Linear and quadratic response models with yield plateau specification were used and compared with conventional response models. The linear response plateau (LRP) and quadratic response plateau (QRP) models gave better fit to the data. The fertilizer recommendations estimated by LRP and QRP models were considerably lower than that given by conventional linear and quadratic models. Such models have been tested under field conditions and desired yield levels were obtained (with ± 10% deviation). It is suggested that the yield plateau considerations should be given a serious attention in response analysis to avoid the excess use of fertilizers than the actual need.
Linear plateau, quadratic plateau, soil test calibration
