The optimum balance of applied nutrients is essential for ensuring higher crop yields and avoiding wasteful expenditure on fertilizers. In addition, excess use of chemical fertilizers has an adverse effect on soil ecosystem. The potato tuber yield data from a manurial trial conducted during 1993 and 1994 with twenty seven selective treatments, comprising 3 levels each of N, P and S, were utilized for developing a triangular model. The model describes in detail the threshold, economic and optimum yield barriers as well as the nutrient balance ratios for these bio-anions at respective yield barrier. The effect of N on both P and S was higher, as revealed by its distance from X-axis on the triangle indicating a synergistic effect of N on bio-anions P and S in potato crop. The model was also used in the nutrient uptake studies. It revealed a positive effect of N as well as S on N and P uptake by potato crop.
