Cost Implications and Grower Perceptions of Phosphorus Fertiliser Recommendations Based on Soil Tests Not Calibrated for Sugarcane

Input costs for sugarcane production have escalated sharply over the past five years, especially fertiliser costs. It has become imperative for growers to manage fertiliser input costs by ensuring that they have an accurate nutrition management programme in place. The South African Sugar Association Experiment Station has, over many years, contributed hugely through their research and extension departments to developing standard methods of soil analysis and critical soil norms for making cost effective fertiliser recommendations for sugarcane. The leading role that the Fertiliser Advisory Service (FAS) has played in this regard is widely acknowledged, both locally and internationally. However, in recent years growers in the north have made increasing use of laboratories where the soil tests have not been calibrated for sugarcane. This has led to diverse fertiliser recommendations and to considerable confusion among growers, as the recommendations call for excess application of phosphorus (P) and potassium (K) fertilisers in particular. This is not in the best interests of growers, nor of the fertiliser and cane processing industries. The focus of this paper is to look at the implications of using P fertiliser recommendations that are based on different soil phosphate extraction procedures than those of FAS, and that are not calibrated for sugarcane production.