Abstract
The purpose of the research is to diagnose the mineral nutrition of potatoes based on the characteristics of the relationship between two variables. Potato yield in terms of yield increases to the control and background of mineral nutrition shows how effective doses of mineral fertilizers in double and triple combination are. The most effective option was nitrogen in a 2:1:1 combination at doses of N90P45K45 with an addition to the control of 1.47 t/ha (27.1%), and to the background of 1.28 t/ha (22.8%). In second place in terms of efficiency was the potassium variant in a 1:1:2 combination, where the increase was equal to the fertilizer-free variant of 1.45 t/ha (26.7%) and to the background of 0.98 t/ha (16.6%). Phosphorus fertilizers against the background of N45K45 gave an increase of 0.83 t/ha (14.1%), and in relation to the control – 1.29 t/ ha or 23.8%. Based on the statistical analysis of two variables "x" (fertilizer dose, kg/ha) and "Y" (yield, t/ha or c/ha), it is possible to show how much one indicator changes in relation to the other. Based on correlation and regression analysis, close relationships of two variables were obtained, which corresponded to high correlation coefficients r = 0.91 (nitrogen), r = 0.83 (phosphorus) and r = 0.93 (potassium).