Published in Scientific Papers. Series "Management, Economic Engineering in Agriculture and rural development", Vol. 20 ISSUE 4
Written by Florin SALA

The production variation in relation to fertilizers with N and PK was analyzed. The study was conducted on rapeseed. Four levels of fertilization with PK (0, 80, 100 and 120 kg a.s. ha-1) and three levels of fertilization with N were performed (0, 70, 140 kg a.s. ha^-1). The combination of doses resulted in 12 experimental variants, which ensured the differentiated nutrition of the plants. Production ranged from 986.88 kg ha^-1 (V1), and 3,167.33 kg ha^-1 (V9). The variation of production was described by a function of type Y = f (N, PK), in conditions of statistical certainty (R²=0.976, p<0.001). From the analysis of the values of the production increase given by N and PK, it was found that, with the increase of N doses, in the studied interval, the contribution of PK to the production increase was more and higher. Regarding PCA, PC1 explained 99.244% of variance, and PC2 explained 0.65613% of variance. The PCA diagram highlighted the distribution of the considered variants, in relation to the attributes of the experiment, N, PK and Y. The cluster analysis facilitated the grouping of variants based on Euclidean distances, in conditions of statistical safety, Coph. corr. = 0.762. Based on similarity and distance indices (SDI) the highest degree of similarity was identified between variants V2 and V12 (SDI = 11.49), followed by variants V8 and V11 (SDI = 31.71), and variants V6 and V7, respectively (SDI = 100.6).

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