Assessment of relationship between mean radius of mineral fertilizer spreading area and examined features

The paper presents results of research in the impact of selected construction parameters of the disc spreader on the mineral fertilizer spreading process. Tests were carried out in a closed room on a constructed measuring stand with the use of three mineral fertilizers (urea, nitrochalk and ammonium sulfate), the selection of which was made due to different physical properties (e.g. bulk density, coefficient of friction, size distribution) and wide application in agriculture. In order to present the impact of factors on the radius of mineral fertilizer spreading area, a four-factor experiment model was adopted, established by the method of complete randomization, in which the independent variables were: type of mineral fertilizer, level of rotational speed of the spreading disc, place of fertilizer application on the disc and angle of vanes on the disc. Results of variance analysis for the fixed model of the mean fertilizer spread radius showed that two independent variables (fertilizer type and disc rotational speed) explain the variance of dependent variable in 78.48 %. Results of variance analysis for the linear multiple regression model of the relationship between the mean fertilizer spread radius and studied features showed that 91.27 % of the variability of dependent variable is explained by the model. In the regression equation for the mean fertilizer spreading radius, independent variables include: vane angle (S), rotational speed of the disc (V), specific density of the fertilizer (G) and share of dust fractions (FP).