The impact of sugarcane cultivation onthree Oxisols from Vanua Levu, Fiji
Keywords:Sugarcane cultivation, Oxisols, Soil properties, Fiji
AbstractThe impact of sugarcane cultivation on three Oxisols at Seaqaqa, Vanua Levu, Fiji, was studied over a period of six years (1978-1983). All three sites had been under native vegetation prior to the development of the sugarcane project. Topsoil properties including pH, organic C, cation exchange capacity (CEC), 15-bar water retention, bulk density, phosphate retention and exchangeable (Ca + Mg) were monitored ? annually during the period of the study. Most of the observed changes could be related to the decline in organic matter and associated ion exchange properties, together with increased bulk density. Subsoil samples (30-40 and 70-80cm) were analysed at the beginning and end of the study period. Virtually no changes occurred in the 70-80 cm samples at any of the sites during the six years of study. The 30-40 cm samples showed an increase in organic C and CEC at all sites, probably caused in part by ripping and rotovating during the initial land preparation. Changes at the level site were more highly correlated internally than at the two sloping sites, indicating that the effects of erosion (both adding and removing material) may have influenced some of the topsoil properties.