁻¹) than forest (260 mm h⁻¹). The Ks correlated positively with sand at 0–0.3 and 0–1.0 m depths. The results suggest that long term (30 years) sugarcane cultivation has the capacity to decrease BD while improving Ks of the studied soils, making the crop more beneficial on water movement characteristics especially in the drought-prone Zululand region of South Africa.

Keywords:

• bulk density
• hydraulic conductivity
• native forest
• sugarcane
• soil physical properties

Acknowledgements

The authors are grateful for (i) support provided by the National Research Foundation of South Africa (GRANT number 93593); (ii) assistance from Dr Neil Miles in selecting a suitable farm; and (iii) assistance from the farm manager of Eshowe Sugarcane Estate, in allowing us to sample fields on the estate.

Disclosure statement

The authors declare no conflict of interest.