Economic Fertiliser Recommendations for Sugarcane

Fertiliser recommendations for sugarcane are made with a view to achieving maximum probable yields based on response data derived from decades of research by the South African Sugar Association Experiment Station (SASEX). Adaptations are made according to the experience and knowledge of consultants, but the risks of under or over fertilising are seldom quantified in monetary terms. To address this problem, a computer program called KYNO-CANE has been developed by the Agronomy Research Unit of Kynoch Ltd from the databank of SASEX fertiliser trials. KYNO-CANE accommodates a range of factors which include the influence of rainfall, soil nitrogen mineralisation potential, geographic position and the inherent soil fertility status to derive N, P and K fertiliser recommendations based on basic economic principles. The program also has the ability to evaluate the economic consequence of under or over fertilising, and aids in the correct choice of fertiliser carrier. Using current cost/price ratios (1996-97) and median representative response curves, insignificant deviations from the existing recommendations of the Fertiliser Advisory Service (FAS) of SASEX were found. However, if risk scenarios are accommodated and/or a major change in the sucrose price occurs, significant differences in recommendations may be expected.