The model predicted a decrease in IEs when yield targets approached Ymax. The derived borderlines are valid for current modern, high-yielding indicia cultivars with a harvest index of 0.50 kg kgˉ1 and can be used for all methods of crop establishment. Only Ymax is required as site- or season specific information when estimating nutrient requirements for a yield target making the model applicable for all irrigated lowlands in South- and Southeast Asia.