EVALUATION OF AGRICULTURAL YIELD IN RELATION TO THE DOSES OF CHEMICAL FERTILIZERS

The present paper proposes a bifactorial model obtained by a generalization of the unifactorial Mitscherlich model. After analysing the graphic representation of the experimental data and the theoretical curves, one can conclude that they present good concordance. Treatments with nitrogen fertilizers within the limits of 0 – 200 kg a.i. ha-1 determined different optimum and maximum values for each of the four fertilization variants with phosphorus and potassium (optimum value 97 kg ha-1 N on P0K0 with yield increase of 1224 kg ha-1; optimum 107 kg ha-1 N on P50K50, with an increase of 952 kg ha-1; 111 kg ha-1 N on P100K100 with an increase of 968 kg ha-1 and 103 kg ha-1 N on P150K150 with an increase of 1413 kg ha-1). From an economical point of view, we will maximize the benefit corresponding to production value in the hypothesis that only one fertilizer is applied, namely a complex fertilizer of the type N15P15K15. For the actual price values q = 0.2 € ∙ kg−1, p = 0.6€ ∙ kg−1 the solution of the equation above is x = 221 kg ∙ ℎa−1.